Category: Volcano

Introduction

Volcanic eruptions occur when lava and gas are emitted from the volcanic vent. The most common effects of this explosion are population displacement when masses of people are sometimes forced to escape the flood of flowing lava. Volcanic explosions also lead to temporary food scarcity and frequent volcanic ash landslides known as Lahar. The most hazardous form of volcanic eruption is referred to as glowing avalanche. This occurs because the exploded mixture of volcanic hot liquefied rock and gas contents which has temperatures ranging from one thousand two hundred degrees is formed (Contributor, 2929). The overflowing fusion is formed mainly from pieces of rocks that melt as a result of high temperatures. The discharge flows down the perimeter of the volcano at a high speed of about 100 kilometers per hour and they can cover an area of about 10 km or even to 40 km from where they originated from (Contributor, 2929). This paper will concentrate on the eruption of the Mount St. Helens volcano, looking at its history, the explosion, the immediate consequences of the eruption, and the historic impact on the climate and human life.

Background

Mount St. Helens before the 1980 eruptions

(Pre-1980 Mount St. Helens with view of Mt. Hood to the left., 2020) Mount St. Helens is a volcanic mountain situated in the state of Southwest Washington. It is the Cascade Ranges most active volcano, a mountainous region that ranges from British Columbia to northern California, across Washington and Oregon. Mount St. Helens has alternated between intervals of volcanic explosions and prolonged periods of relative calm for many years. It is an active stratovolcano and is 2,539 m (8,330 ft.) above sea level in height, and it is a dacite volcano (Contributor, 2020). Dacite is a type of igneous rock with a middle to high silica concentration of the source lava/magma, which is flammable and explosive when it explodes on the surface.

As a part of the Cascade Mountains, St. Helens and its corresponding volcano are the culmination of the volcanic activity of the Juan de Fuca Plate under the North American Plate. The molten rocks of the collapsing Juan de Fuca Plate fuel the magma channels of the volcanoes in the Cascade Range, including that of the Mountain. It is suspected that the volcano was created from four eruptive phases, beginning 275,000 years ago (Contributor, 2020). It is the most active volcano in the Cascade during the Holocene period.

Eruption

Mount St. Helens after the 1980 eruption

At the beginning of the 1980s, magma began pouring into Mt. St. Helens, prompting the volcano to protrude. The magma protrusion continued to develop until it became fragile, and the bulge and part of the summit collapsed into a debris avalanche. The pressure that had been building was released during an eruption which included small quantities of andesite/dacite magma. Not long after the explosion, there was a massive Plinian eruption of ash and tephra. Many minor earthquakes occurred prior to the outburst of ash in March 1980, when some of the volcanos pressure was released. It continued to have minor eruptions until the main one of May 1980. This major activity resulted in a massive mushroom cloud of ash depositing 520 million tons of ash over 22,000 square miles. The eruption reached 1,300 feet from the bottom of the volcano and destroyed the surrounding landscape (Usgs.gov., 2020). The massive emission of ash resulted in the emergence of lahar in rivers near the volcano.

Lahars are mudflows that are composed of alluvial deposits and water mud. They typically occur with glaciers on or around volcanoes. They can happen with volcanic activity, melting glaciers rapidly due to the heat of the outburst. They are some of the most dangerous volcanic hazards and are able to fly 40-50 miles per hour (Contributor, 2020). Lahars triggered by the 1980 explosion of Mt. St. Helen damaged 185 kilometers of road and 200 residences (Contributor, 2929). Events such as this have happened previously in this region and will occur in the future. It was in the year 2005 when Mt. St. Helens last erupted.

Pyroclastic Flows

Pyroclastic flows produce a high-density mixture of hot lava blocks, pumice, ash, and molten gas. They pass at an extremely high speed down the volcanic slopes, and along the valleys. Well before St. Helen exploded, pyroclastic flows rose from the top of the volcano, releasing a mixture of hot sedimentary rocks and gasses created by the dark fiery clouds. According to scientific discoveries, anyone close to the Pyroclastic explosion would have died immediately from the high temperatures of lava, ash, pumice, and gas, which could be up to 1300*F (Contributor, 2020). The flow is what killed all forms of life below the mountains surroundings. This helped pave the way for a completely new environment following the eruption of St. Helen.

Immediate Effects of the Eruption

The eruption caused tremendous damage to both property and humanity. A total of 57 individuals were killed and over 200 homes were burned (Contributor, 2020). Victims died from the inhalation of hot volcanic ash by asphyxiation, and others from thermal exposure and other injuries (Contributor, 2020). Lateral blasts, rubble tidal waves, mudflows, and floods caused extensive destruction to the land and civil works. All houses and related man-made constructions in the immediate area of Spirit Lake were submerged. The cloud of smoke and gas managed to reach 15 miles into the atmosphere, leaving the ash in a dozen regions. The transport infrastructure was seriously affected by the devastation and destruction of more than 185 miles of rail and highways, and the drainage networks were clogged with ash throughout the Northwest. Damage to farmland, civil infrastructure and timber was projected at $1.1 billion. The U.S. government allocated $950 million in emergency funds to assist with restoration and rehabilitation, which took ten weeks to finish the clearance of ash in the areas affected (Contributor, 2020). Until now, the territory all around the volcano is still rebounding from the impacts.

