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Rocks ejected during explosive event at summit Mauna Loa Volcano, Hawai'i |
Photograph by D.A. Swanson on March 15, 2000
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An under-appreciated and poorly understood aspect of Mauna
Loa's eruptive activity is the presence of explosion debris on
the east and west sides of the summit caldera. The blocks
shown in the photos were ejected sometime during or after the
caldera formed, less than 1,300 years ago. The largest blocks
are more than 1.5 m in diameter. Most consist of pieces of
old lava flows, but some blocks on the west side are coarse
grained (gabbro is the official rock name) and probably came
from intrusions that cooled slowly enough for minerals to grow
large. The blocks were hot when hurled from the caldera, as
can be determined by the pattern of cooling cracks within
the blocks.
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Photograph by D.A. Swanson on March 15, 2000
Photograph by D.A. Swanson on March 15, 2000
     
The URL of this page is http://hvo.wr.usgs.gov/archive/spotlight_images/20000315-10041_DAS.html/
Contact: hvowebmaster@usgs.gov
Updated: 10 Apr 2000
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