DOCSLIB.ORG

The California Volcano Observatory—Monitoring the State’S Restless Volcanoes

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The California Volcano Observatory—Monitoring the State’S Restless Volcanoes U.S. GEOLOGICAL SURVEY—REDUCING THE RISK FROM VOLCANO HAZARDS The California Volcano Observatory—Monitoring the State’s Restless Volcanoes olcanic eruptions happen in Medicine Lake Vthe State of California about as Mount Shasta Volcano Brushy Butte frequently as the largest earthquakes Twin Buttes on the San Andreas Fault Zone. At Redding Tumble Buttes least 10 eruptions have taken place in Silver Lake Eagle Lake Volcanic Field Volcanic Field California in the past 1,000 years—most Lassen Volcanic recently at Lassen Peak in Lassen Center Volcanic National Park (1914 to 1917) in the northern part of the State—and As a part of the U.S. Geological Clear Lake Survey’s Volcano Hazards future volcanic eruptions are inevitable. Volcanic Field Program, the California Volcano The U.S. Geological Survey California Sacramento Volcano Observatory monitors the Observatory aims to advance scientific understanding of State’s potentially hazardous volcanoes. San Long Valley volcanic processes and lessen Francisco Volcanic Region the harmful impacts of volcanic USGS activity in the volcanically active areas of California. More than 50 volcanoes in the CALIFORNIA Ubehebe Fresno Craters United States have erupted one or VOLCANO OBSERVATORY more times in the past 200 years. The Golden Trout Creek Coso most volcanically active regions are in Volcanic Field Volcanic Hawaii, Alaska, Washington, Oregon, Field and California. California’s volcanoes Volcano threat are dispersed throughout the State—from High to very high Lavic Lake near its northern border with Oregon Moderate Volcanic Field to its southern border with Mexico. Low The U.S. Geological Survey California Los Angeles Volcano Observatory (USGS CalVO) in Erupted within the last 1,000 yrs Menlo Park watches over California’s Salton potentially hazardous volcanoes to help 0 100 200 MILES Buttes communities prepare for, and respond to, San Diego 0 100 200 KILOMETERS volcanic activity. Volcanoes of very high to low threat are scattered throughout California, from the Oregon border Some California Volcanoes are (north) to Mexico (south). Other older volcanoes in California are of less concern. California’s More Hazardous Than Others volcano watch list is subject to change as new data on past eruptive activity are collected, as volcanic unrest changes, and as populations in threatened areas grow or decline. The USGS has ranked the volcanic threat at all U.S. volcanoes using volcano California Volcanoes Erupt in age, types of potential hazards, and This type of low-level volcanic Various Styles and Produce estimates of the societal exposure to unrest can persist for decades or even those hazards. Sixteen volcanoes are hundreds of years without an eruption. Diverse Hazards on California’s watch list to monitor. Although steady, low-level unrest is Explosive eruptions blast lava Research suggests that partially molten normal for many young volcanoes, fragments (tephra) and gas into the air rock (magma) lies beneath seven of these rapidly accelerating unrest is cause for with tremendous force. The finest particles volcanoes—Medicine Lake Volcano, concern. At California’s most threatening (ash) billow upward, forming an eruption Mount Shasta, Lassen Volcanic Center, volcanoes, monitoring sensors are in column that can attain stratospheric Clear Lake Volcanic Field, the Long place to continuously track levels of heights in minutes. Simultaneously, Valley Volcanic Region, Coso Volcanic unrest. Such monitoring is necessary to searing volcanic gas laden with ash and Field, and Salton Buttes. At these determine the baseline, or background coarse chunks of lava may sweep down volcanoes, earthquakes (seismicity), hot level, of activity at a volcano to help the flanks of the volcano as apyroclastic springs, volcanic gas emissions, and (or) volcanologists know what is normal. flow. Ash in the eruption cloud, carried ground movement (deformation) attest to An uptick in unrest may be a sign of by the prevailing winds, is an aviation their restless nature. increased volcanic threat. hazard and may remain suspended for U.S. Department of the Interior Fact Sheet 2014–3120 U.S. Geological Survey December 2014 hundreds of miles before settling to the ground as ash fall. During less energetic effusive eruptions, hot, fluid lava may issue from the volcano as lava flows that can cover many miles in a single day. Alternatively, a Prevailing wind sluggish plug of cooler, partially solidified lava may push up at the vent during an effusive eruption, creating a lava dome. A growing Eruption cloud u p t i o lava dome may become so steep that it E r n collapses, violently releasing pyroclastic flows l u m potentially as hazardous as those produced Tephra c o n during explosive eruptions. During and after an explosive or effusive (ash) eruption, loose volcanic debris on the flanks of the volcano can be mobilized by heavy rainfall fall or melting snow and ice, forming powerful Lava dome floods of mud and rock (lahars) resembling