Historical Impacts

The planet had little pre-eruption knowledge prior to the St. Helen catastrophe. There was no way of determining volcanic disturbances. All this, though, changed in the wake of St. Helens. During the eruption disturbance gradients involved avalanches, mudflows, lateral blasts, tephra fall and pyroclastic flow. This has offered scientists a tremendous amount of study and analysis. While the St. Helens eruption was devastating, it helped make scientific and ecological advancement possible. Brand plants and other different species started to grow and flourish in a brand-new environmental setting which was never possible previously (Contributor, 2020). Owing to this the scientific world was able to make progress like never before. In the area of natural disaster science, society has started to gain more awareness.

Conclusion

Initially, the eruption of Mount Saint Helen Volcano was thought to be an earthquake, but later on, turned into one of the most destructive and devastating volcanic activities not only in the U.S. but worldwide as well. The explosion of the Mt. St. Helens Volcano would forever affect the worlds understanding of how to assess future seismic events and to assist in the safety of population living near or in those hazardous areas. Throughout the years, slight volcanic activities continue to follow. Many experiences from this specific incident have been realized, enabling the U.S. government, as well as other nations, to take early precautions in anticipation of such catastrophic events.

References

Contributor, M., (2020). Mount St. Helens Eruption: Facts & Information. LiveScience. Web.

Usgs.gov. (2020). Post-1980 Mount St. Helens with View of Mt Hood to the Left. [online] Web.

Science

Hello, my fellow students. My name is ABC, and I have chosen ‘Volcano and Aurora in Iceland’ as my topic. I have chosen the unique picture because it contains two natural events that occurred simultaneously, i.e. an aurora and a volcano. The picture was taken in 1991at the time when the two natural events were occurring. When negatively or positively charged particles in the atmosphere collide with neutral atoms in the thermosphere, natural light is given out. The natural light seen in the sky is known as an aurora. A volcano occurs when hot materials are released from below the surface of the earth along with weak points. Volcanoes have been shown to occur where tectonic plates diverge or converge. An extinct volcano has no predicted future activity while a dormant volcano could erupt in the future (no particular time). An active volcano has predicted times of erupting shortly. Some natural landmarks have been formed through volcanic activities.

The picture shows a scenario in which the earth and heaven opened up at the same time. In other words, the volcano Hekla was erupting from the surface of the earth while the natural light (aurora) was shining from the sky. It was like the volcano was lit so that it could erupt smoothly. It was a rare event witnessed in Iceland in 1991. It was estimated that the aurora in the picture was about 100 kilometers from the hot materials of the volcano. Hekla is an active volcano whose past volcanic activities have caused great destruction. However, its last eruption occurred about 33 years ago, and it caused minor destruction. It could be interesting to know whether auroras and volcanoes are witnessed only on the earth.

Responses

Hello Erick!

Thank you for your comment. Well, it is not known when a volcano and an aurora will occur again simultaneously in Iceland. The two events are random, and scientists have not been able to predict when they would occur. However, an aurora has higher chances of occurring than a volcano because negatively or positively charged particles in the atmosphere collide frequently with neutral atoms in the thermosphere. On the other hand, a volcano takes a long time to erupt, and it could be difficult to predict its activity. The other places where the events could be seen at the same time could be in the Arctic and Antarctic regions. The places should have an erupting volcano which should occur at the same time as an aurora.

I hope I have answered your two questions well.

Hi Beatriz!

I like your comment, Beatriz. Well, there is no other time when the two events have been documented to have occurred together. The events are so rare and random that not even the best scientists have been able to predict their occurrences. However, there is a high chance that the two natural events will occur again at the same time in the Arctic and Antarctic regions in the future.

I hope I have answered your question.

Hello Amanda!

The two events are quite random and unpredictable. It could be any size of a volcano, and it could happen anywhere on earth, particularly in the Arctic and Antarctic regions. As you have noted, the scenario is quite fascinating.

I hope I have answered your two questions.

Introduction

The proposed trip includes three stops. First, the Haleakalā volcano will be visited (see fig. 1). Then, we will get to the Wai’anapanapa State Park, which will take around 2 hours 40 minutes (see fig. 4). The landscapes should make up for this inconvenience. The Wai’anapanapa lava tube springs (see fig. 2) and black sand beach (see fig. 3) are the two other features of the trip. All the stops are popular touristic sites, which is why they have the entire necessary infrastructure. The specifics of the sites will be investigated as discussed below.

