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INTRODUCTION LASL-80-42 October 1980 Vol~m.:tQ~Qgy at the Los Alamos Scientific Laboratory 1980 Grant Heiken On May 18, 1980. when Mount St. Helens erupted, the American public awoke to the reality of volcanic phenomena. The turbulent clouds, molten rock, and acrid smells of a volcanic eruption are indeed awesome. To the scientist, too, a volcanic eruption is an awesome spectacle, but a volcano, whether active or inactive, is a fascinating natural laboratory. The location, age, and. distinctive features of volcanic f1elds provide clues to the activity going on beneath the Earth's crust. Erupted lavas, volcanic ejecta, and gases provide information on the composition and processes of our planet's interior. Within the United States during the last 150 years, volcanoes have erupted in Alaska, Hawaii, California, ~11~ most recendy in Washington. Volcanic. hazards are multiple. Populated areas. near volcanoes may be endangered by explosive a~tivity and. lava flows. The fallout of volcanic ash may ruin water supplies, crops, viliages, and cities. At greater distances, gases may severely corrode machinery and vehicles and can endanger health. Volcanic gas and ash entering the atmosphere may diffuse across large areas and may lower atmospheric temperatures. Short-term climatic changes caused by volcanic eruptions have shortened growing seasons and produced famine in the Northern Hemisphere. On the positive side, young volcanoes overlie great reservoirs of heat energy that can be used for heating and generating electricity. Ash falls, in moderate amounts, enrich the soils around volcanoes. In many tropical countries, they are necessary for renewal of the soil and continued agricultural u::e of the land. We must understand volcanoes, their causes, and their activity before we can develop them as, sources of heat .or avoid their hazards. VOLCANIC HAZARD ANALYSIS University of California 'L\S\. LOS ALAMOS SCIENTIFIC LABORATORY Posl Office Box 1663 Los Alamos. New Mex•co 87545 505·1667-5061 UNtTC:D STAT£'5 DIEII'AATMENT 0~ £NE.ftGY CONT ... ACT W•J.OS·IENG.·:l5 Permission to reproduce this article is granted. Located on the edge of a geologically young volcanic field, the Los Alamos Scientific Laboratory (LASL) is involved in many aspects of volcanology, particularly as applied to energy, mineral resources, and volcanic hazards. There are several other young volcanic centers in the Southwest where future volcanic activity is possible. At present, volcanic activity in the Southwest is less violent than in the Pacific Northwest. However, even this relatively "quiet" volcanic activity is a significant factor in determining the suitability of a nuclear waste disposal not stop underground, but moved to the surface where it exploded violently. Currently, LASL scientists are studying Mount St. Helens and plan to increase their involvement there. CLIMATIC EFFECTS OF VOLCANIC TIONS Dissected cinder cone and lava flow at Crater Flat, Nevada. This volcano erupted 1.1 mil'lion years ago;" other volcanoes in the region are being studied to determine the potential hazard to proposed nuclear waste repositories at the DeJhlrtment of Energy's Nevada Test Site. site proposed for the Department of Energy's Nevada Test Site. The site is nearly ideal because it is dry and remote. LASL scientists David Vaniman and coworkers are assessing the possibility of volcanic act1ivity near the site and the chemical and physical history of recent volcanism in the area. Previous work on other volcanoes by LASL scientists has provided basic information on phreatic (steam) volcanic eruptions. Through the use of eruption ph()tOgraphs, analyses of the volcanic ash, andi geophysical measurements, phreatic eruptions were studied at Mount Baker, Washington (1975) and La Soufriere de Guadeloupe, French West Indies (1976). At Guadeloupe, LASL scientists were part of an international team studying the volcano's behavior to determine if the activity was a forerunner of more energetic, highly dangerous eruptions. In both areas, the explosive release of steam was generated by ground water coming into ' contact with hot rock beneath the volcanoes. The "volcanic ash" from these two eruptions consisted only.. of rock particles torn from the vent by esc:aping steam. We discovered that the volcanic ash did not contain any fresh glass particles, which normally indicate the presence of molten rock within the erupted material. The lack of erupted molten material influenced the dc:cision to end the evacuation of 80 000 Guadeloupe :residents. At Mount St. Helens, the early phases of activity were phreatic; however, unlike the eruptions at La Soufriere de Guadeloupe and Mount Baker, the molten rock did ERUP- Although the relationship between large volcanic eruptions and short-term climatic changes has been documented. we lack sufficient data to understand the changes. The cooperative research now being done by volcanologists, atmospheric chemists, and meteorologists at LASL and their counterparts in other government agencies will increase our understanding of the growth, dispersion, and composition of volcanic plumes in the Earth's stratosphere. Key elements of the research include observing volcanic plumes with satellites and Iidar (light detection and ranging) and sampling their contents by high-altitude aircraft. The aircraft sampling missions flown for LASL after major eruptions of Soufriere of St. Vincent, British West Indies, in 1979 and Mount St. Helens in 1980 and the follow-up work at LASL and other laboratories will provide us with Scanning electron micrograph of volcanic ash from Mount St. Helens shows a filter sample collected 2 days after the eruption from a stratospheric plume over western Kansas at an elevation of 15.2 km (50 000 ft). The particles consist of volcanic glass, 1 flm