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From: Richard Wunderman <WUNDERMA@xxxxxx>
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Chaitén
Southern Chile
42.833S, 72.646W; summit elev. 1,122 m
All times are local (= UTC - 4 hours)
Later updates from multiple sources have indicated that the 2
May 2008 eruption at Minchinmávida (Vnum 1508-04) was incorrectly
attributed. The volcano that erupted was an adjacent caldera, Chaiten
(1508-041). A Volcanic Ash Advisory stated that ash rose to altitudes
in the range of 45,000-55,000 feet [13.7-16.7 km].
Chaiten lies slightly to the W of Minchinmavida. Chaiten
volcano lacks any known modern eruptions but a radiocarbon date on its
tephra (CHA1) yields a date of 7,430 BC (plus or minus 75 years).
Since my message this morning much news (in Spanish and
English) has emerged about today's eruption at Chaiten, correcting the
earlier confusion regarding the name and including numerous photos of
impressive plumes. One report said 1,500 people were evacuated in
Chile. What follows after the Geologic Summary are relevant portions
of reports by others. My thanks to this listserve's Kimberly Genareau
and these other contributors.
Geologic Summary. Chaitén is a small, glacier-free
late-Pleistocene caldera with a Holocene lava dome located 10 km NE of
the town of Chaitén on the Gulf of Corcovado. The north side of the
rhyolitic, 962-m-high obsidian lava dome occupying the 3.5-km-wide
caldera is unvegetated. Obsidian cobbles from this dome found in the
Blanco River are the source of prehistorical artifacts from
archaeological sites along the Pacific coast as far as 400 km away
from the volcano to the north and south. The caldera is breached on
the SW side by a river that drains to the bay of Chaitén, and the high
point on its southern rim reaches 1,122 m. Two small lakes occupy the
caldera floor on the west and north sides of the lava dome. Moreno
(1985 pers. comm.) noted that the nearby volcano of Yelcho listed by
the International Association of Volcanology and Chemistry of the
Earth's Interior (1973) does not exist.
GVP data at http://www.volcano.si.edu/world/volcano.cfm?vnum=1508-041
Rick Wunderman
Global Volcanism Pgm., Smithsonian Inst., wunderma@xxxxxx
--------------------
From: "Flia Villarosa Outes" <gvillarosa@xxxxxxxxxxxxx>
Subject: RE: Sudden Eruption at Minchinmávida Volcano, Chile Last news
from Chilean authorities confirm that the eruption corresponds to
Chaiten, a Pleistocene caldera with only one known eruption during the
Holocene.
Ashes already affected Esquel, Cholila, and Trevelin towns in Argentina.
Gustavo Villarosa
Grupo de Estudios Ambientales GEA
INIBIOMA, CONICET - Universidad Nacional del Comahue CRUB Quintral
1250 8400 Bariloche - Río Negro
(+54 2944) 428505 INT 405
gustavov@xxxxxxxxxxxxxxxxxx
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From: Simon Carn (University of Maryland, Baltimore Campus; and the
Joint Center for Earth Systems Techn.)
SO2 and ash emissions from the eruption reported at
Minchinmávida have been observed in near real-time (NRT) data from the
Ozone Monitoring Instrument (OMI) on NASA's Aura satellite. OMI data
from 18:15UT on May 2 show SO2 clouds extending north as far as
Villarrica, and east over southern Argentina. The OMI Aerosol Index
(sensitive to volcanic ash) suggests the presence of an ash cloud in a
similar location. Preliminary calculations of SO2 burden, assuming a
cloud altitude of ~17 km, yield a total SO2 mass of ~6000 tons.
NRT OMI SO2 data are posted on the following website developed by
NOAA/NESDIS: http://gp16.ssd.nesdis.noaa.gov/pub/OMI/OMISO2/index.html
I note that the source of these emissions remains unclear - the Buenos
Aires VAAC and several newspapers are reporting Chaitén as the source.
A photo appears on this website: http://www.latercera.cl/
contenido/25_9036_9.shtml
Best regards,
Simon
[ simon carn | joint center for earth systems technology ] [ umbc |
1000 hilltop circle | baltimore | md 21250 | usa ] [ 410-455-1454 |
410-455-5868 (fax) ] [ www.volcarno.com | so2.umbc.edu ]
--------------------------------
From: John Ewert (USGS)
[Translation and summary of] Official statement on Chaiten from SERNAGEOMIN
SERNAGEOMIN has the volcano monitoring responsibility in Chile.
http://www.sernageomin.cl/
Statement says that they are going to install two seismic stations.
They say that they registered the seismicity from a station located
near Las Juntas in the south to Choshuenco volcano in the north.
Today's activity is described as pulsing or cycles of explosions.
JE, US Geological Survey, Cascades Volcano Observatory
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