Stop 1: Haleakalā Volcano

Haleakalā is a large shield volcano that is situated in the east of the Island of Maui and basically comprises this part of Maui. Its name is translated as the “House of the Sun.” Having been created by the Hawaiian hot spot, it rises from the ocean floor; its height above the sea level is 3,005 meters, which amounts to about 7% of its true size. It is also 53 kilometers across with the crater of 49 kilometers, and it makes up about 70% of the Island of Maui (Lopes, 2005, p. 98).

The plate tectonic theory explains the creation of volcanoes by studying the movements of tectonic plates that are rigid lithosphere parts (Wicander, 2013, p. 11). Hawaii Islands are not situated on a boundary that would allow the plates to collide or separate. Instead, they are the result of the Pacific plate movement over the “hot spot” or “mantle plume” that has created the volcanoes, which produced the islands (Wicander, 2013, p. 54). Therefore, Haleakalā is one of the volcanoes that have been formed in the middle of a plate by a hot spot. The volcano was also enlarged by erosion to the size that we are introduced to during the trip (Lopes, 2005, p. 98).

The volcano is currently in the non-eruptive phase, and it is being monitored. Its latest eruption took pace in the seventeenth or eighteenth century (Coastal Geology Group, 2013; Lopes, 2005). The earthquakes that are being registered are not considered to be the result of its activity, but it is not excluded that it may erupt again (Lopes, 2005, p. 105).

The volcano (and volcanoes in general) has its economic uses. In particular, it has become a tourist attraction, which contributes to the economic development of the island. Similarly, the specific natural features of a great part of Maui (including the following two stops that will be visited during this trip) are the results of its activity. The volcano also has produced resources (for example, basalt), which can also be regarded as a benefit (Lopes, 2005). To sum up, the Island of Maui would not exist in the way that we know it today without Haleakalā.

Stop 2: Wai’anapanapa Spring

Wai’anapanapa State Park is rich with varied features. Among them are the springs that are located in its large lava tubes and filled with groundwater (Lopes, 2005). These lava tubes are the results of a relatively common phenomenon: the solidification of the “peripheral portions” of a moving lava stream. The results are peculiar stalactites and “shelves.” Most of the tubes lack the “ceiling” or have holes in it, which indicates that these parts of the formation must have remelted (Ziegler, 2002, p. 5). At a point after their formation, groundwater flooded the tubes, and they became a popular swimming place (Lopes, 2005).

The water in the tubes of Wai’anapanapa Park is fresh and pure; it can be considered a part of groundwater resources of Maui (Lopes, 2005). In this particular area, the springs are used for swimming and as a tourist attraction. In general, Maui uses groundwater resources for consumption, works to manage them effectively and aims to protect them. Still, as the result of the usage, the level of the groundwater has declined, and the chloride concentrations have risen (US Department of the Interior, 2010). Apart from that, the water has been polluted with other substances, in particular, agricultural waste (Naie & McMahon, 2011).

The government of Maui endeavors to research new, more effective techniques of using groundwater (US Department of the Interior, 2010). The need for the development of such techniques is explained by the fact that groundwater is the principal source of the domestic water supply of Maui (Naie & McMahon, 2011). In particular, the Iao and Waihee aquifer areas provide water for the entire island (US Department of the Interior, 2010, par. 1).

Naie and McMahon (2011) mention the drawbacks of using well and aquifer water: they are concerned with “high cost of pumping, lack of public land for well sites, agricultural pollutants in many aquifers, permitting and the expense of infrastructure installation to relatively remote well sites” (para. 7). Still, despite these issues, the economic benefit of using groundwater cannot be denied: this is a valuable resource that in necessary for the future of the island and requires proper management (US Department of the Interior, 2010).

Stop 3: Wai’anapanapa Black Sand Beach

The Wai’anapanapa black sand beach Pa’iloa is a part of the Hana shoreline that is generally characterized by steep and rocky headlands, high cliffs, and small islands (Coastal Geology Group, 2013). Pa’iloa also features cliffs and lava rocks; apart from that, it can be used to watch a variety of sea birds. The black sand is the product of the wave-caused erosions of the basaltic lava cliffs in the area, which, in turn, are the products of the island’s past volcanic activity (Lopes, 2005).

According to Norcross-Nu’u, Fletcher, and Abbott (2008), the primary issue of modern Maui beaches is erosion, and humans have contributed to the problem by exploiting natural resources. Still, not all the parts of Maui shoreline are equally developed and exploited, and the Wai’anapanapa State Park is relatively untouched and protected, even though it is a full-fledged touristic attraction now (Derrick & Derrick, 2006).

The island proceeds to develop its understanding of coastline and, in particular, beach management (Coastal Geology Group, 2013). The health of a beach defines that of the area and its wildlife, and Maui government employs the following techniques to preserve its beaches: monitoring, individual management, and contemporary interventions that are mindful of the possible consequences for nearby nature (Norcross-Nu’u et al., 2008). The key technique that Norcross-Nu’u et al. (2008) describe is the beach nourishment (replenishment of the sand of an eroded beach); as for other methods, they insist on an individual approach to varied areas of Maui.