Lava dome collapse Vent P y rivers of wet concrete. These can rush down r o c l valleys and stream channels as one of the most a s t i c destructive types of volcano hazards. w f l flo L o w tic a When a dormant volcano reawakens, las n Pyroc d sl a series of events commonly unfolds—the ide energy of eruptive activity increases, peaks, Lava flow and then gradually subsides as the volcano returns to a state of rest. The 1914 to 1917 Lahar (mud or debris flow) eruptions of Lassen Peak produced a yearlong Magma conduit series of minor steam blasts before a major explosion sent an eruption column 30,000 feet high and unleashed devastating pyroclastic flows and lahars. Windborne ash drifted 275 Volcanoes produce a variety of natural hazards that can damage infrastructure miles eastward and fell as far away as Elko, and negatively affect regional economies. This diagram shows the kinds of Nevada. The climactic phase of the eruption hazards that pose risks at volcanoes in California and elsewhere. Some hazards, was over in a matter of days, but recurring such as lahars and landslides, can occur even when a volcano is not erupting. steam blasts and lahars created hazardous Modified from “Geologic Hazards at Volcanoes” (USGS General Information conditions for several years afterwards. Product 64). Unlike other natural disasters, volcanic eruptions and their associated hazards can persist for months, years, or even decades before an “all clear” can be sounded. High to very high threat volcanoes. Several of California’s young volcanoes are less than 100 miles from major population centers. The inherent beauty of the State’s volcanic regions draws thousands of visitors each year, while their potential for geothermal energy has attracted industrial developers. Medicine Lake Volcano Mount Shasta Lassen Volcanic Center High threat Very high threat Very high threat Lava Beds National Monument, about 30 miles south This 14,162-foot-high volcano holds the Lassen Volcanic National Park, located about of Klamath Falls, Oregon, is located on the lower headwaters of the upper Sacramento 50 miles east of Redding, showcases the northern flank of the shield-shaped Medicine Lake River and is adjacent to several towns and dynamic history of this area and draws more Volcano and contains the highest concentration of major highway, rail, and air transportation than 350,000 visitors each year. Lassen Peak lava-tube caves in North America. corridors. erupted violently in the early twentieth century. The California Volcano Observatory uses several modern instrumental methods to monitor volcanoes. Three key techniques measure earthquakes (seismicity), movement of the ground surface (deformation), and the types and amounts of gases released from a volcano (gas geochemistry). Left: Sophisticated sensors like this Global Positioning System (GPS) receiver and seismometer in the Long Valley Volcanic Region can detect ground deformation and seismicity that occur as magma or volcanic gas rises toward the Earth’s surface in the weeks to months prior to an eruption. Data are telemetered from sensors in the field to USGS offices in Menlo Park, California, for processing and interpretation. Early detection of eruption precursors via a reliable volcano monitoring network is essential to hazard mitigation. Mammoth Mountain, a volcano made up of overlapping lava domes and flows, is visible behind the monitoring equipment. Right: Volcanic-gas “sniffer” at Mammoth Mountain continuously measures temperature plus carbon dioxide and other gas concentrations at a steaming vent. Volcano Hazard Zones Identify Statewide, California’s volcano CalVO Provides Timely Forecasting Threatened Areas. hazard zones encompass more than 24,000 of Volcano Hazards square miles, of which about half is Maps of volcano hazard zones convey privately owned and about half is public The mission of the California Volcano the types of hazards that may occur during a land that is managed by the U.S. Forest Observatory is to enhance public safety and future eruption and the areas of likely impact. Service, National Park Service, or Bureau minimize societal disruption in the event of The specific hazards to people and property of Land Management. Within these zones volcanic unrest through delivery of effective depend on the eruption style (effusive or are natural resources and infrastructure forecasts of volcanic activity derived from explosive), the volume of lava erupted, the essential to California’s water, power, monitoring and rigorous scientific research. location of the vent, the eruption duration, and transportation systems. Although less Whereas USGS maps of volcano hazard and local water-flow and precipitation than 1 percent of California’s population zones provide long-term perspectives on conditions. Low-energy effusive eruptions lives within a designated hazard zone, future volcanic activity, short-term forecasts are destructive, but generally not life more than 20 million recreational visitors give warning of likely outcomes under threatening. High-energy explosive eruptions are attracted annually to the dramatic rapidly changing conditions during volcanic are destructive and life threatening.
