Mt St. Helens Eruption

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Topic: Sciences
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Introduction

The life of human beings has for a long time witnessed occurrences and impacts of different types of disasters. Natural disasters constitute part of many disasters that are likely to occur in the world. In addition, natural disasters are ultimate effect of natural hazards such as flood, tornado, hurricane, volcanic eruption, earthquakes, and landslide (Hyndman and Hyndman, 1).

When natural disasters occur, they results into diverse negative economic, social, physical and psychological impacts to the people and societies affected either directly or indirectly. Volcano eruptions are categorized as part of natural disasters that are likely to affect human beings.

When they occur, volcanic eruptions are likely to results into widespread negative consequences such as rampant destructions of vegetations and infrastructures, displacement of people, death of people and other animal species, and many other negative consequences (Hyndman and Hyndman, 2).

Mt St. Helens is one of the remaining active stratovolcano mountains in the world, specifically found in United States of America (Meister 20). It is located between Washington and Oregon, in the Cascade Range, where it is part of Cascade Volcanic Arc, and the youngest mountain of Cascade Mountains (Geological Survey-USA 3).

Cascade Volcanic Arc constitutes part of 160 active volcanoes that make up ‘Pacific Ring of Fire’. Mt St. Helens has reclaimed place in the history as far as natural disasters resulting from volcanic eruptions are concerned. The interest of this paper is to look at the Mt St. Helens within the perspectives of natural disaster realms evaluating its history and widespread impacts, together with resilience strategies that have been adopted over time.

History of Mt St. Helens

In trying to understand the genesis of eruption of Mt St. Helens, it is important to locate and describe the historical geographical location of the mountain. Mt St. Helen is estimated to be 2950 meters in height, and as it was seen earlier, it is located in the sparsely populated Cascade Mountains in north-west USA (Meister 20).

Before the famous 1980 eruption of the mountain, it had been established that the mountain had been inactive for about 123 years, a situation that had convinced majority of people in the area that nothing like an eruption could occur in the area (Payne and Jennings 102).

The eruption itself that year was one of the worst eruptions in the country and around the world in a period of 60 years. Mt St. Helens is described as a subduction zone volcano, and this means that the mountain is located on a tectonic plate’s boundary and not necessarily on a hotspot.

Furthermore, description and reaction of tectonic plates shows that, tectonic plates normally move due to convection currents in the earth’s liquid layers (Gray and Schunn 455). In most instances, plates lying below the mountain normally push together or converge, a situation that leads to subduction (Gray and Schunn 455).

Moreover, when the process of subduction occurs, which involves one tectonic plate sliding over the other, solid mantle from the bottom plate are forced down to areas that have high temperatures. As a result, the mantle, which is totally solid in nature, is able to burn and melt in the high temperatures transforming the solid mantle into a viscous liquid magma (Meister 20).

The process of Mt St. Helen’s eruption is described below. Prior and subsequent eruptions history of the mountain has been investigated and narrated by many authors. Here, it has been found that, numerous eruptions took place on the mountain before the main eruption of 1980. Such eruptions have been found to occur when the Juan de Fuca, which is an oceanic crust, moves eastwards towards the North American Plate, which is a continental crust.

The process results in a situation where the continental crust is forced to submerge or move downwards. This process largely constitutes movement, whereby, friction is created that produces earthquake, and since the process is characterized by increase in temperature, the oceanic crust is automatically destroyed. The result of the process was the build-up of magma beneath the mountain, and as pressure increased, the magma forced its way into the earth’s surface.

The formed viscous magma builds up, and this situation is responsible for the increase in the pressure on the earth’s surface. However, since the pressure is not released immediately but waits until the magma shifts, an eruption takes place (Gray and Schunn 455). It has been found out that, volcanic eruption takes place only when the magma rises to the earth’s surface.

Mt St. Helens has been described by geologists as a composite volcano (stratovolcano), which is a term given to steep-sided and symmetrical cones, usually made of alternating layers of lava flows, ash, and related volcanic debris (MountStHelens.com Information Resource Center 1).

One thing that has been observed with the composite volcanoes is that, they normally erupt with great force, a situation that sometimes becomes violent. Due to this, composite volcanoes result into great negative and serious impacts on lives and properties around the mountains (Mt. St. Helens 1).