The island of Maui is “composed of two large volcanoes” (Coastal Geology Group, 2013, para. 1). One of them, the West Maui Volcano, is extinct, but Haleakalā is dormant. The island is still setting on the ocean floor (its speed is several centimeters per year), which occasionally leads to small earthquakes (Lopes, 2005, p. 105). This process “moves” the Hawaii Islands over their “hot spot.” As a result, the islands do not appear at a plate boundary, but on one of the plates (the Pacific one), and their creation and volcanic activity are explained by the existence of a “stationary mantle plume” in the area (Wicander, 2013, p. 54). The existence of the Islands demonstrates the variety of natural phenomena that can lead to similar outcomes.

References

Coastal Geology Group. (2013). Maui. Web.

Derrick, J., & Derrick, N. (2006). Mau’i mile by mile. Columbia, S.C.: Hawaiian Style.

Lopes, R. (2005). The volcano adventure guide. Cambridge: Cambridge University Press.

Naie, L., & McMahon, M. (2011). Maui’s water resources: A general overview. Web.

Norcross-Nu’u, Z., Fletcher, C., & Abbott, T. (2008). Beach management pan for Maui. Web.

US Department of the Interior. (2010). Recent hydrologic conditions, Iao and Waihee aquifer areas, Maui, Hawaii. Web.

Wicander, R. (2013). Historical geology. Belmont, CA: Brooks/Cole Cengage Learning.

Ziegler, A. (2002). Hawaiian natural history, ecology, and evolution. Honolulu: University of Hawai’i Press.

Geological Features and Events

• Most of the features on the Hawaii formed primarily as a result of volcanic eruptions in the region.
• The most prominent of these features are volcanoes.
• All the volcanoes in Hawaii are shield volcanoes. They are large and have shallow-sloping sides – almost like a warrior’s shield.
• The volcanoes of the region are formed by low-viscosity lava .
• All the volcanoes in Hawaii are shield volcanoes. They are large and have shallow-sloping sides – almost like a warrior’s shield
  • They are formed by low-viscosity (very runny) lava which, over time, runs down the side of the volcanic mountain and builds up a broad profile
  • It is like as if you had a steep, tall mountain of sand and you poured more sand on top of the mountain. The sand would run down the sides and, if you pour enough sand, your once steep and tall mountain will now be a shallow and broad hill.
  • The shield volcanoes Hawaii erupt magma as hot as 1,200 °C (2,200 °F) compared with 850 °C (1,560 °F) for most other volcanoes around the world (Garcia et al., 2000).
  • The Big Island of Hawaii is totally made up of volcanoes.
  • From oldest to youngest these are:
    • Kohala
    • Mauna Kea
    • Hualalai
    • Mauna Loa
    • Kilauea
• Kilauea is one of the world’s most active volcanoes.

Geological Feature

Volcanoes are the most prominent features in the region. The most common parent rock material in Hawaii is the extrusive igneous rock.

The minerals that make up the extrusive igneous rocks found in the region include:

• Quartz
• Pyroxene
• Feldspar
• Mica
• Hornblende

The most common parent rock material in Hawaii is the extrusive igneous rock (Clark, 1989).

• Basalts are dark colored, fine-grained extrusive rock.
• Dacite The principle minerals that make up dacite are plagioclase, quartz, pyroxene, or hornblende.
• Gabbro- It is composed mostly of the mineral plagioclase feldspar with smaller amounts of pyroxene and olivine.
• Granite- Its minerals are quartz, feldspar, mica, and usually hornblende.
• Obsidian is a very shiny natural volcanic glass. It is produced when lava cools very quickly.
• Pumice is a very light colored, frothy volcanic rock. Pumice is formed from lava that is full of gas.
• Rhyolite is very closely related to granite. The difference is rhyolite has much finer crystals. The minerals that make up rhyolite are quartz, feldspar, mica, and hornblende.

Geologic Time

The volcanoes of Hawaii are much newer, in terms of geological time.

Since it is known that the volcanoes in Hawaii are growing and their sizes are also known, their ages can be determined by simple calculations.

The volume of the oldest volcano (Kilauea) is divided by the rate of growth upto now.

Flows from last 20 years covered ~20% of Kilauea and are ~ 1-2 m thick.

Kilauea is at least 5000 m above the adjacent sea floor.

(1 m / 5000 m)/20 yrs = 1/100,000 years
(2 m / 5000m)/20 yrs = 1/50,000 years

So, it took 50,000-100,000 years to build 20% of Kilauea.

Thus, it took 250,000-500,000 years to build all of Kilauea.