Load more

Recommended publications
  • Volcanic Gases and Aerosols Guidelines Introduction
    IVHHN Gas Guidelines www.ivhhn.org/gas/guidelines.html Volcanic Gases and Aerosols Guidelines The following pages contain information relating to the health hazards of gases and aerosols typically emitted during volcanic activity. Each section outlines the properties of the emission; its impacts on health; international guidelines for concentrations; and examples of concentrations and effects in volcanic contexts, including casualties. Before looking at the emissions data, we recommend that you read the general introduction to volcanic gases and aerosols first. A glossary to some of the terms used in the explanations and guidelines is also provided at the end of this document. Introduction An introduction to the aims and purpose of the Gas and Aerosol Guidelines is given here, as well as further information on international guideline levels and the units used in the website. A brief review of safety procedures currently implemented by volcanologists and volcano observatories is also provided. General Introduction Gas and aerosol hazards are associated with all volcanic activity, from diffuse soil gas emissions to 2- plinian eruptions. The volcanic emissions of most concern are SO2, HF, sulphate (SO4 ), CO2, HCl and H2S, although, there are other volcanic volatile species that may have human health implications, including mercury and other metals. Since 1900, there have been at least 62 serious volcanic-gas related incidents. Of these, the gas-outburst at Lake Nyos in 1986 was the most disastrous, causing 1746 deaths, >845 injuries and the evacuation of 4430 people. Other volcanic-gas related incidents have been responsible for more than 280 deaths and 1120 injuries, and contributed to the evacuation or ill health of >53,700 people (Witham, in review).
    [Show full text]
  • Warm Storage for Arc Magmas SEE COMMENTARY
    Warm storage for arc magmas SEE COMMENTARY Mélanie Barbonia,1, Patrick Boehnkea, Axel K. Schmittb, T. Mark Harrisona,1, Phil Shanec, Anne-Sophie Bouvierd, and Lukas Baumgartnerd aDepartment of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA 90095; bInstitute of Earth Sciences, Heidelberg University, 69120 Heidelberg, Germany; cSchool of Environment, The University of Auckland, 1142 Auckland, New Zealand; and dInstitute of Earth Sciences, University of Lausanne, 1015 Lausanne, Switzerland Contributed by T. Mark Harrison, September 28, 2016 (sent for review August 2, 2016; reviewed by George Bergantz and Jonathan Miller) Felsic magmatic systems represent the vast majority of volcanic volumes outweigh their extrusive counterparts is sufficient rea- activity that poses a threat to human life. The tempo and son to assume that both may record different aspects of the magnitude of these eruptions depends on the physical conditions reservoir’s history (15–19); this is because melt-dominated volcanic under which magmas are retained within the crust. Recently the rocks may only represent a volumetrically minor part of the magma case has been made that volcanic reservoirs are rarely molten and reservoir, whereas plutonic rocks represent conditions in the crystal- only capable of eruption for durations as brief as 1,000 years dominated bulk of the magma reservoir (18). To provide a physical following magma recharge. If the “cold storage” model is generally context for our interpretive scheme, we point to simulations of applicable, then geophysical detection of melt beneath volcanoes is Bergantz et al. (19) that show that the full extent of thermal ex- likely a sign of imminent eruption.
