Due to human activity, artificial earthquakes occur, and their number increases every year following the strengthening of destructive human impact on the planet. My stance is suitable for the argument research essay since the question is extensive. In addition, earthquakes are becoming an increasingly severe problem every year. Therefore, it is necessary to analyze the facts and ensure that this statement is correct.
Scientists who believe earthquakes and human activity are unrelated may disagree with my stance. This is because the problem is that no accurate data indicates this fact. In addition, it is essential to divide artificial and natural earthquakes and study the impact on the latter type by humans separately. The audience can be primarily conservationists, as well as ordinary people. Both are interested in learning more about the impact of human activity on the appearance of earthquakes.
It is clear that due to intensive human activity, artificial earthquakes occur. Their number increases every year following the strengthening of man’s destructive impact on the planet (Foulger, 2018). Seismologists note that tremors are increasing in the territories surrounding large reservoirs, natural resource extraction zones, existing and developing mines and quarries, and other engineering structures.
The frequent occurrence of underground processes in the area of reservoirs is because a significant mass of water presses on the earth’s crust and erodes rocks. The difficulties are caused by the fact that it is pretty challenging to ensure that human activity can influence the movement of tectonic plates. In addition, it is crucial to determine the extent to which natural disasters appear by themselves. Earthquakes also occur as a result of volcanic activity. Due to thermal convection, updrafts arise where the plates are moving apart, spewing lava. This process is accompanied by the release of energy and generates volcanic earthquakes. Therefore, it is necessary to understand whether human activity has a direct impact on this process.
Reference
Foulger, G. (2018). Global review of human-induced earthquakes. Earth-Science Reviews, 178, 438-514. Web.
The number of earthquakes induced by rapid industrialization seems to be rising. Therefore, my objective was to research statistical data about this disaster to understand if my argument about humanity’s impact on the rise in seismic activity is valid. My approach was to find recent studies about the effect of human activity on the growing number of earthquakes. The time range for the scholarly articles was selected within the last five years. I found papers demonstrating the association between the facilitation of mining and an increase in earthquakes. The pieces that support the opposing view claim that the data about their number may be distorted due to the lack of difference in the development mechanism of natural and artificial earthquakes. Still, the authors of those manuscripts cannot deny that the termination of human activity resulted in a reduction in earthquakes. I would change my research strategy to more specific keywords, but the overall approach remains the same. Eventually, I plan to prove that the number of artificial earthquakes increases due to human activity every year, following humanity’s destructive impact.
Annotated Bibliography
Doglioni, C. (2018). A classification of induced seismicity. Geoscience Frontiers, 9(6), 1903-1909.
This paper aimed to classify anthropogenically caused tectonic destruction into four groups: fluid injection, fluid removal, high-pressure injection, and crustal loading and unloading. The author’s main argument is that there is no sufficient data about the correlation between human activity and increased earthquakes. Still, they accept that the mechanism of damage from mining equipment is undeniable. This article’s data appears reliable because it was published within the last five years in a peer-reviewed journal rated as the eighth-best journal in this field. The classification and detailed description of mechanisms support the argument that changes in the natural “tectonic settings” can trigger seismic activity (p. 1908). Indeed, this paper is closely related to the study by Kang et al. (2019) explaining manufactured damage to the lithosphere. The authors conclude their article with the suggestion of implementing mathematical modeling to prevent earthquakes from industrial activity.
Foulger, G. R., Wilson, M. P., Gluyas, J. G., Julian, B. R., & Davies, R. J. (2018). Global review of human-induced earthquakes. Earth-Science Reviews, 178, 438-514.
Despite accepting that anthropogenic activity can induce seismic activity, the authors of this paper claim that the number of artificial earthquakes is overestimated on the HiQuake database. This manuscript was an invited review in a peer-reviewed journal with a high impact factor. Although the authors question the validity of information on this database, they admit that even if the magnitude of these events was primarily low, they were caused by human activity. Therefore, this article proves that the number of earthquakes increased due to the rapid development of mining. Still, it states that their magnitude is often low, causing no harm to the population.
Kang, J. Q., Zhu, J. B., & Zhao, J. (2019). A review of mechanisms of induced earthquakes: From a view of rock mechanics. Geomechanics and Geophysics for Geo-Energy and Geo-Resources, 5(2), 171-196.
This article discusses three leading human activity-related causes of artificial earthquakes: increased pore pressure during water injection, stress change due to temperature change and fluid extraction, and altered coefficient of friction. This paper is credible because it was published recently in a peer-reviewed journal. The authors give examples of large earthquakes triggered by industrial activity in Germany in 1989 and the USA in 2011 (p. 172). Moreover, the authors claim that minor induced earthquakes occur frequently, but it is difficult to track them; thus, the data may be misleading. Still, this paper supports my argument by describing how the equipment used in industry results in shear and tensile damage to rocks. Furthermore, this article helps show how mining methods of fluid injection and extraction exert thermal stress and corrosion, causing crack progression, which increases the likelihood of seismic events.
Van der Baan, M., & Calixto, F. J. (2017). Human‐induced seismicity and large‐scale hydrocarbon production in the USA and Canada. Geochemistry, Geophysics, Geosystems, 18(7), 2467-2485.
This source compares seismic activity in six U.S. states and three Canadian provinces, showing that increased oil mining activity using horizontal drilling and hydraulic fracturing caused increased earthquakes. This paper analyzes induced earthquakes from 1965 to 2014, providing a relatively objective assessment of fifty-year data from credible databases of the two countries (p. 2469). The article was published within the last five years in a peer-reviewed journal about planetary processes by the members of the American Geophysical Union. Overall, it helps support my argument about the continuous increase of artificial earthquakes because of the destructive effect of human activity.
Vlek, C. (2019). Rise and reduction of induced earthquakes in the Groningen gas field, 1991–2018: Statistical trends, social impacts, and policy change. Environmental Earth Sciences, 78(3), 1-14.
This manuscript explores artificial earthquakes related to oil and gas mining in the Netherlands from 1991 to 2018, showing a steady increase in the magnitude of induced seismic activity. This work was published in a peer-reviewed journal recently; thus, it can be considered reliable. According to this paper, the main reason for the growing seismic magnitude is “increasing reservoir compaction” (p. 2). Overall, the article contains valuable statistical data about the increasing number and strength of earthquakes in this region.
Wang, R., Gu, Y. J., Schultz, R., & Chen, Y. (2018). Faults and non‐double‐couple components for induced earthquakes. Geophysical Research Letters, 45(17), 8966-8975.