• The island of Hawaii is much newer, in terms of geological time, and its volcanoes still spewing lava periodically.
• It took 250,000-500,000 years to build all of Kilauea. This is arrived at by simple mathematics.
• We know Kilauea is growing and it is known how big it is.
• If we can work out how fast it grows we can just divide the volume by the growth rate to get the age.
• Flows from last 20 years covered ~20% of Kilauea and are ~ 1-2 m thick (Fletcher, & Jones, 1996).
• Kilauea is at least 5000 m above the adjacent sea floor.
• (1 m / 5000 m)/20 yrs = 1/100,000 years
• (2 m / 5000m)/20 yrs = 1/50,000 years
• So, it took 50,000-100,000 years to build 20% of Kilauea.
• Thus, it took 250,000-500,000 years to build all of Kilauea.

Assumptions

• Things happened the same way in the past as they do now (uniformity of process).
• Things happened at the same speed in the past as they do now (uniformity of rate).

Geological Event

• Hawaii volcanoes are built by thousands of accumulated lava flows.
• Eruptions in the Hawaiian volcanoes are usually preceded by a series of earthquakes.
• These earthquakes open fissures and allow magma to reach the surface.

Plate Tectonics

• The Earth’s plates are in constant, but very slow, motion.
• A hot spot is a point on the Earth’s surface where unusually hot magma impinges on the base of the lithosphere.
• The volcanic mountains creating the Hawaiian islands are among the greatest mountain ranges on earth.
• They rise an average of 4,572 meters (15,000 feet) to reach sea level from their base on the sea floor with the highest (Mauna Loa) climbing an additional 4,170 meters (13,680 feet) above sea level.
• As shield volcanoes, they are built by thousands of accumulated lava flows growing no more than 3 meters (10 feet) at a time to form a broad, gently sloping, flat domed volcanic cone (Clark, 1989).
• Eruptions in the Hawaiian volcanoes are usually preceded by a series of earthquakes which open fissures and allow magma to reach the surface.
• Initially lava fountains, known as “curtains of fire,” hurl streams of lava hundreds of feet into the air from many points along the fissure.
• Hawaiian flows are considered to issue forth relatively quietly since the lava is quite fluid, and the gases escape readily without the disruption of the lava into ash or cinders
• Great floods of lava will then flow down the mountainside.
• Eruptions last from a few days to ten months, frequently followed in two or three years by a flank eruption.

Plate tectonics

• The Earth’s plates are in constant, but very slow, motion.
• Their speed vary with the fastest moving at ten times the rate of the slowest.
• The fastest-moving plates are the oceanic plates, with the Cocos plate having the highest velocity at 8.6 cm per year.
• The giant Pacific plate is the second fastest, moving at 8.0cm per year.
• The slowest-moving plates are the continental plates, because of deep roots which slow their movement.
• They move at a speed of between 0.7cm and 1.1cm per year.
• A hot spot is a point on the Earth’s surface where unusually hot magma impinges on the base of the lithosphere.
• Because the magma from the core is very much hotter than ‘normal’ mantle material, it is lighter, and rises up through the whole of the mantle thickness to impinge on the base of the lithosphere where it melts the rigid rock .
• This molten rock may reach the Earth’s surface by ejection from volcanoes.
• The Hawaiian islands result from a mantle plume impinging on an oceanic plate, which is moving relatively rapidly, and simply ‘floats over’ the hot spot.

Weathering and Erosion

• Volcanic mountains are subject to the effects of erosion.
• Unless lava continues to flow, the whole mass could wear away.
• Erosion happens mainly as a result of weathering – the effect of water (Mechanical weathering), temperature and wind on the landscape.
• Water causes much erosion. When it falls as acid rain, it can dissolve rocks that are sensitive to acid.
• After volcanic mountains reach the surface, they are subject to the effects of erosion (Moore, 1987).
• Unless lava continues to flow, the whole mass could wear away.
• Erosion happens mainly as a result of weathering – the effect of water, temperature and wind on the landscape.
• Erosion is a key part of the Rock Cycle.
• It is responsible for forming much of the interesting landscape that is around Hawaii mountains.
• Water causes much erosion.
• When it falls as acid rain, it can dissolve rocks that are sensitive to acid.
• Marble & limestone weather when exposed to the rain.
• When the rain falls very heavily, as in monsoons, then flooding can happen.

Igneous Rocks

• Lava flowing from a volcano in Hawaii forms igneous rocks.
• In Hawaii, the igneous rocks are the most predominant type.
• Igneous rocks are black when young and turn brown when old.
• The igneous rocks are generally dark due to a high iron and magnesium content.
• Lava flowing from a volcano in Hawaii. forms igneous rocks (MacDonald et al., 1986).
• In Hawaii, this are the igneous rocks are the most predominant.
• Most of these igneous rocks are black or gray when young and turn brown-to-red when old and weathered.
• The lava in Hawaii owes its dark colors to a high iron and magnesium content.
• As it ages, oxidation of the iron creates the orange and red hues.