    [Show full text]
  • Springs of California
    DEPARTMENT OF THE INTERIOR UNITED STATES GEOLOGICAL SURVEY GEORGE OTIS SMITH, DIBECTOB WATER- SUPPLY PAPER 338 SPRINGS OF CALIFORNIA BY GEKALD A. WARING WASHINGTON GOVERNMENT PRINTING OFFICE 1915 CONTENTS. Page. lntroduction by W. C. Mendenhall ... .. ................................... 5 Physical features of California ...... ....... .. .. ... .. ....... .............. 7 Natural divisions ................... ... .. ........................... 7 Coast Ranges ..................................... ....•.......... _._._ 7 11 ~~:~~::!:: :~~e:_-_-_·.-.·.·: ~::::::::::::::::::::::::::::::::::: ::::: ::: 12 Sierra Nevada .................... .................................... 12 Southeastern desert ......................... ............. .. ..... ... 13 Faults ..... ....... ... ................ ·.. : ..... ................ ..... 14 Natural waters ................................ _.......................... 15 Use of terms "mineral water" and ''pure water" ............... : .·...... 15 ,,uneral analysis of water ................................ .. ... ........ 15 Source and amount of substances in water ................. ............. 17 Degree of concentration of natural waters ........................ ..· .... 21 Properties of mineral waters . ................... ...... _. _.. .. _... _....• 22 Temperature of natural waters ... : ....................... _.. _..... .... : . 24 Classification of mineral waters ............ .......... .. .. _. .. _......... _ 25 Therapeutic value of waters .................................... ... ... 26 Analyses
    [Show full text]
  • Source to Surface Model of Monogenetic Volcanism: a Critical Review
    Downloaded from http://sp.lyellcollection.org/ by guest on September 28, 2021 Source to surface model of monogenetic volcanism: a critical review I. E. M. SMITH1 &K.NE´ METH2* 1School of Environment, University of Auckland, Auckland, New Zealand 2Volcanic Risk Solutions, Massey University, Palmerston North 4442, New Zealand *Correspondence: [email protected] Abstract: Small-scale volcanic systems are the most widespread type of volcanism on Earth and occur in all of the main tectonic settings. Most commonly, these systems erupt basaltic magmas within a wide compositional range from strongly silica undersaturated to saturated and oversatu- rated; less commonly, the spectrum includes more siliceous compositions. Small-scale volcanic systems are commonly monogenetic in the sense that they are represented at the Earth’s surface by fields of small volcanoes, each the product of a temporally restricted eruption of a composition- ally distinct batch of magma, and this is in contrast to polygenetic systems characterized by rela- tively large edifices built by multiple eruptions over longer periods of time involving magmas with diverse origins. Eruption styles of small-scale volcanoes range from pyroclastic to effusive, and are strongly controlled by the relative influence of the characteristics of the magmatic system and the surface environment. Gold Open Access: This article is published under the terms of the CC-BY 3.0 license. Small-scale basaltic magmatic systems characteris- hazards associated with eruptions, and this is tically occur at the Earth’s surface as fields of small particularly true where volcanic fields are in close monogenetic volcanoes. These volcanoes are the proximity to population centres.
    [Show full text]
  • Human Impacts on Geyser Basins
    volume 17 • number 1 • 2009 Human Impacts on Geyser Basins The “Crystal” Salamanders of Yellowstone Presence of White-tailed Jackrabbits Nature Notes: Wolves and Tigers Geyser Basins with no Documented Impacts Valley of Geysers, Umnak (Russia) Island Geyser Basins Impacted by Energy Development Geyser Basins Impacted by Tourism Iceland Iceland Beowawe, ~61 ~27 Nevada ~30 0 Yellowstone ~220 Steamboat Springs, Nevada ~21 0 ~55 El Tatio, Chile North Island, New Zealand North Island, New Zealand Geysers existing in 1950 Geyser basins with documented negative effects of tourism Geysers remaining after geothermal energy development Impacts to geyser basins from human activities. At least half of the major geyser basins of the world have been altered by geothermal energy development or tourism. Courtesy of Steingisser, 2008. Yellowstone in a Global Context N THIS ISSUE of Yellowstone Science, Alethea Steingis- claimed they had been extirpated from the park. As they have ser and Andrew Marcus in “Human Impacts on Geyser since the park’s establishment, jackrabbits continue to persist IBasins” document the global distribution of geysers, their in the park in a small range characterized by arid, lower eleva- destruction at the hands of humans, and the tremendous tion sagebrush-grassland habitats. With so many species in the importance of Yellowstone National Park in preserving these world on the edge of survival, the confirmation of the jackrab- rare and ephemeral features. We hope this article will promote bit’s persistence is welcome. further documentation, research, and protection efforts for The Nature Note continues to consider Yellowstone with geyser basins around the world. Documentation of their exis- a broader perspective.