This manuscript states that the statistical information about the number of induced earthquakes is inaccurate because the mechanism of appearance between natural and artificial seismic activity was found to be identical. It can be considered a credible paper because it was published in a high-impact peer-review journal within the last five years. Although the authors’ point seems valid, it still cannot disprove my argument because, as the article states, various theoretical reports and experimental studies explained the direct correlation between hydraulic fracturing and increased seismicity.
Geology refers to the study of the processes that lead to the formation of rocks and the processes that contribute to the shape of the earth. Rocks can be classified into three categorize: “metamorphic, sedimentary, and igneous’’. Geology has played a significant role in reshaping the terrain of Washington State thus making it what it is today (Babcock and Carson 15). Even though much of the landscape is today covered by vegetation, this was not the case before geological activities were put in place to save Washington State from environmental degradation. The geology of Washington State owes its origin to several natural disasters (Babcock and Carson 24). This paper will examine the effects of the Nisqually earthquake on the people of Washington State.
Discussion
Meaning of a Geological Disaster
A geological disaster refers to natural environmental accidents which may have far-reaching effects on human beings and properties. Some of the geological disasters include sinkholes, landslides, volcanoes, tsunamis, and earthquakes. Washington State is one of the places in the world that has experienced natural catastrophes. “An earthquake can be defined as the shaking of the surface of the Earth” (Carson 37). This process can be triggered by volcanic activities and explosives.
Movements that take place along faults are popularly known for causing earthquakes. Earthquakes can also lead to the occurrence of other catastrophes like tsunamis and landslides (Carson 22). The occurrence of earthquakes is widespread across the world and some countries like Japan and China are more prone to earthquakes as compared to other countries which rarely experience cases of earthquakes. There is always no specific way of detecting and avoiding impending earthquakes. However, various initiatives can be taken to reduce the impact of earthquakes on people (Carson 55). For example, developed countries like USA and Japan have designed buildings in such a way that they can resist the shocks caused by earth tremors.
The Richter scale is used for quantifying and recording the degree of an earthquake. Intensity quantifies the seriousness of an earthquake depending on how much it affects human beings (Williams 65). Minor earthquakes cannot lead to serious damages that can be identified. However, the impact of major earthquakes can be felt over a large geographical area. For example, the recent Haiti earthquake had serious effects that attracted international attention.
Nisqually Earthquake in Washington State
In the USA, many cases of earthquakes are common in California and parts of Alaska. Washington State and Nevada have also experienced earthquakes. Alaska has however had a majority of the earthquake cases in the USA (Carson 39). The Nisqually earthquake went into records as one of the greatest earthquakes that have ever occurred in Washington State. It took place on the twenty-eighth of February in the year 2001 at 10:54 am (Malone 78). The duration for which the earthquake lasted was forty seconds and it was recorded at 6.8 on the Richter scale. The impact of the earthquake was felt several miles away from Washington State.
Effects of Nisqually Earthquake in Washington State
The earthquake had many effects which can be discussed as follows. A lot of private property was ravaged by the earthquake (Walter 24). The people interviewed on the impacts of the earthquake revealed that they lost a lot of valuable properties (Malone 88). For example, one of the interviewees said that his house sustained serious damages that could cost him a lot of money to repair and this forced him to relocate to another apartment (Joseph 3). Another person that was interviewed said that his business premise was seriously affected by the tremors and they were moved to other buildings. In the process of moving, he lost his customers hence his business was adversely affected.
Although only one person was reported to have died of a heart attack triggered by shocks from the tremors, many people were seriously injured. The Alaskan highway was also seriously damaged and this caused serious traffic snarl-ups (Malone 94). The earthquake also led to long durations of power black-outs that paralyzed business activities in Washington State and this caused losses in businesses.
Apart from these effects key buildings, bridges along major highways, and schools were closed for some time to give room for inspection. In this process learning activities and services could not be accessed. This caused a lot of inconvenience to the residents of Washington State (Malone 96). Cases of water shortages were also reported in some parts of Washington State because water installations were disrupted by the tremors which led to the rapture of the pipes.
Conclusion
Even though earthquakes may cause serious damages, the effects can be reduced if people are informed about safety measures and how to handle themselves during such disasters. For example, people living in areas prone to earthquakes should be very alert and ready to face such cases. If an earthquake occurs while you are inside a house, you should not panic. You should also try to avoid staying close to windows and also check on objects which may be falling down (Romaine 3). If it finds you outside a building or under a tree, it is advisable to move away to an open place free from any object that may drop down and injure you (O’Dowd 13). Immediately after the earthquake, you should check if somebody has been injured and carry out first aid. You should then carry out an inspection to determine if the gas, water, and electricity connections are not interfered with.
References
Babcock, Scott and Bob Carson. Hiking Washington’s geology. New York: The Mountaineers, 2000. Print.
Carson, Bob. “General geology of Southeastern Washington.” Whitman Geology 12(2000): 13-15.
Joseph, Davidson. “Nisqaully earthquake.” Interviews with Anne Mary. By Dale Salk. New York: Wiley and Sons, 2010. Print.
Malone, Stephen. “Identifying the rupture plane of the 2001 Nisqually, Washinton, earthquake.” Bulletin of Seismological Society of America 23(2008): 36-39.
O’Dowd, Mary. “Nisqually earthquake.” Interviews with Anne Mary. By Dale Salk. New York: Wiley and Sons, 2010. Print.
Romaine, Garret. Gem trail of Washington. New York: Gem Guides Books, 2004. Print.
Walter, James. “Nisqually earthquake.” Interviews with Anne Mary. By Dale Salk. New York: Wiley and Sons, 2010. Print.
Williams, Hill. The restless Northwest. Washington D.C.: Wahington State University, 2002. Print.
In many emergencies plans public health and government agencies launched, thorough organizational planning ends when death is confirmed, and the remains are “sent to the mortuary.” There is often a lack of understanding that identifying individual bodies and even bodily fragments (in the aftermath of many significant disasters) is the first and perhaps most crucial step in starting and supporting the grieving process that allows families and the entire community to respond to these incidents in a manageable manner. Thus, it is worth noting that Disaster Victim Identification is the name given to this procedure.
Details
Given that many multi-fatality occurrences include victims from all over the world, it is unavoidable that the investigators entrusted with identifying these victims would have been trained, accumulated expertise, and worked under the jurisdictional supervision of a variety of nations. This can be perplexing, especially when these investigatory teams are entrusted with cooperating (De Boer et al., 2019). As a result, some standardization in the identification procedure is necessary, especially when multi-jurisdictional victims and investigators are involved.