Sedimentary Rocks

Sedimentary rocks are formed in three steps:

• Layers of sediment are deposited at the bottom of seas and lakes.
• Over millions of years the layers get squashed by the layers above.
• The salts that are present in the layers of sediment start to crystallize out as the water is squeezed out.

Examples of sedimentary rocks:

• Sandstone
• Mudstone or shale
• Limestone
• Conglomerate

• Sedimentary rocks are formed in three steps:
• Layers of sediment are deposited at the bottom of seas and lakes.
• Over millions of years the layers get squashed by the layers above.
• The salts that are present in the layers of sediment start to crystallize out as the water is squeezed out.
• These salts help to cement the particles together
• Sedimentary rocks will often have layers or bands across them.
• It will often contain fossils which are fragments of animals or plants preserved within the rock. Only sedimentary rocks contain fossils.
• The rock will tend to scrape easily and often crumble easily.

Metamorphic Rocks

• Metamorphic rocks are the least common in Hawaii volcanoes
• Metamorphic rocks are igneous or sedimentary rocks that have been transformed by great heat or pressure
• When the earth’s crust moves, it causes to get squeezed so hard that the heat causes the rock to change.
• Marble is an example of a sedimentary rock that has been changed into a metamorphic rock

• Metamorphic rocks are rocks that have changed.
• The word comes from the Greek “meta” and “morph” which means to change form.
• Metamorphic rocks were originally igneous or sedimentary, but due to movement of the earth’s crust, were changed.
• When the earth’s crust moves, it causes rocks to get squeezed so hard that the heat causes the rock to change.
• Marble is an example of a sedimentary rock that has been changed into a metamorphic rock.
• Metamorphic rocks are the least common of the 3 kinds of rocks.
• Metamorphic rocks are igneous or sedimentary rocks that have been transformed by great heat or pressure.
• Foliated metamorphic rocks have layers, or banding.
• Slate is transformed shale. It splits into smooth slabs.
• Schist is the most common metamorphic rock.
• Gneiss has a streaky look because of alternating layers of minerals.
• Mica is the most common mineral.
• Non-foliated metamorphic rocks are not layered.
• Marble is transformed limestone.
• Quartzite is very hard.

Water, Desert, and Glaciers

• 36 square miles of Hawaii are covered by water
• Hawaii is protected by the high cliffs of the mountains with waterfalls falling into the ocean
• The Kau Desert which is part of Hawaii Volcanoes National Park. It is formed by the rain shadow which leaves one side of the mountain relatively dry
• Geologists have long recognized deposits formed by glaciers on Mauna Kea during recent ice ages
• 36 square miles of Hawaii are covered by water (Moberly Jr., 1963).
• The north and southeastern coast of Hawaii is protected by high cliffs with waterfalls falling over the edge into the ocean below
• Thousands of gently sloping basaltic lava flows that comprise the bulk of the island volcanoes are a vital part of hawaiis water resources
• The structural features associated with these flows such as voids between flows, shrinkage fractures, lava beds make rocks highly permeable hence water storage regions.

The Kau Desert which is part of Hawaii Volcanoes National Park is formed by the rain shadow.

As the volcanic mountains drive the wet air up as the trade winds and force it to drop out the water as rain so the air on the other side of the mountain is relatively dry.

Geologists have long recognized deposits formed by glaciers on Mauna Kea during recent ice ages.

The latest work indicates that deposits of three glacial episodes since 150,000 to 200,000 years ago are preserved on the volcano

Resources

• The Hawaiian Islands are created by volcanoes
• The active and dormant volcanoes of Hawaii are an integral part of the lives of the people who live there
• Eruptions by virtue of the fact that they are a rare occurrence attract a lot of tourists to the island
• The unique landscapes and water features also attract tourism revenue
• Volcanoes harbor a lot of mineral resources most of which are exported to other countries
• The Hawaiian Islands are created by volcanoes.
• The active and dormant volcanoes of Hawaii are an integral part of the lives of the people who live there
• The unique landscapes and eruptions by virtue of the fact that they are a rare occurrence attract a lot of tourists to the island, hence increased revenue to the people who live there
• Volcanoes produce a lot of mineral resources most of which are exported to other countries where they are used to produce a number of important commodities. These exports contribute to the revenue of the region.

