Filters: Tags: volcanic activity (X) > partyWithName: Joel E Robinson (X)
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Medicine Lake volcano (MLV) is a very large shield-shaped volcano located in northern California where it forms part of the southern Cascade Range of volcanoes. It has erupted hundreds of times during its half-million-year history, including nine times during the past 5,200 years, most recently 950 years ago. This record represents one of the highest eruptive frequencies among Cascade volcanoes and includes a wide variety of different types of lava flows and at least two explosive eruptions that produced widespread fallout. Compared to those of a typical Cascade stratovolcano, eruptive vents at MLV are widely distributed, extending 55 km north-south and 40 km east-west. The total area covered by MLV lavas is >2,000...
This report evaluates the volcano-related hazards, including regional mafic lava flows, silicic lava domes, pyroclastic flows, lahars, and volcanic ash, of the Lassen region, California, which is here defined as an area between the Pit River on the north and the southern limit of active Cascade volcanism, approximately 5–10 km south of the southern boundary of Lassen Volcanic National Park. Most active volcanism occurs in a zone about 40 km wide between Viola on the west and the eastern boundary of Caribou Wilderness Area, but sparser volcanism in the west extends the width of this zone to about 75 km. All vents and deposits known or estimated to be less than 100,000 years are identified and considered in establishing...
This geodatabase contains all the geologic map information for the Geologic Map of the San Juan caldera cluster, southwestern Colorado and is part of U.S. Geological Survey Geologic Investigations Map Series I-2799. The San Juan Mountains are the largest erosional remnant of a composite volcanic field that covered much of the southern Rocky Mountains in middle Tertiary time. The San Juan field consists mainly of intermediate-composition lavas and breccias, erupted about 35-30 Ma from scattered central volcanoes (Conejos Formation) and overlain by voluminous ash-flow sheets erupted from caldera sources. In the central San Juan Mountains, eruption of at least 8,800 km3 of dacitic-rhyolitic magma as nine major ash...
Categories: Data;
Types: ArcGIS REST Map Service,
ArcGIS Service Definition,
Downloadable,
Map Service;
Tags: Andesite,
Ash-flow tuff,
Basalt,
Central San Juan Caldera Cluster,
Central San Juan Mountains,
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