    [Show full text]
  • Late Holocene Earthquake History of the Imperial and Brawley Faults, Imperial Valley, California
    Late Holocene Earthquake History of the Imperial and Brawley Faults, Imperial Valley, California Aron J. Meltzner and Thomas K. Rockwell Geological Sciences San Diego State University Final Technical Report U.S. Geological Survey Grant No. 02HQGR0008 February, 2004 Table of Contents List of Figures ii Abstract 1 Introduction 4 The Imperial Fault at Harris Road 10 Methodology 14 Trench Stratigraphy 15 Structure and Earthquake History 23 Event Z 23 Event X 23 Event V 24 Event T 24 Discussion 27 Conclusions 30 Acknowledgements 31 References Cited 32 Table 1a and 1b 35 Table 2 36 i LIST OF FIGURES Figure 1. Generalized fault map of the southern part of the Salton Trough. Surface ruptures indicated for the 1892 (M 71/4), 1934 (ML 7.1), 1940 (MW 6.9), 1968 (MW 6.5), 1979 (MW 6.4), and 1987 (MW 6.2 and 6.6) earthquakes. Figure 2. (a) Profiles of right-lateral component of displacement as a function of length along fault for the 1940 and 1979 ruptures. Comparison of slip in the two events shows important similarities and differences. Sieh (1996) argued that this example supports the concept of characteristic slip within individual patches of a fault, but not characteristic earthquakes. He argued that the sharp slip gradients in both 1940 and 1979 a few kilometers north of the international border suggest the presence of a fixed patch boundary. Redrafted from Sharp (1982b). (b) Diagram illustrating the “slip-patch” model as proposed by Sieh (1996) for the Imperial fault: accumulated over scores of earthquake cycles, slip along the fault between stepovers is uniform, and in both stepover regions, slip tapers to zero.
    [Show full text]
  • The Science Behind Volcanoes
    The Science Behind Volcanoes A volcano is an opening, or rupture, in a planet's surface or crust, which allows hot magma, volcanic ash and gases to escape from the magma chamber below the surface. Volcanoes are generally found where tectonic plates are diverging or converging. A mid-oceanic ridge, for example the Mid-Atlantic Ridge, has examples of volcanoes caused by divergent tectonic plates pulling apart; the Pacific Ring of Fire has examples of volcanoes caused by convergent tectonic plates coming together. By contrast, volcanoes are usually not created where two tectonic plates slide past one another. Volcanoes can also form where there is stretching and thinning of the Earth's crust in the interiors of plates, e.g., in the East African Rift, the Wells Gray-Clearwater volcanic field and the Rio Grande Rift in North America. This type of volcanism falls under the umbrella of "Plate hypothesis" volcanism. Volcanism away from plate boundaries has also been explained as mantle plumes. These so- called "hotspots", for example Hawaii, are postulated to arise from upwelling diapirs with magma from the core–mantle boundary, 3,000 km deep in the Earth. Erupting volcanoes can pose many hazards, not only in the immediate vicinity of the eruption. Volcanic ash can be a threat to aircraft, in particular those with jet engines where ash particles can be melted by the high operating temperature. Large eruptions can affect temperature as ash and droplets of sulfuric acid obscure the sun and cool the Earth's lower atmosphere or troposphere; however, they also absorb heat radiated up from the Earth, thereby warming the stratosphere.