Conclusion

• The Hawaii series of volcanoes was chosen for this presentation
• This is because it has one of the most active volcanoes in the world
• The Hawaii volcanoes were also chosen as a topic of discussion because of the broad nature of the features in the area. For instance, it is very difficult to find an individual feature that has a desert and glaciers all in the same region
• In conclusion, It is worth noting that the Hawaii range of volcanoes is a large area with varied features and cannot be exhaustively discussed in one sitting
• The Hawaii series of volcanoes was chosen for this presentation
• This is because it has one of the most active volcanoes in the world
• The Hawaii volcanoes were also chosen as a topic of discussion because of the broad nature of the features in the area. For instance, it is very difficult to find an individual feature that has a desert and glaciers all in the same region
• In conclusion, It is worth noting that the Hawaii range of volcanoes is a large area with varied features and cannot be exhaustively discussed in one sitting

Introduction

Volcanic eruptions occur when lava and gas are emitted from the volcanic vent. The most common effects of this explosion are population displacement when masses of people are sometimes forced to escape the flood of flowing lava. Volcanic explosions also lead to temporary food scarcity and frequent volcanic ash landslides known as Lahar. The most hazardous form of volcanic eruption is referred to as ‘glowing avalanche.’ This occurs because the exploded mixture of volcanic hot liquefied rock and gas contents which has temperatures ranging from one thousand two hundred degrees is formed (Contributor, 2929). The overflowing fusion is formed mainly from pieces of rocks that melt as a result of high temperatures. The discharge flows down the perimeter of the volcano at a high speed of about 100 kilometers per hour and they can cover an area of about 10 km or even to 40 km from where they originated from (Contributor, 2929). This paper will concentrate on the eruption of the Mount St. Helens volcano, looking at its history, the explosion, the immediate consequences of the eruption, and the historic impact on the climate and human life.

Background

Mount St. Helens before the 1980 eruptions

(Pre-1980 Mount St. Helens with view of Mt. Hood to the left., 2020) Mount St. Helens is a volcanic mountain situated in the state of Southwest Washington. It is the Cascade Range’s most active volcano, a mountainous region that ranges from British Columbia to northern California, across Washington and Oregon. Mount St. Helens has alternated between intervals of volcanic explosions and prolonged periods of relative calm for many years. It is an active stratovolcano and is 2,539 m (8,330 ft.) above sea level in height, and it is a dacite volcano (Contributor, 2020). Dacite is a type of igneous rock with a middle to high silica concentration of the source lava/magma, which is flammable and explosive when it explodes on the surface.

As a part of the Cascade Mountains, St. Helens and its corresponding volcano are the culmination of the volcanic activity of the Juan de Fuca Plate under the North American Plate. The molten rocks of the collapsing Juan de Fuca Plate fuel the magma channels of the volcanoes in the Cascade Range, including that of the Mountain. It is suspected that the volcano was created from four eruptive phases, beginning 275,000 years ago (Contributor, 2020). It is the most active volcano in the Cascade during the Holocene period.

Eruption

Mount St. Helens after the 1980 eruption

At the beginning of the 1980s, magma began pouring into Mt. St. Helens, prompting the volcano to protrude. The magma protrusion continued to develop until it became fragile, and the bulge and part of the summit collapsed into a debris avalanche. The pressure that had been building was released during an eruption which included small quantities of andesite/dacite magma. Not long after the explosion, there was a massive Plinian eruption of ash and tephra. Many minor earthquakes occurred prior to the outburst of ash in March 1980, when some of the volcano’s pressure was released. It continued to have minor eruptions until the main one of May 1980. This major activity resulted in a massive mushroom cloud of ash depositing 520 million tons of ash over 22,000 square miles. The eruption reached 1,300 feet from the bottom of the volcano and destroyed the surrounding landscape (Usgs.gov., 2020). The massive emission of ash resulted in the emergence of lahar in rivers near the volcano.

Lahars are mudflows that are composed of alluvial deposits and water mud. They typically occur with glaciers on or around volcanoes. They can happen with volcanic activity, melting glaciers rapidly due to the heat of the outburst. They are some of the most dangerous volcanic hazards and are able to fly 40-50 miles per hour (Contributor, 2020). Lahars triggered by the 1980 explosion of Mt. St. Helen damaged 185 kilometers of road and 200 residences (Contributor, 2929). Events such as this have happened previously in this region and will occur in the future. It was in the year 2005 when Mt. St. Helens last erupted.

Pyroclastic Flows

Pyroclastic flows produce a high-density mixture of hot lava blocks, pumice, ash, and molten gas. They pass at an extremely high speed down the volcanic slopes, and along the valleys. Well before St. Helen exploded, pyroclastic flows rose from the top of the volcano, releasing a mixture of hot sedimentary rocks and gasses created by the dark fiery clouds. According to scientific discoveries, anyone close to the Pyroclastic explosion would have died immediately from the high temperatures of lava, ash, pumice, and gas, which could be up to 1300*F (Contributor, 2020). The flow is what killed all forms of life below the mountain’s surroundings. This helped pave the way for a completely new environment following the eruption of St. Helen.

