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February 10th, 2002
Although it's approaching two decades since the last major volcanic eruption in the contiguous 48 U.S. states,
there are currently two active volcanoes in Mexico.
Popocatépetl Volcano is located just southeast of Mexico City and has been erupting intermittently since 1994.
Further west, Colima's Volcano of Fire has been active since 1998 and has
increased in activity this past week prompting evacuations.
(If your Spanish is rusty try using a babelfish.)
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Popocatépetl Volcano
December 22, 2001 |
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Both of these volcanoes are steep-sided stratovolcanoes.
They form part of a continental volcanic arc where the Cocos Plate subducts northward under the North American Plate.
In each of these volcanoes there is an active lava dome
filling the summit crater. These lavas are intermediate in composition (andesite),
and much more viscous than the mafic lavas (basalts)
that erupted in the Congo last month, and therefore won't flow as easily. However, this
also means that these volcanoes are more prone to violent eruptions that produce
pyroclastic flows and dangerous
eruption clouds. One of the neat
byproducts of the monitoring efforts at these
volcanoes is nifty webcams that allow you to watch eruptions live.
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Colima Volcano
February 5, 2002 |
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You should also check out this month's Geotimes Magazine, published by
the American Geological Institute. This month's issue has stories about
Olympic Earthquake Watchers and
The Geology of Afghanistan. AGI also publishes a
brochure about Careers in the Geosciences.
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February 3rd, 2002
The February 2002 issue of National Geographic Magazine
features an article entitled "Etna Ignites"
about last summer's spectacular eruptions of Mount Etna, Europe's tallest active volcano. Etna is a
massive shield volcano that dominates the eastern half of the island of Sicily in the Mediterranean Sea.
Fissure eruptions
fed lava flows that threatened a
ski area and a scientific observatory on Etna's flank, but stopped short of the populated areas near the
base of the volcano. One unusual aspect of last year's eruption was the vigor of eruption and the presence
of the mineral amphibole in the erupted lava. These new developments may signal a more violent future for
a volcano that has the reputation of being a "friendly giant". The article also includes a nice
oblique map
showing the historical activity of Etna.
A magnitude 6 earthquake struck
central Turkey today. The dozens
of deaths associated with this quake are unusual for a quake of this magnitude, but the region is
certainly no stranger to deadly quakes - in 1999 a pair of magnitude 7 quakes on the North Anatolian Fault
killed many thousands. The North Anatolian Fault is a transform plate boundary, similar to the San Andreas Fault.
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Wednesday, January 12, 2005