    [Show full text]
  • GY 111: Physical Geology
    UNIVERSITY OF SOUTH ALABAMA GY 111: Physical Geology Lecture 9: Extrusive Igneous Rocks Instructor: Dr. Douglas W. Haywick Last Time 1) The chemical composition of the crust 2) Crystallization of molten rock 3) Bowen's Reaction Series Web notes 8 Chemical Composition of the Crust Element Wt% % of atoms Oxygen 46.6 60.5 Silicon 27.7 20.5 Aluminum 8.1 6.2 Iron 5.0 1.9 Calcium 3.6 1.9 Sodium 2.8 2.5 Potassium 2.6 1.8 Magnesium 2.1 1.4 All other elements 1.5 3.3 Crystallization of Magma http://myweb.cwpost.liu.edu/vdivener/notes/igneous.htm Bowen’s Reaction Series Source http://www.ltcconline.net/julian Igneous Rock Composition Source: http://hyperphysics.phy-astr.gsu.edu Composition Formation Dominant Silica content Temperature Minerals Ultramafic Very high Olivine, pyroxene Very low (<45%) Mafic High Olivine, pyroxene, low Ca-plagioclase Intermediate Medium Na-Plagioclase, moderate amphibole, biotite Felsic Medium-low Orthoclase, quartz, high (>65%) muscovite, biotite Igneous Rock Texture Extrusive Rocks (Rapid Cooling; non visible* crystals) Intrusive Rocks (slow cooling; 100 % visible crystals) *with a hand lens Igneous Rock Texture Igneous Rock Texture Today’s Agenda 1) Pyro-what? (air fall volcanic rocks) 2) Felsic and Intermediate Extrusive Rocks 3) Mafic Extrusive Rocks Web notes 9 Pyroclastic Igneous Rocks Pyroclastic Igneous Rocks Pyroclastic: Pyro means “fire”. Clastic means particles; both are of Greek origin. Pyroclastic Igneous Rocks Pyroclastic: Pyro means “fire”. Clastic means particles; both are of Greek origin. Pyroclastic rocks are usually erupted from composite volcanoes (e.g., they are produced via explosive eruptions from viscous, “cool” lavas) Pyroclastic Igneous Rocks Pyroclastic: Pyro means “fire”.
    [Show full text]
  • Deep Carbon Emissions from Volcanoes Michael R
    Reviews in Mineralogy & Geochemistry Vol. 75 pp. 323-354, 2013 11 Copyright © Mineralogical Society of America Deep Carbon Emissions from Volcanoes Michael R. Burton Istituto Nazionale di Geofisica e Vulcanologia Via della Faggiola, 32 56123 Pisa, Italy [email protected] Georgina M. Sawyer Laboratoire Magmas et Volcans, Université Blaise Pascal 5 rue Kessler, 63038 Clermont Ferrand, France and Istituto Nazionale di Geofisica e Vulcanologia Via della Faggiola, 32 56123 Pisa, Italy Domenico Granieri Istituto Nazionale di Geofisica e Vulcanologia Via della Faggiola, 32 56123 Pisa, Italy INTRODUCTION: VOLCANIC CO2 EMISSIONS IN THE GEOLOGICAL CARBON CYCLE Over long periods of time (~Ma), we may consider the oceans, atmosphere and biosphere as a single exospheric reservoir for CO2. The geological carbon cycle describes the inputs to this exosphere from mantle degassing, metamorphism of subducted carbonates and outputs from weathering of aluminosilicate rocks (Walker et al. 1981). A feedback mechanism relates the weathering rate with the amount of CO2 in the atmosphere via the greenhouse effect (e.g., Wang et al. 1976). An increase in atmospheric CO2 concentrations induces higher temperatures, leading to higher rates of weathering, which draw down atmospheric CO2 concentrations (Ber- ner 1991). Atmospheric CO2 concentrations are therefore stabilized over long timescales by this feedback mechanism (Zeebe and Caldeira 2008). This process may have played a role (Feulner et al. 2012) in stabilizing temperatures on Earth while solar radiation steadily increased due to stellar evolution (Bahcall et al. 2001). In this context the role of CO2 degassing from the Earth is clearly fundamental to the stability of the climate, and therefore to life on Earth.
    [Show full text]
  • Identification and Location of Seismic Signals at the Nirano Mud Volcanic
    Geophysical Research Abstracts Vol. 20, EGU2018-17534-1, 2018 EGU General Assembly 2018 © Author(s) 2018. CC Attribution 4.0 license. Identification and location of seismic signals at the Nirano Mud Volcanic Field, Italy Verónica Antunes (1), Thomas Planès (1), Matteo Lupi (1), Aurore Carrier (1), Anne Obermann (2), Adriano Mazzini (3), Tullio Ricci (4), Alessandra Sciarra (4), and Milena Moretti (4) (1) Department of Earth Sciences, University of Geneva, Geneva, Switzerland ([email protected]), (2) ETH Zürich, Erdbebendienst (SED), Zurich, Switzerland, (3) Centre for Earth Evolution and Dynamics (CEED), University of Oslo, Norway, (4) Istituto Nazionale di Geofisica e Vulcanologia (INGV), Rome, Italy Mud volcanoes are geological phenomena characterized by elevated fluid pressures at depth. This phenomena are only recently being investigated with passive seismic methods. To identify and characterize seismic signals produced at the Nirano Mud Volcano, Italy, we deployed a temporary network composed of 11 stations. During the three months survey period, the stations repeatedly recorded high frequency signals. We identi- fied two types of drumbeat signals. The first has duration of about 50s and a frequency range of 10-45 Hz. The second signal has a duration of about 4s and a frequency range of 5-45 Hz. The drumbeat signals are not recorded on all the stations and their amplitude varies according to the detected signal type, suggesting a marked attenuation in the region. We located the source region of the drumbeat signals at the north eastern-most region of the mud volcano system, using cross-correlation methods between station pairs. This observation is in agreement with geological observations: the most active part of the system is at the edge of the caldera where the fault controlled collapse occurs, hence facilitating the rise of deep fluids.