It should be noted that the suggestions in this Decision Notice are backed up by an Outline Business Case, which contains preliminary evaluations and material that will be expanded upon as the implementation phase progresses. Section22a must be developed to determine and agree on crucial components of the partnership, such as the presence and continuous support of the RICC and the design, development, and funding of the planned Regional DVI Coordinator post. This agreement should also recognize the command-and-control mechanisms because the suggested employment model is a virtual hub and spoke architecture (Williams & Wienroth, 2014). Options for joint training delivery, post-incident debriefing and assistance, and recognition of health and safety factors beyond PPE should all be part of the implementation process (Johnson & Riemen, 2019). The idea to consolidate training and accreditation data into a single central system should be carefully considered since it will result in a two-tier structure within forces in skill management rather than the intended one point of truth (Ellis, 2019). Moreover, the proposed Principle 2 necessitates specific awareness of and adherence to the regulations and legislation that govern the extent of a practitioner’s investigative abilities.
This does not imply that the practitioner must comprehend the legal landscape of the crime they are investigating (though in most circumstances it will be advantageous to their investigation), but it does imply that they must understand the legal powers that govern their conduct. It is their express responsibility to ensure that they always work within these limitations since any activity that strays outside of these bounds exposes practitioners to malpractice liability (Williams & Wienroth, 2014). This concept stops a practitioner from wandering into areas of problematic practice and then claiming ignorance of the consequences of their acts (Watherston et al., 2018). This requirement is becoming increasingly important as more investigations focus on non-local storage, where governance at the point of existence may not be adequately defined or understood.
Conclusion
One of the essential trade-offs in primary development is the quality assurance vs. practical enforcement trade-off, which requires striking a delicate balance between the two. Given their broad scope, the present ACPO rules may appear to offer nothing in terms of defining and guaranteeing acceptable forensic behavior in practice (Brookes & Thompson, 2019). As a result, it is unclear whether practitioners are merely paying respect to these principles and maybe not embracing their spirit of quality assurance, although often declaring adherence to them (and presumably keeping within their limitations given how widely they can be construed). This is in no way the fault of the practitioner or the principal creators; given their present scope of application, it is probable that all activity, save negligent actions, would have complied with ACPO. To have any weight in their application, principles must define and restrict the borders of acceptable behavior, which is an issue that the existing principles may have.
Primary sources are the ones providing first-hand evidence on the events or phenomena that one is studying. Such sources include diaries, photographs, video and audio recordings, interview transcripts, works of art, statistical data, and others. All of these types of sources give the researcher a possibility to learn about the investigated matter directly by observing it or reading/listening about it from first-hand witnesses. In case of the Chernobyl Nuclear Plant Disaster, the most relevant primary sources include reports, documents, and local newspapers of that time, photographs, and interviews of witnesses. By using such resources, one can obtain the possibility to learn unbiased facts and obtain the most relevant information about the event or phenomenon under investigation. Moreover, when analyzing primary sources, the researcher can become immersed in the atmosphere in which the object of investigation existed and the circumstances under which it developed. For instance, for historians and archeologists, such primary sources as ancient fossils or some tribes’ belongings serve both as sources of information and inspiration. On the other hand, for someone analyzing a political or environmental issue, reports and pertinent news releases will be helpful sources of reliable data.
Meanwhile, secondary sources offer second-hand information and analyses from other researchers. Secondary sources include books, reviews, and scholarly articles investigating the subject of research. By analyzing secondary sources, one can get a deeper understanding of both the analyzed phenomenon and the primary sources. While primary sources offer a first-hand view of the situation, secondary ones enable the researcher to synthesize the material on the topic.
Explain why it is important to consult a variety of sources when conducting historical research
Both types of sources are crucial in research since they complement each other. Whereas primary sources offer credible evidence, secondary sources provide additional information and valuable synthesis. However, even when one possesses a primary and a secondary source, it is not enough for completing a thorough research endeavor. One needs much more than a few sources, however credible they might be. It is of utmost importance to consult a variety of sources when conducting historical research since in each new source, valuable additional evidence can be found. Also, when the same data occurs in several sources, its credibility increases. At the same time, the presence of different pieces of information gives the researcher food for thought and allows posing new questions and seeking new answers. That is why the more sources one has at one’s disposal, the better. It is crucial to consult not only a wide range of sources but also different types of them since authors of articles and books, for instance, have divergent approaches to synthesizing data.
Suppose there was a hypothetical earthquake off of the coast of New York. You are commissioned by the mayor of New York to draft a report describing exactly how this had occurred. What would your report say? Include in your answer the various aspects of plate tectonics and plate movement.
New York is situated on the Atlantic coast that is characterized as a tectonically calm and passive margin. However, even despite the absence of seismic activity, the city has many faults (Toor). Therefore, the following faults would be included in the report as potential causes of the earthquake:
the 125th Street fault is the largest of all. It extends from New Jersey to the East River, runs along the street. One part of the fault runs into Roosevelt island whereas another part extends to the northern end of Central Park;
the East River fault looks like “an obtuse angle,” and its top portion runs parallel to the west of Central Park. The fault then takes a horizontal turn near 32nd Street, extends into the East River, and stops near Brooklyn (Toor);
the Dyckman Street fault is situated in Inwood. The fault crosses the Harlem River and moves into Morris Heights;
the Mosholu Parkway fault is located to the north of the 125th Street and Dyckman Street faults;
the Dobbs Ferry fault is located just outside the city in suburban Westchester;
the Ramapo fault extends from eastern Pennsylvania to the mid-Hudson Valley (Toor).
The investigation of the mentioned faults may help to identify the origin of the earthquake and predict the possibility of another one. Another part of the report to the mayor would concern the analysis of plate movement and plate tectonics. As is known, earthquakes occur when there is a movement of tectonic plates. New York is situated in a non-seismic zone, so an earthquake in this city would urge the thorough search for changes in tectonic boundaries in the area. Plate tectonics may serve as an effective predictive theory (Garrison and Ellis 97). Thus, it would be necessary to include in the report the data available on plates on which New York and the nearby regions are located. This information would help to make conclusions about the causes of the earthquake.
The plates float on a deformable asthenosphere and can move freely in relation to each other (Garrison and Ellis 77). The interaction between plates can occur along their boundaries. Sometimes, plates slide along one another. Then, they overlap, and a gap occurs. Plates’ movement can be divergent, convergent, or transformational (Garrison and Ellis 77). In the case of divergent boundaries, two plates move apart. In convergent movement, the plates move toward one another and merge. Transform, or transverse, boundaries occur when two plates slide past each other (Garrison and Ellis 77).