Before the 1980 eruption, Mt St. Helens had a snowcap and was symmetrical in shape, which led to many people around the mountain referring it as ‘Fujiyama of America’ (History – Mt. St. Helens 1). This nickname may have come about due to the fact that the mountain is part of active Cascade volcanoes, which form part of the circum-Pacific ‘Ring of Fire’, and this zone in the larger American and world history is known to be a dangerous zone characterized by frequent and destructive earthquake activities and volcano eruptions (Furgang 5).

Mt St. Helens got its name from George Vancouver In 1792, a British Royal Navy office and also an enthusiastic explorer. The name St. Helens was in honor of George’s countryman, known as Alleyne Fitzherbert, who was the holder of the title ‘St. Helens’ and at the time, was the British Ambassador to Spain. Separately, locals of the area referred to the mountain as ‘Louwala-Clough’ or ‘the smoking mountain’, probably due to frequent ‘smokes’ of volcanoes from the mountain (Furgang 5).

The eruption of Mt St. Helen did not take place for the first time in 1980, but some credible accounts reveal how the mountain had been experiencing small eruptions for ages. For instance, accounts are made of local inhabitants of the region who were Indians, together with early settlers who came and settled in the region, of how they witnessed less frequent violent outbursts of the mountain (History – Mt. St. Helens 1).

Moreover, other historical evidences advance the notion that, during the mid-19th century, Mt St. Helen was an active volcano mountain for about 26 years between the period 1831 and 1857. Subsequently, the mountain was still active during the three decades prior to the 1831 period, although the nature and extent of the eruption of the mountain was not severe, except for 1800 when there was a major eruption of the mountain (History – Mt. St. Helens 1).

Since 1898 when the mountain was characterized with some forms of eruptions, no thought ever crossed people’s minds that it could reach a time when the mountain could become so violent and so destructive – the way it did in 1980. There was actually no evidence, and even people in the area had settled peacefully in the adjacent lands.

In fact, before the volcano eruption of 1980, Mt St. Helen was regarded and considered one of the serene, quiet, peaceful, and beautiful mountains that had attracted a high number of wildlife, and many people had settled in the region. Moreover, the region was live for tourism activities, since the area had numerous recreational and leisure activities and sites.

Besides all these, at the base of Mt St. Helen, there was Spirit Lake, which had fresh waters, its shores had numerous, and beautiful woods, and this made the lake to become a popular tourism and recreational area for activities such as hiking, camping, fishing, swimming, and boating.

1980 eruption of Mt St. Helen

The following is an account of events that were witnessed prior to the occurrence of Mt St. Helen eruption in 1980. The signs for the eruption of the mountain became evident during the spring of 1980, which actually was in March (Kranz 8). Appropriate date that been accounted in books of history point to 20 March of 1980 as a day when minor earthquakes measuring about 4.1 on the Richter scale was realized (Waugh 266).

In the next few days, the region experienced a number of minor tremors, which continued to take place until 27 March of the year when for the first time, a small eruption of steam and ash was seen coming out of the mountain. These things continued for a number of days, a scenario that became strange to many people, and many tourists were attracted to the mountain.

From March to late April, people in the region were just subjected to instances of tremor and ash coming from the mountain. However, in early May, people found it perplexing when the north side of the mountain began bulging by about 1.5 meters a day, which was a direct indication of how there was build-up of magma and increase of pressure in the mountain.

In early hours of 18 May 1980, an earthquake, which measured about 5.0 on the Richter scale, was experienced in the region, and the earthquake led to the already formed bulge to move forward and downward. This rhythmic forward and downward movement resulted into release of materials, which later formed landslide of rock, glacier ice, and soil (Waugh 266). These materials found their way down to Spirit Lake, leading to displacement.

Due to displacement, materials from the mountain aided by waters from the lake moved in a faster speed to the northern fork of Toutle Valley. On the other hand, the mudflow, which was part of this material movement, moved and found its way to Baker Camp, while floodwater continued down the valley where sediment blocked the port of Portland on the Columba River (Waugh 266).

Almost 20 minutes after these events took place, at about 0833 hours on the same day (18 May), the already exposed magma exploded on its sideways, precipitating a huge blast of waves of volcanic gas, steam, and dust. These found way to the north side of the mountain about 25 kilometers, where all animals and vegetations within this range were totally and completely destroyed (Waugh 266).