    [Show full text]
  • GEOLOGIC MAP of the MOUNT ADAMS VOLCANIC FIELD, CASCADE RANGE of SOUTHERN WASHINGTON by Wes Hildreth and Judy Fierstein
    U.S. DEPARTMENT OF THE INTERIOR TO ACCOMPANY MAP 1-2460 U.S. GEOLOGICAL SURVEY GEOLOGIC MAP OF THE MOUNT ADAMS VOLCANIC FIELD, CASCADE RANGE OF SOUTHERN WASHINGTON By Wes Hildreth and Judy Fierstein When I climbed Mount Adams {17-18 August 1945] about 1950 m (6400') most of the landscape is mantled I think I found the answer to the question of why men by dense forests and huckleberry thickets. Ten radial stake everything to reach these peaks, yet obtain no glaciers and the summit icecap today cover only about visible reward for their exhaustion... Man's greatest 2.5 percent (16 km2) of the cone, but in latest Pleis­ experience-the one that brings supreme exultation­ tocene time (25-11 ka) as much as 80 percent of Mount is spiritual, not physical. It is the catching of some Adams was under ice. The volcano is drained radially vision of the universe and translating it into a poem by numerous tributaries of the Klickitat, White Salmon, or work of art ... Lewis, and Cis pus Rivers (figs. 1, 2), all of which ulti­ William 0. Douglas mately flow into the Columbia. Most of Mount Adams and a vast area west of it are Of Men and Mountains administered by the U.S. Forest Service, which has long had the dual charge of protecting the Wilderness Area and of providing a network of logging roads almost INTRODUCTION everywhere else. The northeast quadrant of the moun­ One of the dominating peaks of the Pacific North­ tain, however, lies within a part of the Yakima Indian west, Mount Adams, stands astride the Cascade crest, Reservation that is open solely to enrolled members of towering 3 km above the surrounding valleys.
    [Show full text]
  • Insights Into the Recurrent Energetic Eruptions That Drive Awu Among the Deadliest Volcanoes on Earth
    Insights into the recurrent energetic eruptions that drive Awu among the deadliest volcanoes on earth Philipson Bani1, Kristianto2, Syegi Kunrat2, Devy Kamil Syahbana2 5 1- Laboratoire Magmas et Volcans, Université Blaise Pascal - CNRS -IRD, OPGC, Aubière, France. 2- Center for Volcanology and Geological Hazard Mitigation (CVGHM), Jl. Diponegoro No. 57, Bandung, Indonesia Correspondence to: Philipson Bani ([email protected]) 10 Abstract The little known Awu volcano (Sangihe island, Indonesia) is among the deadliest with a cumulative death toll of 11048. In less than 4 centuries, 18 eruptions were recorded, including two VEI-4 and three VEI-3 eruptions with worldwide impacts. The regional geodynamic setting is controlled by a divergent-double-subduction and an arc-arc collision. In that context, the slab stalls in the mantle, undergoes an increase of temperature and becomes prone to 15 melting, a process that sustained the magmatic supply. Awu also has the particularity to host alternatively and simultaneously a lava dome and a crater lake throughout its activity. The lava dome passively erupted through the crater lake and induced strong water evaporation from the crater. A conduit plug associated with this dome emplacement subsequently channeled the gas emission to the crater wall. However, with the lava dome cooling, the high annual rainfall eventually reconstituted the crater lake and created a hazardous situation on Awu. Indeed with a new magma 20 injection, rapid pressure buildup may pulverize the conduit plug and the lava dome, allowing lake water injection and subsequent explosive water-magma interaction. The past vigorous eruptions are likely induced by these phenomena, a possible scenario for the future events.
    [Show full text]