The study of earthquakes allows understanding layering better (Garrison and Ellis 63). The forces causing earthquakes appear due to seismic waves. Some of these waves can diffuse through the Earth, bending or reflecting on their way (Garrison and Ellis 63). Finally, the waves may reappear at the Earth’s surface. The thorough analysis of the location and time of the waves’ occurrence allowed scientists to study the planet’s interior. Seismic waves are divided into two types: body and surface. Surface waves move along the surface of the Earth. They ripple the free external part of the area and can be seen “as an undulating wavelike motion” in the ground (Garrison and Ellis 63). Body waves do not produce such a dramatic effect, but their analysis helps to investigate the interior structure of the Earth.
Works Cited
Garrison, Tom, and Robert Ellis. Oceanography: An Invitation to Marine Science. 9th ed., CENGAGE Learning, 2016.
The latest Japanese earth quake is the Tōhuku earthquake which occurred in March 2011. It is also referred to as the Great East Japanese Earthquake. The earthquake had a magnitude of 9.0 on Ritcher scale occurring at 14:46 Japan Standard Time (JST) on Eleventh of March, 2011.
The earthquakes epicenter was approximately seventy two Kilometers on the Eastern part of Oshika Peninsula and a Hypocenter of approximately thirty two kilometers beneath the waters. The government of Japan confirmed this as one of the catastrophes of its kind (Ito).
The earthquake took place at a zone of subduction between the pacific plate and the plate that lies below the Northern Honshu. The rate at which the pacific plate undergoes displacement is at eight to nine centimeter per annum, hence the plate subduction of the plate led to a discharge of large amounts of energy leading to a geological event. This interaction between the two plates resulted to stress initiating seismological events.
One of the effects of the seismological event led to a rise in the sea level (Chang 5). Since the region of subduction of the two plates does not lie on a straight line, the faulting resulted to a large earthquake with a magnitude of more than 8.5.The JMA (Japanese Meteorological Agency) indicated that the catastrophe broke the fault region extending from Iwate to Ibaraki having covered 500km by 200km.
The Tōhuku earthquake was purported to have comprised of three sequences of events leading to extensive destruction to infrastructure. The catastrophe initiated extremely destructives waves of the tsunami of up to thirty seven point nine meters/ one hundred and twenty four feet that attacked Japan in just minutes following the earthquake.
In some of the places the waves travelled as far as 6mi (ten kilometers) inland with short waves being felt in most of the adjacent countries after a few hours of the earthquake. The Japanese government issued warnings prior to the catastrophe ordering relocations along Pacific Coast. Prior to the earthquake, warnings were issued out to 20 nations close to Japan as well as countries close to United States Pacific Coast (Wire Staff).
The effects of this catastrophe was very pronounced such that the Japanese NPA (National Police Agency) thereafter confirmed 12,228 missing persons, the death toll was at 14,238 persons whereas the injured cases were 5,314 in all the Japanese prefectures. There were 125,000 buildings which were also destroyed during the earthquake.
The disaster affected most of the infrastructure such as railway network as well as the roads cutting off communication within the affected region. Great destruction was also felt in the Northeastern Japan where approximately 4.4 million dwellings were cut off from electricity supply including 1.5 million households which were completely cut off from safe water.
Countless electrical power plants were destroyed and more than 3 nuclear reactors were destroyed as a result of hydrogen gas build up inside the nuclear reactors covering due to the failure of the cooling system. Most of the people living within a radius of twenty kilometers within t nuclear plants were ordered to relocate to safer regions. Furthermore, the United States recommended that all of the U.S citizens be relocated up to eighty kilometers of the nuclear plants.
The magnitude of the Tōhuku earth quake makes it the greatest and most powerful geologic catastrophe to have affected Japan. It is one of the top five most harmful catastrophes ever since the current documentation of catastrophes started in 1900. The prime Minister to Japan stated this as the most destructive and harmful geological event to have hit Japan since the second world war causing a heartfelt crisis to this country.
As a result of the earthquake, Honsu was moved 7.9ft(2.4m) east and the earth was shifted from its axis by approximately 3.9in(10cm) (Chang 6). Economically the quake cost Japan a big loss. Japan was forced to compensate the banking sector a total of 15 trillion Japanese Yen with the aim of returning the market systems in normal working condition.
According to the estimates by the World Bank, the total damage caused by the earthquake is estimated at 122 to 235 billion U.S dollars. The government of Japan on the other hand estimates the cost of the Catastrophe that caused a lot of strive in Northeast at 309 billion dollars and this makes this the world’s most costly catastrophe.
After the Tōhuku earthquake, Japan continued experiencing several after shocks. More than nine hundred aftershocks have been experienced in Japan with nearly sixty of them having a magnitude of 6.0M and up to three aftershocks having more than 7.0M quake occurring in March and the third aftershock occurring on April 7,2011 even though its magnitude was under contention.
The epicenter of this aftershock was submarine, sixty six kilometers off Sendai coast. Never the less, the JMA estimated the magnitude of this aftershock as 7.4, whilst United States geological survey brought it down to 7.1 (Wire Staff). During the aftershock, there were four lives lost, and power was disconnected across most of the Northern part of Japan as a result of destruction of the electrical cables and other infrastructure including the external power disconnection to Rokkasho Reprocessing station and Higashidori Nuclear station.
In addition, the earthquake resulted to a large Tsunami which led to the destruction of Japans islands which lie along the pacific coastline resulting to thousands of deaths and strive in the whole town. Most of the countries bordering Japan were affected by this tsunami. For instance, Chile was affected by a wave length of 2m high in spite of its being the furthest country, 17,000 kilometers away from Japan.
In conclusion, Tōhuku earthquake is one of the five major catastrophes and the latest earthquake to have occurred in the world since the beginning of catastrophe documentation. The data collected from this earthquake is important to both the geologists and seismologist since it provides valuable information across several disciplines for instance on how structures should be constructed to withstand extensive periods of shaking in the event of any seismological event.
Works Cited
Chang, Kenneth. “Quake Moves Japan Closer to U.S and Alters Earth’s Spin.” New York Times, 14 Mar. 2011. Print.
Ito, Masami. “Kan Names Quake at Pep Talk.” 02 04 2011. The Japan Times Online. Web.
Wire Staff. “Tsunami Warnings Issued for atleast 20 Countries after Quake.” CNN, 11 Mar. 2011.
This paper explores both 2008 and 2013 Sichuan earthquakes in China. It provides detailed descriptions of how each earthquake occurred, similarities and differences between the two incidences. In addition, it shows social and economic effects of the two earthquakes on people.
The Sichuan Earthquake in 2008
On May 12, 2008, a devastating earthquake with a magnitude of 7.9 or 8 on the Ritcher scale rocked Sichuan Province of China. The aftermaths were catastrophic and immediate. It killed around “90,000 people and injured nearly 363,000, destroyed more than 15 million homes, left 10 million homeless and 1.5 million displaced, and it caused more than $20 billion in damage” (Hays, 2011, p. 1).