In the subsequent hours of the morning after these blasts, there was a series of eruptions, ejecting gases together with ash and volcanic rocks from the mountain, creating magma vents. A thick ash, which formed an invisible cloud, went up about 20 kilometers and drifted to the east of the mountain, where it moved before settling in the Yakima region, which is located 120 kilometers away from the mountain.

This led to an immediate precaution on the people of the region being taken, and people advised to stay indoors and only come out of houses when in facemasks.

Furthermore, three days after the eruption, the volcanic cloud, which had formed in the sky and composed of fine ash, reached the east cost USA. In addition, after several days, it was established that the ash had moved across the world and almost the entire sky of the world was full of volcanic plumes. Estimates from the eruption activities of 18 May 1980 show that the volume of all materials ejected from the mountain was about 2.79 km cubic (Munsart 26).

Further, the eruption was responsible for the removal of the north side of the mountain, and this resulted into a reduction of the height of the mountain by about 400 meters. At the same time, it created a wide crater with an in-depth height of about 800 meters. There was also the opening of the north end, which resulted in creation of a huge breach. By the time the eruption was over, a lot of damage had been done in terms of destruction and loss of lives, as it will be discussed in subsequent paragraphs.

The impact of 1980 eruption of Mt St. Helen

The eruption of Mt St. Helen resulted into many negative consequences that had not been witnessed for a long time in the regions near the mountain and even as far as parts of Alberta Canada. Death of people and animals occurred, together with destructions of vegetations, fish species, and destruction of infrastructures.

It has been noted by numerous authors that the events resulting from the 1980 eruption on St. Helens caused a succession of interacting biological, geological, hydrologic and anthropogenic changes in the surroundings and neighborhoods of Mt. St. Helens (Dale, Swanson and Crisafulli 27). The initial events of the eruption are responsible for the change of landforms, watershed hydrology, availability, and delivery of sediments and the disturbance caused on the vegetations and animals in regulating physical and biological processes (Dale, Swanson, and Crisafulli 27).

At the same time, it has been noted that hydrologic and geomorphic processes were responsible for the change in the paths and rates of ecological responses, which saw habitats change; here, some species were favored, while others were destroyed (Dale, Swanson, and Crisafulli 27).

The first effect of the eruption was on the mountain itself, whereby, geological estimates shows that St. Helens reduced by about 390 meters to its current height of 2560 meters (Waugh 267). Moreover, a huge and wide crater was formed on the mountain, and estimated figures show that the crater measures 3 kilometers long and 0.5 kilometers deep (Bao 186). The created crater is found on the north-facing slope of the mountain.

Moreover, it has been noted that, during the eruption, valleys that surround the mountain were glaciated, a situation that has continued in the region leading to fluvial activities and erosion related activities, which have largely led to erosion in the valleys, giving way to creation and exposure of new landforms. In addition, the next to be affected in the eruption was the drainage system of the region, which changed, and in subsequent years, became dangerous and destructive to the surrounding communities and people.

There are notable three primary rivers in the region covered by Mt St. Helen, which are Toutle River, the Kalama River, and Lewis River. The three Rivers create the Cowlitz River Basin, which was a great and celebrated recreational area before eruption. It should be noted that, the eruption of the mountain was responsible for the production and spread of huge debris and avalanche, and at same time, mudflows and lahars, storm flows, and tephra deposits became common characteristics of the eruption.

The debris avalanche resulted into greater deposition taking place in the Spirit Lake, and the deposition has been estimated to be about 45 to 180 meters deep. Due to this deposition, there was formation of new drainage system on top of avalanche, since major ponds and lakes in the region were breached. This changed the course of many tributaries and water flow patterns, a pattern that has persisted for a long time in the region.

Other features resulting from the change of drainage system of the area include the mudflows and lahars, which also became common features of the eruption. The mudflows developed specifically after the debris avalanche in the South Fork Toutle River and in the tributaries of Lewis River (Lee 75).

Mudflows at the same time caused destruction of the Toutle and Cowlitz Rivers due to high deposition, and this event led to closure of Columbian River for shipping purposes (Lee 77). This came about after the channel capacity of Cowlitz River reduced in size, and this was largely attributed to high levels of deposition.

