A discussion of the eruption Mt. Helena in 1980

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A discussion of the eruption Mt. Helena in 1980

Over the past fifteen years substantial developments have been made within high magnitude-low frequency volcanology. It is now becoming increasingly possible to predict an eruption; to understand the processes of eruptions and to develop relevant responses and adjustment programmes (Chester 1993, McCall 1992, White 1972). Yet, regardless of this there are problems. Although science has developed new prediction methods, the accuracy of these is hard to judge, as despite frequent high magnitude-low frequency eruptions during the holocene, they are now relatively rare, thus making adjustment programmes problematic. Volcanologists have however, decided upon two types of programmes (McCall 1992). Firstly, predicting the volcano's future eruptions, carried out through studying past behaviour and secondly, setting up permanent monitoring systems allowing for rapid detection of new seismic activity. General global programmes cannot be augmented however, but, in the aftermath of an eruption the responses and adjustment made can be assessed and can be used as guidelines for future high magnitude-low frequency volcanic areas. The Mount Saint Helens' eruption was one of high magnitude-low frequency and consequently other countries have turned to the responses and adjustments made by Washington State to develop their own programmes.

        This essay will study the responses and adjustments made by Washington State and their effect on programmes developed by Japan, New Zealand, the Philippines and the Indonesian government in relation to Una Una.

        Studies into Mount Saint Helens, situated in the volcanic region of the Cascade Mountains in Washington State, USA, began mainly in the late 1930's by Verhoogan (Geological Survey Prof. Paper 1982). His initial report based on a study of rocks and vegetation, concluded that there had been volcanic activity until recently due to studies revealing the lava to be only a few 100 years old; but it was not until the 1970's interest into Mount Saint Helens increased due to the realisation of its potential hazardousness, prompting The Congress Under the Disaster Relief Aid (1974) to deliver a brief to the United States Geological Survey (USGS) stating their beliefs of a potential eruption and suggesting possible responses and adjustments that could be implemented in the event of the disaster (Chester 1993). In summary, they believed the prime aim was to reduce loss of life, property and natural resources that often takes place as a result of volcano's eruptions and its related consequences, such as land-slides and mud flows.

        As a result of the initial brief, steps were taken based on the suggestions made, to ensure the selected aims would be met. Firstly, the USGS published a hazard map of the area and secondly, they informed the relevant agencies of the warning signs of an eruption and the subsequent guidelines that need to be taken, for example, restricting access to certain areas. As will be seen later these initial steps proved successful.

        In 1975 Dwight Crandell and Donal Mullineaux wrote an article warning of an imminent eruption of Mount Saint Helens within the next 100 years and perhaps even before the end of this century (Geological Survey Prof. Paper 1982). They wrote of the eruptive history of the volcano and produced zoning maps, predicting those areas which would be most effected. Later, Crandell and Mullineaux wrote a further, in depth report (1978) commissioned by the USGS, titled, "Potential Hazards from Future Eruptions of Mount Saint Helens Volcano, Washington" (Chester 1993). Its publication came about as a result of a new research programme investigating the potential hazards in the Cascade Region. From their previous assessments of the area and their subsequent reports they demonstrated that future eruptions will be of high magnitude, producing lava flows, pyroclastic flows, domes, tephra and mud flows - thus becoming hazardous for a multitude of people within the area. This report was widely distributed to the Washington State Governors representatives, Federal and State officials and local agencies in south-west Washington. The Governors representatives misinterpreted the document and thought an eruption was imminent. As a reaction to the report, although at the time being thought of as an overreaction, monitoring and assessment of the volcano commenced (Saarinen and Sell 1985). From the beginning the monitoring process proved problematic as knowledge of past eruptions was relatively sparse, both for Mount Saint Helens or similar Cascade region eruptions as well as for other high magnitude-low frequency eruptions worldwide. Monitoring of the volcano included installing seismometers to detect earthquakes signifying an imminent eruption through monitoring precise ground surface movements and detecting swelling in the volcano.

        Despite this report being credited for the monitoring and assessment systems set up in the volcano's vicinity, the report (referred to as the "Blue Book") nonetheless caused problems amongst many groups including the general public, mainly due to it contradicting the current and accepted perceptions of risk - thus the report can be partly to blame for the misunderstandings that arose (Chester 1993). Two factors contributed to the confusions. Firstly, the last Mount Saint Helens eruption was in 1857 and the last volcanic activity in the Cascade region was between 1914 and 1921, thus the people were reluctant to believe another eruption was imminent. Secondly, those involved in the survey had little experience in predicting the course of volcanoes, thus often information released was inaccurate.

        Although clearly the report bought about confusions, nevertheless, in retrospect, it is possible to see how accurate their predictions were - one of their main pitfalls was that the failed to predict the intensity of the blast. By the beginning of March 1980, when the first signs of earthquakes became apparent, the only instrument monitoring the volcano was a seismometer situated on the western flank. From this instrument the early warning signs were registered and activity gradually increased; further instruments were installed and aerial observations were carried out (Geological Survey Prof. Paper 1982). Again after the small eruption on March 27th, 1980, the programmes and systems were intensified. At all times, officials within the State and the surrounding area were kept well-informed as were agencies and the general public. The United States Forest Service (USFS) lead the news conferences which were broadcast three times a day on both the radio and the television.

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        From studying the monitoring and warning process' carried out before the eruption and from seeing the responses and adjustments made after the eruption, the effectiveness of these initial actions can be measured and from it changes can be implemented for the future. In retrospect, the responses and adjustments taken proved to be both successful and unsuccessful (Chester 1993). Successful aspects include the speed at which the USGS set up monitoring stations and produced and distributed hazard maps after the initial earthquakes in March. Through this rapid process it enabled scientists and volcanologists to verify their opinion of an imminent eruption ...

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