Copyright Information: All images are in the public domain and available for free. If you use this image, credit NOAA/NGDC, C.A. Neal, U.S. Geological Survey. |
Juvenile (new magma) material within the pyroclastic flow deposits consists of these brown, cauliflower-shaped cobble and boulder-sized clasts. The chemical composition of most of the newly erupted material is that of basaltic andesite with a SiO2 content of about 57%, a rock type typical for Crater Peak. Under the microscope, these rocks are only slightly vesicular and contain the minerals plagioclase, pyroxene, and hornblende in a micro-crystalline matrix with very little glass. Also ejected in smaller quantities were fragments, up to several meters across, of old volcanic material from the edifice of Crater Peak, smaller pieces of deeper-seated plutonic and metamorphic rock and partially melted and remobilized basement rock. Image Credit: C.A. Neal. U.S. Geological Survey Photo Date: September 3, 1992 June 27, 1992 Mount Spurr USA volcano Following 39 years of inactivity, Crater Peak vent on the south flank of Mount Spurr volcano burst into eruption at 7:04 a.m. Alaska daylight time (ADT) on June 27, 1992. The Municipality of Anchorage reported nearly $2 million in damage, office closures, and cleanup costs from the August eruption. In addition, there were numerous, small-scale losses incurred by businesses. No loss of life resulted directly from the eruptions. However, two heart attacks, one fatal, from shoveling ashfall were reported in Anchorage. Event Data:
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