On the other hand, deposition in the Lewis River and the Swift Reservoir resulted to the rise of water levels in the lake and river by about 0.85 meters. The adverse effect of this increase in water levels was experienced in increased floods in the area, since tributaries of the Lewis River such as Swift Creek, Pine Creek, and Muddy River were affected and they could not find the right course to the river.

Other activities that changed drainage pattern in the area included presence of storm flows due to absence of rivers and vegetations on the riverbanks of major rivers. What this meant was that, during the moments of precipitation and due to lack of friction, water moved fast on the surface of riverbanks, causing aggravated erosion and sedimentation of rivers.

The deposition of sediments in rivers meant that there was reduction in the depth of the river, a situation that became susceptible to increased chances of floods. Furthermore, tephra deposits affected Clearwater River Basin, although the effects of the deposits did not cause adverse effects like the other discussed deposits.

Apart from change in drainage system of the area, other effects of eruption included loss of human life and destruction of numerous settlements, communication, and transport systems. In addition, vegetation and forestry were not spared, while majority of wildlife died. Moreover, farming in the area was disrupted and provision of services was rendered difficult. With regard to loss of lives, it has been estimated that about 57 people perished in the disaster, many were injured, and thousands were left homeless (Lopes and Lopes 127).

It has been observed that, before the eruption took place, there had been promotion of awareness and warnings about the pending disaster, but some people ignored these calls. Some argued from the point that the relative peace and calmness that had been enjoyed in the region could not just end in one day of a disaster to the ‘harmless’ St. Helens mountain (Campbell 1980).

As a result, majority of people not evacuated died, as their homes were buried by the lava of eruption. In addition, people died from burns caused by overwhelming ash, and those who survived to narrate what happened describe the situation to have led to total darkness, high temperatures that resulted into unbearable heat, and suffocating due to lack of oxygen (Fisher, Heiken, and Hulen 8-10).

With regard to infrastructure, historical records indicate that about 123 buildings were destroyed and everything in the Toutle Valley that was upright before eruption was buried in a few hours the eruption took place. Some of the destroyed infrastructure in the valley included bridges, roads, human settlements, electricity supply, and everything that had been developed in the area (Campbell 1980).

Automobiles were affected, as ash from the eruption plugged engines of motors (Noji 190). Subsequently, due to high concentration of volcanic ash in the air, Airports and highways were closed as high volumes of ash fell on farms, towns, forestlands, and all open areas, largely in Washington, Idaho, Montana and the nearby areas (Bryant 247).

Forestry and related vegetations were also not spared, as more destruction took place. For example, when the eruption took place, it was established that every tree located in the 250 kilometer square and lying within the 25 kilometer blast zone, which is to the north of the volcano, was completed destroyed and everything in the name of tree or vegetation was brought to the ground.

Moreover, those trees that were carried away by water caused logjam over a long distance, and in subsequent years, many trees (about 10 millions) had to be re-planted in the region. Apart from vegetation, wildlife was also casualties to the eruption. It has been established that many species of animals, which had attracted tourists in the region and which fell within the blast zone, were completed eliminated.

This also includes fish species, which, majority died due to deposition, sedimentation, and increase in water temperatures and a few managed to hibernate or migrate. On overall, aquatic and marine life of species was destroyed, especially for salmon and trout fish species (Kramer 388).

Conclusion

Mt. St. Helens is one of the Volcano Mountains in the United States of America. Before the mountain erupted in 1980, it was regarded to be a ‘harmless’ mountain, and had become a perfect social, economic, cultural, and physical symbol to the natives of the area and tourist. However, events of May 1980 changed everything, as everybody was shocked by the magnitude of the impact the eruption of the mountain had caused.

The mountain is just one example of the many forms of natural disasters, which cause great effect to the people and other biodiversity. Natural disasters are known to cause death, injuries, and displacement of people, destruction of biodiversity, animal species, and destruction of infrastructures.

The effects become aggravating when the larger population and communities affected by the natural disasters are not fully resilient to such disasters. Therefore, it is important and necessary that mitigation strategies to deal with natural disasters should look into ways of increasing education and awareness among people about the disasters in order to increase their resilience capabilities (Ronan and Johnston 72).

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