to 11Jlm in diameter (400 to 40 millionths of an inch). , u3 Scale, km masses of molt~g, or Pllr.tly .rnolten rock that are located a few kilometers to several tens of kilometers deep. These heat reservoirs provide the energy for the highest grade geothermal resources available to us in the United States. Some of the larger hot rock masses may have volumes of: hundreds to thousands of cubic kilometers and can take up to 2 millicm ~~s to cool to the ambient temperature of the Earth's crust if they are not reheated by the intrusion of new magma. Each m~;~.ss holds an enormous amount of thermal energy. A small amount of this energy is transferred to the surface during the interaction with ground water to produce geysers, hot springs, and natural steam fields, but most of the heat remains locked into the rock, cooled very slowly by conduction into the surrounding area. In its Hot _Dry Rock Geothermal Project, LASL is experimenting with manmade geothermal systems designed to extract this heat for direc~~ _or for the generation of electricity. At an experimental site near Computer plot showing the shock in air and the ash from an eruption of steam-saturated molten intrusion. The velocity of the expanding gas and volcanic ash cloud as it leaves the vent is 125 m/s (279 mph). information on particle concentrations; compositions, and distributions in the plumes and will make these volcanic eruption plumes the best studied in history. The study of volcanic plumes, which are natural examples of the massive injection of particulates into the atmosphere, helps scientists determine if increased production of energy from fossil fuels will harm the Earth's ~£timate through particulate pollution. In addition to climatic-effects applications, the data on eruption plumes will be applied to studies of hazards to aircraft that might pass through them. In a cooperative study with the Smithsonian Institution, the LASL computer facility is being used to construct numerical models of large volcanic blasts like the 1883 eruption of Krakatoa in Indonesia and the recent eruption of Mount St. Helens. The models are used to determine the nature and extent of atmospheric shock waves and the nature of outflow and fallout of ejecta. -YOUNG VOLCANIC FIELDS AS HEAT SOURCES Volcanology can also contribute to the se:arch for alternative energy sources. Young volcanoes overlie The Jemez Mountains in northern New Mexico are composed of volcanic rocks, which have erupted over the last 10 million years; some are as young ' feature in this as 50,000 years. The large circular spacecraft image is the 22 km (14 mi) diameter Valles Caldera, a volcanic collapse feature. Associated with this caldera is a geothermal anomaly; within the anomaly, the natural hot water is being developed by a local utility company and heat is being extracted from impermeable portions by the LASL Hot Dry Rock Geothermal Project. I Los Alamos, t\YQ..dc;Cp wells in natural hot dry rock are connected with a manmade hydraulic fracture. Water is circulated through the loop; where the temperatures are as high as 200°~~ (3,?2°F), to produce hot water and steam. Because the highest grade geothermal resources are associated with volcanic fields, work at LASL is directed at understanding the "plumbing" below these fields, its role as a heat squrce, and its relation to surface features such as volcanic vents and large volcanic collapse features. Through this work, we hope to understand the 'nature and magnitude of the hot dry rock geothermal resource at each of the many young volcanic fields within the United States. VOLCANIC ASH DEPOSITS AND NUCLEAR WASTE ISOLATION LASL research on the present physical and .mineralogical properties of these volcanic deposits, formed during explosive eruptions nearly 15 million years ago, may provide acceptable locations for tht: storage of nuclear wastes. Of interest are old, thick volcanic. ash deposits located in isolated parts of the western United States. LASL scientists are studying deposits in Nevada that consisted of glassy, silica-rich volcanic ash particles that were transformed into zeolites and other minerals during interaction with circulating ground water. Zeolite minerals have internal crystal structures <:onsisting of open frameworks that allow them to be used commercially to filter radionuclides from contaminated effluents. The zeolite-rich, thick volcanic ash deposits would thus act as a natur!l barrier against radionuclide migration from a nuclear-waste repository. BASIC RESEARCH Basic research by geologists at LASL on the origins of volcanism an~ the association of volcanoes with major structural features of the North American continent. has long-term applications. The J~~~.!olcanic lineament of Arizona and New Mexico and the Rio Grande rift of Chihuahua, Texas, New Mexico, and Colorado are the subjects of several LASL studies. The relations of the volcanoes and volcanic fields to these structural features and the changes in composition and distribution of volcanic rocks along them provide clues to their origin and to the distribution of geothermal anomalies and ore bodies associated with these major structural lineaments. THE FUTURE Voh.:anQlqgy is an actively growing science and there is much to be learned. We must accumulate data on phenomena preceding eruJ)tions to develop the capability for prediction, and to understand and cope with the potential hazards to man. We also must increase our understanding of the beneficial aspects. For example, the eruption of Mount St. Helens caused tragedy .for many people, but it also pointed out that within t~~.Cascade Range is a large geothermal resource to be developed. Volcanic danger and volcanic benefits both require long-term research commitments if our studies are to be productive. Mini-Review readerscare encouraged to correspond directly with the author. I