This was the worst and the most devastating earthquake since “the Tangshan earthquake of 1976 in China” (Hays, 2011, p. 1). The 2008 Sichuan earthquake was stronger than the earthquake that hit Kobe, Japan in 1995. Sichuan took approximately 80 seconds. It caused a movement in the ground of about seven meters close to the epicenter.
The quake broke huge mountains and made rivers to alter their course. In addition, it destroyed bridges, buildings, and pavements. The quake erased the entire town and ripped off highways. It cut off all means of communication in the affected areas. Landslides from the quake buried homes as the wave caused thousands of buildings to collapse and topple.
Geological accounts of the 2008 Sichuan Earthquake
Geologists have long established that there is the Longmenshan fault in Sichuan. It ranges between 250 and 300 kilometers with a width of 30 kilometers. They estimated that the quake could have caused a large movement (13 meters) from the fault line. This is a significant movement. The shaking was massive for more than two minutes. Evidence from the bedrock indicated that damages started from the epicenter and progressed in the northeastern direction.
Scientists noted that the catastrophic strength and magnitude could have emanated from the impacts of the two colliding tectonic plates (Hough, 2002, p. 34). The Longmenshan swerved in two places, which had a length of 100 kilometers and a width of 30 kilometer. In addition, other parts sheered for about 150 kilometers in length and 30 kilometers in width.
Sichuan has three major fault lines in which Longmenshan is the next one to Chengdu (Scholz, 1991, p. 12). Chengdu is a city near to the epicenter of the quake. However, Chengdu did not suffer severe damages because it lies “on a stable area basin of Sichuan and massif of Yangtze” (Hays, 2011, p. 1). There were no reported cases of fatalities from Chengdu.
Some scientists noted that a huge dam constructed along the fault line could have played a major role in initiating the earthquake. They noted that the water reservoir could have built the pressure, which caused the quake. Zipingpu Dam’s height is 156 meters. The dam is 550 meters away from the areas of weaknesses and merely 5.5 kilometers far from the epicenter.
Scientists estimated that the weight of the water at the reservoir could have been 315 million tons. This weight was enough to trigger an earthquake or increase its magnitude. Others claimed that Zipingpu dam could have played a role in altering the time or magnitude of the earthquake. Hence, the result was more violent than expected because the dam was close to the fault line.
Most scientists have agreed that such huge dams, which are close to fault lines, can result in tremors. However, other scientists have dismissed the claims that the quake could have originated from the dam. They note that the area of Sichuan lies on an active fault lines. Moreover, the shock was too intensive to result from the dam. Hence, Zipingpu dam was not a major cause of the quake.
Damages of the 2008 Sichuan Earthquake
The earthquake cut off all means of communication. It caused underground infrastructure to rupture and collapse. It claimed thousands of human lives and animals. Moreover, several people sustained serious injuries. Socially, the Sichuan earthquake of 2008 destroyed families and relations.
The direct economic cost from “the earthquake was over $146 billion” (Hays, 2011, p. 1). Sichuan Province incurred more than 91 percent in losses. The estimated value of the lost property during the earthquake was $122.7 billion. After the earthquake, many people became poor because of the lost property.
Although authorities knew that Sichuan was on active fault lines and susceptible to earthquakes, there was no mitigating approaches to subsequent damages or evacuation and rescue strategies in place to respond to the potential earthquake.
Some claimed that there were clear indications from strange behaviors of animals before the quake. For instance, frogs and toads started to migrate in large numbers before the earthquake took place. These were predictors of the impending quake in the region.
The Sichuan Earthquake 2013
The Sichuan earthquake of April 20, 2013 had a magnitude of 6.6 (EQECAT Inc., 2013, p. 1). The quake generated strong waves of up to 50 kilometers away from the epicenter. However, the impact of the quake was strong in the affected area. Shaking continued for about 60 seconds.
Initial reports had indicated that the quake had claimed about “200 fatalities with thousands of injured persons while others were missing” (EQECAT Inc., 2013, p. 1). The number of fatalities could have risen because of the dense population within the region and impacts of the shaking ground.
Immediate areas near the epicenter of the earthquake suffered severe damages. In most cases, damages are severe in Sichuan province because of a high population density. This earthquake mainly affected rural locations of the province. Many farmers lost their crops and livestock mainly around the Tibetan Plateau.
Damages of the 2013 Sichuan Earthquake
Like in the previous earthquake, the region near the epicenter suffered the most damages. Generally, any structures or lives in these areas become extremely vulnerable when shaking takes place. This was also the experience in the 2008 earthquake. While there are some reinforced buildings, many people reside in buildings or structures, which lack reinforcement against earthquakes.
The earthquake left more than 100,000 people without homes and any means of communication. Sichuan is an agricultural zone in China while Chengdu has thrived on manufacturing. As a result, Sichuan has been important to both local and foreign investors. Most commercial centers are near large rivers. These areas have weak grounds, which are prone to movement during shaking.
Thus, the damage to industrial plants and agricultural land were severe. However, the 2013 earthquake did not affect most commercial buildings and industrial plants. Damages from the 2013 earthquake were not widespread relative to the 2008 earthquake.
After the experience of the 2008 earthquake, the Chinese government took some initiatives to “protect its citizens by investing in schools and hospitals” (EQECAT Inc., 2013). It confirmed that no school collapsed in the 2013 Sichuan earthquake. However, there were widespread landslides, which hampered aid efforts and emergency rescue.
Geological explanations
Scientists noted that the quake could have occurred along the fault line on the Longmenshan, which was 12 kilometers in depth. The M7.9 earthquake of 2008 originated from the same fault line of Longmenshan. The tectonics of the Himalaya region and Eurasia plates are responsible for seismically active tectonic plates in the region. These plates converge to create seismically active places (Grotzinger and Jordan, 2010, p. 184).
Conclusion
In both earthquakes of 2008 and 2013, areas near the epicenter experienced the most devastating damages to both lives and properties. Generally, the Longmenshan fault line has been the main source of both the 2008 Sichuan earthquake and the 2013 Sichuan earthquake. The magnitudes of these quakes were different. In addition, impacts differ based on the number of fatalities and damages to property.
Thus, economic and social impacts of both earthquakes are similar, but differ based on the intensity of each quake. On this note, the 2008 Sichuan quake caused the greatest damage than the subsequent one of 2013. In the 2008 earthquake, there were speculations that that the quake could have originated from the large dam next to the epicenter.
However, some scientists warned that the impact was so severe and devastating than what could have originated from the dam. Overall, they concurred that dams do have a role in influencing the time or magnitude of earthquakes. The two colliding tectonic plates have been responsible for the two earthquakes in Sichuan. They release the built up seismic strain that causes damages on the surface of the earth.
