Filters: Tags: {"type":"Theme","name":"volcanology"} (X) > Contacts: {oldPartyId:60405} (X)
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The catastrophic, explosive eruption of Mount St. Helens, Washington, on May 18, 1980, is the most well-known eruption of the volcano. Less well known is the May 18th eruption marked the beginning of a period of eruptive activity that lasted through 1986. From October 1980 through October 1986, a series of 17 dome-building episodes added millions of cubic meters of lava to the crater floor. Most of the growth occurred when magma extruded onto the surface of the dome, forming short (650 to 1,300 feet), thick (65 to 130 feet) lava flows. This data release is a 1-meter resolution digital elevation model (DEM) and a corresponding hillshade raster derived from a previously unpublished 1:2,000 scale topographic contour...
This geologic map database is a reproduction of U.S. Geological Survey Miscellaneous Investigations Map I–2362: “Geologic Map and Structure Sections of the Clear Lake Volcanics, Northern California” (Hearn, Donnelly-Nolan, and Goff, 1995). The database consists of a geologic map, three structural cross sections and a table of petrographic data for each map unit by mineral type, abundance, and size. The Clear Lake Volcanics are in the California Coast Ranges about 150 km north of San Francisco. This Quaternary volcanic field has erupted intermittently since 2.1 million years ago. This volcanic field is considered a high-threat volcanic system (Ewert and others, 2005). The adjacent Geysers geothermal field, the largest...
The catastrophic, explosive eruption of Mount St. Helens, Washington, on May 18, 1980, is the most well-known eruption of the volcano. Less well known is the May 18th eruption marked the beginning of a period of eruptive activity that lasted through 1986. From October 1980 through October 1986, a series of 17 dome-building episodes added millions of cubic meters of lava to the crater floor. Most of the growth occurred when magma extruded onto the surface of the dome, forming short (650 to 1,300 feet), thick (65 to 130 feet) lava flows. This data release is a 2-meter resolution digital elevation model (DEM) and hillshade raster derived from a previously unpublished 1:4,000 scale topographic contour map, based on...
There are 161 active volcanoes in the U.S. and its territories. These volcanoes pose differing degrees of risk to people and infrastructure because of differences in their eruptive styles and geographic locations. This layer shows the areas near volcanic vents that could be affected by proximal volcano hazards, including ballistics (airborne rocks from explosions), pyroclastic density currents, lava flows, debris avalanches, lahars (mudflows), and heavy ashfall, as well as areas downstream that could be affected by distal lahars (see the USGS Volcano Hazards Program Glossary for descriptions of these processes: https://www.usgs.gov/glossary/volcano-hazards-program-glossary). These areas are labelled with their corresponding...
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