Immediate Effects of the Eruption

The eruption caused tremendous damage to both property and humanity. A total of 57 individuals were killed and over 200 homes were burned (Contributor, 2020). Victims died from the inhalation of hot volcanic ash by asphyxiation, and others from thermal exposure and other injuries (Contributor, 2020). Lateral blasts, rubble tidal waves, mudflows, and floods caused extensive destruction to the land and civil works. All houses and related man-made constructions in the immediate area of Spirit Lake were submerged. The cloud of smoke and gas managed to reach 15 miles into the atmosphere, leaving the ash in a dozen regions. The transport infrastructure was seriously affected by the devastation and destruction of more than 185 miles of rail and highways, and the drainage networks were clogged with ash throughout the Northwest. Damage to farmland, civil infrastructure and timber was projected at $1.1 billion. The U.S. government allocated $950 million in emergency funds to assist with restoration and rehabilitation, which took ten weeks to finish the clearance of ash in the areas affected (Contributor, 2020). Until now, the territory all around the volcano is still rebounding from the impacts.

Historical Impacts

The planet had little pre-eruption knowledge prior to the St. Helen catastrophe. There was no way of determining volcanic disturbances. All this, though, changed in the wake of St. Helen’s. During the eruption disturbance gradients involved avalanches, mudflows, lateral blasts, tephra fall and pyroclastic flow. This has offered scientists a tremendous amount of study and analysis. While the St. Helens eruption was devastating, it helped make scientific and ecological advancement possible. Brand plants and other different species started to grow and flourish in a brand-new environmental setting which was never possible previously (Contributor, 2020). Owing to this the scientific world was able to make progress like never before. In the area of natural disaster science, society has started to gain more awareness.

Conclusion

Initially, the eruption of Mount Saint Helen Volcano was thought to be an earthquake, but later on, turned into one of the most destructive and devastating volcanic activities not only in the U.S. but worldwide as well. The explosion of the Mt. St. Helens Volcano would forever affect the world’s understanding of how to assess future seismic events and to assist in the safety of population living near or in those hazardous areas. Throughout the years, slight volcanic activities continue to follow. Many experiences from this specific incident have been realized, enabling the U.S. government, as well as other nations, to take early precautions in anticipation of such catastrophic events.

References

Contributor, M., (2020). Mount St. Helens Eruption: Facts & Information. LiveScience. Web.

Usgs.gov. (2020). Post-1980 Mount St. Helens with View of Mt Hood to the Left. [online] Web.

This theory postulates that iron from the volcanic ash fertilizes the sea and enhances excessive growth of phytoplankton thus providing food for zooplankton and small fishes, which in turn become food for salmon. This theory explains why there is excessive growth of salmon in rivers of British Colombia and Canada following a volcanic eruption, which occurred on the Kasatochi Island. This theory sparks a lot of controversies internationally as to whether or not to fertilize the sea with iron to boost dwindling fish stocks.

Supporting this theory, the population of salmon fishes in 2009 was very low as compared to the excessive numbers in 2010 in Fraser River in British Columbia. The leading proponent of this theory who is also an eminent fisheries research scientist, Tim Parsons argues that ash from volcanic eruptions contains iron which indirectly enhances the excessive growth of salmon. Other fisheries scientists support Parsons’s school of thought because of his great experience in oceanic sciences that earned him a medal from the Canadian government. Another research scientist, David Welch says that practical determination of the salmon growth is by checking seasonal growth of scales and comparing 2010 and 2008 growth if there are any significant differences in their growth.

Opponents of the theory such as Carl Walters dismiss the arguments saying that the theory is as good as any theory meaning there is nothing new or interesting about it. He further argues that the practical determination of the seasonal scales will not give a significant difference to support the theory. Since salmon fishes depend on zooplankton and small fishes as their food, it is, therefore, unrealistic to attribute their bloom just one month after volcanic eruption because of the growth of zooplankton and small fishes take several months to a year to reproduce even though there is evident phytoplankton bloom. Moreover, if the volcanic eruption is the cause of the salmon glut experienced in the Fraser River, the same scenario should replicate itself in another place where volcanic eruptions are prone.

Scientific research has confirmed that iron is a necessary mineral for the growth of phytoplankton; the primary producer of food in the sea or ocean. Phytoplanktons are food to small fishes and zooplankton, which in turn form the main food of the salmon fishes. The low population of the salmon fishers in the Northern Pacific Ocean is due to the limited amount of iron in water but recent volcanic eruptions and dust from Asian deserts are increasing the concentration of iron in the North Pacific Ocean. The theory is credible because, in places where volcanic eruptions had occurred, there was a subsequent increase in the population of salmon several years after.

Although the theory gives a plausible biological explanation for the excessive growth of salmon in the North Pacific Ocean, it will prompt fish industries to add iron deliberately into the oceans to increase fish reproduction posing unforeseen danger in marine life. There is a fear that big companies formulated the hypothesis for them to dump huge amounts of iron into the sea as a means of regulating climate. However, for the theory to be credible the volcanic ashes must be rich in iron and spread ashes to oceanic regions that have a limited concentration of iron. The eruption needs to occur in summer and spring for the phytoplankton to receive enough sunlight for their growth and stimulate the growth of zooplankton and small fishes, which are the food that promotes salmon glut.