References
EQECAT Inc. (2013). M6.6 Quake in China Responsible for 200+ Fatalities. Web.
Grotzinger, J., and Jordan, T. (2010). Understanding Earth (6th ed.). Cranbury, NJ : WH Freeman.
Hays, J. (2011). SICHUAN EARTHQUAKE IN 2008. Web.
Hough, S. (2002). Earthshaking Science: What We Know (and Don’t Know) about Earthquakes. New Jersey: Princeton University Press.
Scholz, C. (1991). The Mechanics of Earthquakes and Faulting. Cambridge: Cambridge University Press.
Mississippi River, the longest river in the United States and, with its extensive offshoots, is one of the most important river systems of the world. Times of yore Ojibwa Indians, roaming the forests of Wisconsin, called it Missi Sipi, or “Great River.” In the lower valley, where the impulsive current distended in flood time runs over its banks to change millions of acres of productive land into a moving sea, other tribes labeled it the “Father of Waters.” Both names were appropriate, for the scope and volume of this vast stream have made it almost a synonym for great rivers everywhere; even the Volga River has been termed the “Russian Mississippi.”(Lane, 1)
The length of the Mississippi has been variously interpreted. The U.S. Geological Survey calculates its length at 3,710 miles (5,970 km) from the headwaters of Missouri to the delta outlet on the Gulf of Mexico. The Nile River is slightly longer. The length of the Mississippi is not constant; horseshoe loops are cut through, reducing the figure, which swells again when new loops are created as the river meanders down its lower valley..”(Lane, 1)
Meanwhile the American Civil War was going on (from 1861 to 1865), the Mississippi provided a route for invasion for the Union militaries. The taking into custody of river cities like New Orleans, Memphis, and Vicksburg, Mississippi, split the Confederacy in half and made the triumph for the North a reality. In the post-war time, railroads in a little while replaced most of the waterway’s previous traffic of steamboat. As the Eads Bridge in reached its completion in 1874, it linked St. Louis and East St. Louis, Illinois; this supplied a most important rail passage stretching over the river. A number of overpasses were constructed in the years to follow. (Coffman, 1)
The significance of the Mississippi as a shipping route has augmented very much since the 1920s. No other way of carriage can transport heaps of weighty, massive freight as inexpensively as the tugboats and barges on the grand river belt. (Coffman, 1)
The river has been the object of legend, song, and story. For thousands it became the passageway to dreams of greater fortune or a better way of life. For others it was the commercial lifeline for the central section of the United States. But, as was shown again in the summer of 1993, the Mississippi River is also a powerful, unpredictable, and deadly force.
Formed from melting glaciers of an ice age two million years ago, the Mississippi and its tributaries drain 31 states and two Canadian provinces, a total of 3.2 million square kilometers (1.2 million sq mi). This river basin provides some of the richest agricultural lands in the world, but farming these fertile floodplains (the areas underwater during a major flood) is sometimes difficult. (Mississippi Flood, 1)
Every year the Mississippi spills over its banks in a natural cycle. It deposits alluvium–particles of sand and clay–over miles of floodplain. This alluvium enriches the soil and supports an intricate web of plants and animals. It also provides rich farmland. But to live and farm in the floodplain, people have had to learn to control the power of the Mississippi. (Mississippi Flood, 1)
Floods: An Overview
Floods take place when the waters of rivers, lakes, or streams spill over their banks and pour out onto the adjoining land. Time and again bodies of water rise greatly in volume without causing floods. From time to time mainly in the spring, the amount of water in rivers and streams rises to a higher level than usual, and the excess spills over the banks, causing little damage. It is only when great amounts of overflowing water cause severe damage to large surrounding areas that bodies of water can be said to be in flood.(Smith, 1)
Floods are caused by many different things. Often heavy rainstorms that last for a brief time can cause a flood. But not all heavy storms are followed by flooding. If the surrounding land is flat and can absorb the water, no flooding will occur. If, however, the land is hard and rocky, heavy rains cannot be absorbed. Where the banks are low, a river may overflow and flood adjacent lowlands. (Smith, 1)
Sometimes less severe storms can cause flooding. This happens when earlier rains have filled the soil with so much moisture that no more rain can be absorbed. If the ground is frozen, the rains are unable to sink into the hard earth. The waters then swell the rivers, and the result is damaging floods. (Smith, 1)
In numerous parts of the world, floods are caused by tropical storms called hurricanes or typhoons. The hurricanes of the West Indies and the Caribbean start in the Atlantic Ocean north of the equator. As they gather force, they move west and may curve north toward the Gulf Coast of America or the Atlantic seaboard. They bring destructive winds of high speed, torrents of rain, and flooding. Along the coast, flooding is sometimes caused by storm winds and high tides.
Inside such places as the northern United States, Canada, and Scandinavia, where winter temperatures are low, heavy snowfalls may cause floods. Sometimes very deep snow stays on the ground until the spring thaw sets in. When warm weather comes, the snow melts quickly and the danger of flooding increases. If the ground is not frozen when the snow falls, quantities of melting snow can sink into the earth, and no flooding will occur. But if the ground is frozen far below the surface, very little of the melting snow is absorbed by the soil. This is especially true in mountainous areas when melting is accompanied by spring rains. Water washes down the steep slopes of the mountains. Mountain streams and rivers overflow, bringing floods and destruction to the valleys below. (Smith, 1)
The Great Flood
Sizeable downpour in June and July in the Upper Midwest, shared with damp soil situations, was the reason for ruthless overflow in the Upper Mississippi River basin. During June, 8 inches of rainfall fell transversely to the Upper Midwest. This caused overflow on waterways in Minnesota and Wisconsin and ultimately pressed the Mississippi River to a top at St. Louis on July 12th of approximately 43 feet, equating the preceding phase of evidence. (The Great USA Flood of 1993, n. p)
During July, Iowa was struck with frequent highest downpours. Outburst overall equal to 8 inches was another time familiar. Heavy downpours were recorded at Des Moines, Iowa and Skunk rivers specifically the cities of Iowa and Des Moines were severely struck on July 9 by the flood.
The gushes from these rivers collective with previously near-record streams on the Mississippi River to thrust the juncture at St. Louis equipped a latest confirmation elevated stage of 47 feet. (The Great USA Flood of 1993, n. p)
By almost the end of July heavy downpours started again in Missouri, Kansas, North and South Dakota and Nebraska. In these areas record overflow and flooding took place. The Missouri River ridged at around 48.9 feet at Kansas City shattering the earlier flood records, established in 1951, which was 2.7 feet. This ridge drove on through the Missouri River making latest records at St. Charles, Boonville, Hermann and Jefferson City. This record pours linked the by now over spilling Mississippi River very soon north of St. Louis, and rammed the Mississippi to one more record peak at St. Louise which was 49.47 feet. (The Great USA Flood of 1993, n. p)
Restraining the river has never been relaxed. More than a hundred years ago, author and river pilot Mark Twain noted that people “cannot tame that lawless stream, cannot curb it or confine it.” The writer’s words proved true in 1993 when an unusual weather pattern brought two months of heavy rain to the upper Mississippi Valley. This water, combined with waters from heavy spring rains throughout the Midwest, resulted in the worst flood of the upper Mississippi in the 20th century. (Mississippi Flood, 1)
The flood of 1993 caused extensive damage. Water reached higher levels than anyone could remember. About 93,000 square kilometers (36,000 sq mi) were affected. Throughout the Midwest almost 40,000 people were forced from their homes as rivers leading to the Mississippi flooded, too. Floodwater from a Mississippi tributary poured into Des Moines, Iowa, 200 kilometers (124 mi) from the Mississippi. It swept into the city’s water-treatment plant, cutting off the water supply for nearly two weeks. In all, crop loss and property damage were estimated at more than $10 billion. The flood claimed about 50 lives.
The flood demonstrated that even the best designed flood-control systems cannot always contain the Mississippi River. People cannot stop the natural cycle of flooding that has evolved over two million years. The flood has forced a debate over the value of flood control on the river. (Mississippi Flood, 1)
Flood-Control Measures Made Flooding Worse
Over the past seven decades, engineers have built a complex system of flood controls on the Mississippi. The engineers rely heavily on levees, embankments running alongside rivers. They hold the water within the river’s channel instead of letting it spread out over the floodplains. With its floodplains kept dry through engineering, the Mississippi River basin now yields about 40 percent of the total agricultural production of the United States. Moreover, engineering makes navigation on the river much easier.
Levees save lives and protect some fields and towns from complete flooding. Yet they can be dangerous. They increase the flood water’s pressure and depth. They can actually cause more damage by allowing floodwaters to build up in a narrow channel and then overcome weaker or lower levees downstream. During the 1993 flood, some levees were purposely destroyed to flood sparsely populated regions and save more populated areas. (Mississippi Flood, 1)
Together with the levees, a network of dams and reservoirs along the Mississippi’s drainage area can hold back usual amounts of water and even moderate amounts of floodwater. The water released from these structures cuts a deep channel for navigation. It also equalizes water levels. During major floods, however, there is often so much water that the levees and dams cannot control it.
People have changed the Mississippi’s natural ability to bounce back from floods. Wetlands, bends in the river, and open floodplains are natural means for storing floodwater. Construction of levees, dams, and reservoirs, and the straightening and deepening of the river have removed these natural flood-control measures. After the flood of 1993, where the water was controlled by human-made devices, water remained on fields in some places for more than six months. The standing water damaged farm production until the next full growing season.
Most of the plants and animals that live in the Mississippi River basin have adapted to floods. These species have lived through many floods in the past. As the floodwaters recede, their populations come back. It will be a long time, though, before the human population fully recovers from the damage brought by the flood of 1993. (Mississippi Flood, 1)
Factors in the Failure of Flood Control
Flood management has been a state-run apprehension for a long time, but overflow catastrophe assistance became a central subject when in 1927 the Great Flood hit. In the month of April that very year, the Mississippi River penetrated levees constructed by the Army Corps of Engineers to hold the river and support farming activities. The floodwaters took over an expansion about the magnitude of New England (only Maine can be minus), equal to a profundity of 30 feet. Floodwater distressed states from Pennsylvania to Oklahoma to; however, the actual calamity struck the lower Mississippi, from Cairo, Ill., deep into the Gulf of Mexico. Almost 1,000,000 people became dispossessed of homes and a number of people met tragic flood-caused deaths. (Clement, 1)
It was a countrywide misfortune, the state’s biggest flood tragedy-yet the central administration, whose shaken levees were extensively criticized for the tragedy since they had boasted a fake feeling of safety for the people who resided behind them, paid not even a cent in aid to the victims of the tragedy. As a substitute, neighboring churches arranged for clothes drives. The Red Cross provided food for almost 700,000 affected people for months.
The peopled stated that the efforts for these local aids were not sufficient. The entire country should stand for relief help. And history writers would the overflow “a watershed moment” in state psychology in the days to come. Previous to it, home states and communities had all the responsibility for downpour assistance efforts. After the year 1927, the responsibility was relayed to the central administration, both to thwart floods, and to help out the affected. Ever since 1927, as such, the national government has granted billions of dollars in flood assistance funds, largely via the Federal Emergency Management Agency (FEMA) and its precursor organization. Finance history writers indicate that this changeover from local to state-run liability in turn maintained what financial experts name it as “moral hazard,” the feeling that local groups would hereafter take higher perils in relation to overflowing than they in any other way could have been – permitting more expansion on the flood-plain, for instance – just as a proprietor may not be much cautious about fire chances if an indemnity corporation is going to pay back the homeowner if his house catches fire and burns up. (Clement, 1)
In the expectation that one more catastrophic overflow can be barred, the central government with the help of other organizations also increased to doubled its endeavors to manage the state’s rivers flowing protocols, adding mended levees with huge dams and basins intended to hold back water stream and floodway conduits enable managed openings for soaring water.
But the difficulty has not reduced. Actually, losses by flood in the United States of America progressively shot up throughout the 20th century. One analyst states that from between 1916 and 1985, the per capita damaged by floods in the United States of America went up by a part of 2.5 in steady dollars. One more analysis of whole flood damages places the present statistics at more than $6 billion yearly, a four-layered addition (in steady dollars) since the start of the 1900s. One more method to view the tendency is: during 1960 to 1985, when the central government expended 38 billion dollars on controlling floods, standard yearly flood losses (attuned to price rises) went more than twice. (Clement, 1)
The total of central government’s money used on adversity assistance is enormous. During the years from 1977 to 1993, in accordance with a 1998 General Accounting Office examination, central agencies expended almost 120 billion dollars on central catastrophe help, a great deal of it for flood calamities. Almost three-quarters of the whole amount was put to recovery efforts in the aftermaths of disaster striking. 21% of the whole budget was expended on dams and levees, and five percent was used on adversity training and reaction. Just two percent of the entire budget was employed to practical attempts to put off prospective calamities. (Clement, 1)
The breakdown of controlling floods and relieving people from aftermaths of flood became unhappily clear with the Midwest overflow of 1993, a tragedy which cost the country as large amount as 16 billion dollars. After assessing the 1993 overflow in the background of the nation’s sore past of efforts for controlling floods, a presidential advice-giving board issued a statement in July 1994 which required a complete repair of the policy of US flood control. Sen. Max Baucus of Montana appeared to be a principal supporter for the board’s proposals, discontinuing legislation that could have financed a number of old-standing flood management plans.
The rising viewpoint proposed that we ought to depend less on made-up dams and levees managing floods, and the so forth – because they cannot offer overall protection and may in fact add to the danger by giving fake assurance to proprietors and companies that place behind their defensive walls.
It was advised that public and their properties be shifted from the flood-expansion – the locales of uppermost danger, in order that they would not be in need to be saved and reconstructed after every consecutive tragedy. It suggested greater dependence on nonstructural resolutions, like reinstating quagmires which can work as normal dabs, taking in extra waters and breaking down pouring rains from getting to the rivers. (Clement, 1)
It also recommended developments in danger and liability control, encouraging inhabitants in flood-expansions to purchase insurance for flood and bringing in the regulations for zoning and maintaining systems that would defend against frequent reparation in prospective floods. Ever since then, a few government organizations at home, at state and central banks have shifted to ratify a few of these steps. Davenport, Iowa, for instance, chose to not construct a wall to hold back the river from their district and in its place constructed an expansion on the flood-related terrain. Central and state funds have been expended to bogs reinstatement. In Austin, Minn., 163 houses were enthused off the Minnesota River’s flood terrain, with monetary assistance from FEMA. And the insurance regulations for floods were stiffened to push more citizens to take it so more constructions would be saved. (Clement, 1)
But accomplishment of these degrees has been greasy, at best – partial by shortage of financial support and political determination. Furthermore, in the Ninth District, as somewhere else, constructing dams so as to prevent floods still continues the default option, a well-liked preparation selected by makers of decision partly owing to the fact that it appeared to be an instant, substantial solution and partly because federal money finance the expenditure. (Clement, 1)
Works Cited
Clement, Douglas. Fedgazette. The failure of flood control. Fedgazette. 2001. eLibrary.
Proquest CSA. ROBINSON SECONDARY SCH. 2008. Web.
Coffman, John Edwin. “Mississippi River.” World Book Online Reference Center. 2008. Web.
Lane, Ferdinand C. “Mississippi River.” Encyclopedia Americana. 2008. Grolier Online. Web.
When the earth moves in what we term an earthquake, it usually does so as a result of tectonic forces deep beneath the surface of the planet. In a strict definition of the term, earth movements triggered by volcanoes, nuclear blasts, mine explosions or meteor strike can also be termed earthquakes, but the earth manifests a means of movement that remained frighteningly mysterious to people for centuries. These are earthquakes caused by tectonic forces. Tectonic earthquakes are the result of movements of the earth’s tectonic plates on which rest all the continents and oceans. These plate boundaries do not follow the boundaries of the continents or oceans and can frequently be identified by lines of mountains or what are known as subduction zones. To understand earthquakes, one must understand the way that the earth moves, the way that scientists have learned to measure earthquakes and how these movements affect the planet.
Body
There are basically three types of movement along the plate boundaries: transform, divergent and convergent. When the plates move horizontally to each other, a person standing on the fault line may experience the land sliding past on the other side of the line as the plates pass by each other. This is a relatively smooth movement as long as there are no irregularities in the line. An example of this type of fault is the San Andreas Fault in California. Divergent faults are often characterized by the presence of volcanic or outgassing activity, breaking through or directly below the fault line. In this type of fault, the plates are spreading apart and new material is being created. Proof that magma is not the only material that might emerge at these zones of construction, locations such as the Mid-Atlantic Ridge are characterized more by the release of nitrates in what are termed ‘black smokers’ than they are by the release of magma. Finally, convergent boundaries are those boundaries that are coming together in some way, destroying land.
When plates come together in convergent zones, they have a few options of their own. One plate may begin to sink under the layer of the other plate or both plates may meet head on and sink in subduction zones causing deep rifts such as the Marianas Rift in the Pacific Ocean. They might also collide and move upward, causing huge mountain ranges. In most cases, one plate sinks under the other, usually causing trenches on the ocean side, whose denser material tends to sink under the more buoyant material of the continental plate and volcanic mountain ranges on the land side as materials in the subducted oceanic plate begins to heat up and escape upward through the continental material. An example of this type of plate convergence can be found in the Andes Mountain Range of South America as the Nazca plate subsides beneath it.
An earthquake causes two major types of seismic waves that move through the earth and cause damage. The first of these are body waves, which travel directly through rock and cause the vertical and horizontal displacement of the surface. This form of wave is essentially divided between the primary waves and the secondary waves. They can be measured from around the planet and help scientists to pinpoint the epicenter, or point of friction, that caused the earthquake where the most significant movement has been achieved. The primary waves can move through liquid and rock, but the secondary waves are not able to move through water. The reason for this is because these types of waves depend upon refraction to keep their energy. As either of these types of waves move through the rock, they are most affected by the type of material they are moving through. The second type of seismic wave is the surface wave. Like the body waves, these can also be divided into two main subgroups. In this case, they are called the Love waves and the Rayleigh waves. These move more like the ripples in water and exist only on the surface. They can also cause vertical and horizontal displacement but lose strength the further they are from directly above the epicenter. Again, one form is able to affect bodies of water, the Rayleigh waves which contain an element of vertical movement, and the other has little effect as the Love waves can only influence the horizontal placement of water boundaries.
When earthquakes happen, people have figured out different ways of measuring the intensity of the movement using these various waves. Seismometers are sensitive instruments that are able to record when the earth moves. Through a long history of complicated calculations and adjustments, the seismograph has been developed to illustrate the magnitude of an earthquake based on the strength and speed of the body waves and surface waves created. A scale developed in the 1930s to indicate earthquake strength is still referred to as the Richter scale on which an earthquake of 3 or lower is relatively unnoticeable by the average individual while a rating of 7 indicates a highly destructive and violent quake. By measuring these waves at various points on the earth and comparing them, scientists can pinpoint just where the earthquake originated and be able to determine with some degree of accuracy whether another quake is immediately eminent.
By understanding the various reasons why earthquakes happen and how they affect the planet, it is easier to understand complicated instruments such as the seismometer. As the plates of the world shift against each other in their constant movement between the magnetic poles or through other geologic forces, they have several options of how to adjust either passing each other by, destroying landmasses or creating new ones. These conflicts cause seismic motions to travel through the planet to greater or lesser intensities that can be measured by the seismometers and give scientists a clearer picture of the planet and the changes they might still anticipate.