The entire west coast of South America has been rocking and rolling with quite a few earthquakes this last two weeks. One of the many volcanoes in Columbia, South America, has begun to erupt. Some of the bigger earthquakes this week have been near the same longitude as this volcano. More earthquakes are rattling the region of volcano Mt. Redoubt.
|15-FEB-2009 10:04:51||-5.84||-80.88||6.2||35.6||NEAR COAST OF NORTHERN PERU|
|14-FEB-2009 05:24:58||-5.81||-80.85||4.7||39.9||NEAR COAST OF NORTHERN PERU|
|09-FEB-2009 14:09:06||-6.47||-80.86||6.1||35.0||NEAR COAST OF NORTHERN PERU|
|08-FEB-2009 21:23:14||-6.63||-80.84||5.1||35.0||NEAR COAST OF NORTHERN PERU|
The entire west coast of South America is releasing stresses and at the bottom of the volcanic chain of this continent, Mt. Chaiten has destroyed the local towns which will not be rebuilt. So now, volcanos at the upper end are now going off, too. The tremendous Boxing Day quake was the second largest yet. This epic event was only 5 years ago. The rest of the planet is still feeling the after effects. All other parts of the planet must readjust themselves to the new status quo caused by the shifts along the entire length of Sumatra Island.
A volcano in southwestern Colombia has erupted, blanketing the nearby provincial capital of Pasto in ash and prompting the evacuation of 7,000 people living in its shadow. There were no reports of damage or injuries.
Galeras, a stratovolcano with a large breached caldera located immediately west of the city of Pasto, is one of Colombia’s most frequently active volcanoes. The dominantly andesitic Galeras volcanic complex has been active for more than 1 million years, and two major caldera collapse eruptions took place during the late Pleistocene. Long-term extensive hydrothermal alteration has affected the volcano. This has contributed to large-scale edifice collapse that has occurred on at least three occasions, producing debris avalanches that swept to the west and left a large horseshoe-shaped caldera inside which the modern cone has been constructed. Major explosive eruptions since the mid Holocene have produced widespread tephra deposits and pyroclastic flows that swept all but the southern flanks. A central cone slightly lower than the caldera rim has been the site of numerous small-to-moderate historical eruptions since the time of the Spanish conquistadors.
If we look at the satellite photo where I circled the volcano in red, right to the east of this behemoth is the town of Pasto, the capital of this state within the country of Columbia. Pasto:
City of the South Colombian West, with a population superior to the 400000 inhabitants and capital of the department of Nariño. Pasto is one of the oldest cities of Colombia, located in the Atriz Valley, in the middle of the Mountain range of the Andes in the Naked denominated mountainous bulk of the Pasto on the foot of Galeras volcano.
About half a million people live near this dragon of a volcano. This is not uncommon at all. Volcanoes are creative forces that attract both plants and animals to their bounteous organic wealth. So far, this particular volcano has not been vicious. But any of these major volcanoes can change from small, unremarkable eruptions into very destructive events and to this day, scientists struggle to figure out, how to tell if this is a possible event.
Many cultures dwelling with restive and violent volcanoes develop fatalistic philosophies. Japan is a stellar example of this. Some try placating the volcanic gods. This particular volcano has had ‘human sacrifices’ in the recent past. Below is a scientific paper describing a new way of looking ‘into’ a volcano:
6 THREE-DIMENSIONAL SPATIAL DISTRIBUTION OF
SCATTERERS IN GALERAS VOLCANO, SOUTH-
6.2.1 GEOLOGICAL HISTORY
Galeras has been erupting lavas and pyroclastic flows during the last million years. Two
major caldera-forming eruptions have occurred, the first about 560,000 years ago in an
eruption which expelled about 15 cubic kilometres of material, and the second some
time between 40,000 and 150,000 years ago, in a smaller but still sizable eruption of 2
km³ of material. Subsequently, part of the caldera wall has collapsed, probably due to
instabilities caused by hydrothermal activity, and later eruptions have built up a smaller
cone inside the now horseshoe-shaped caldera.
Figure 6-2. Galeras volcano from the west flank. Photo by Norm Banks of USGS .
At least six large eruptions have occurred in the last 5000 years, most recently in
1886, and there have been at least 20 small to medium sized eruptions since the 1500s.
Galeras had become active in 1988 after 40 years of dormancy. In 1993, the
volcano erupted when several volcanologists were inside the crater taking
measurements. The scientists had been visiting Pasto for a conference related to the
volcano’s designation as a Decade Volcano. Six were killed, together with three tourists
on the rim of the crater. The eruptive period lasted until 1995. Since then, the volcano
has been in a relative calm stage with some ash and gas emission episodes and low-level
eruptive activity (a crater located to the east of the main one was re-activated in 2002
after more than 10 years of inactivity) dusting nearby villages and towns with ash. A
new eruptive episode began in 2004 (three explosive events have occurred in this
period) and it continues active at the time of this writing (the activity reports are
available at http://www.volcano.si.edu/).
Studying volcanoes is a very dangerous profession. After a few decades of sleeping, the Dragons in volcanoes can awaken quite suddenly. Sometimes, they toss and turn and heave and hiss before attacking. This study is an important thing because being able to predict the behavior of volcanoes is very important for all humanity, not just those who live within direct striking distance. Aside from dangers from volcanic plumes to air flight, many major cities lie in the laps of these monster mountains.
Below is a diagram of this volcano, based on this study:
The presence of this hypothetical reservoir is also supported by petrologic and
seismic data  which indicate that the reservoir is located at a depth of 4-5 km, The
reservoir is able to supply SO2 and other gasses to the upper, more open and fractured
reaches of the volcano through a complex conduit system. Strong degassing fumaroles
are surface expressions of this upper conduit system. As the reservoir cools becomes
less convective and the result is a progressive decline in SO2 fluxes from the volcano.
Then, the reservoir becomes isolated: the reservoir is no longer feed with fresh magma
from deeper regions. During a reactivation cycle, the reservoir is initially supplied with
mafic, sulphur rich magma from a deeper level after a repose period of tens of years.
This supply of magma could be the result of tectonic disturbances nearby. Once this
occurs, the magma can degas from the upper reservoir through the shallow conduit
system and eventually rise to erupt explosively or effusively.
The pictures below show this hot reservoir of magma below volcano Galeras. The black triangle at the top of the two pictures represents the location of this volcano vis a vis this large magma blob:
I wish I could give credit for this study! But the link didn’t give any information. This sort of 3D study of the subterranean structure of all volcanoes should be done! This is definitely something all governments should fund. Just like the entire planet benefits from the army of astronomers, professional and amateur, who scan the heavens. Both volcanoes and meteorites as well as comets are a great hazard to all of us, near and far.
The single most important international cooperative efforts should be in these two areas: tracking the heavens and keeping an eye on hell, below. At the top of the earth, Alaska is also feeling the effects of tectonic plate movement:
This happened today, as I was preparing this story. This latest quake is very close to a volcano that is showing increasing signs, it might belch a bit of volcanic dust. This is a very dirty volcano, prone to dusting everyone nearby, thoroughly. Earthquake rattles Alaska’s largest city :
Jan 24, 2009
A moderate 5.7-magnitude earthquake shook Anchorage, Alaska’s largest city, on Saturday morning.
|15-FEB-2009 19:34:59||61.61||-146.35||4.6||24.4||SOUTHERN ALASKA|
|10-FEB-2009 02:11:21||57.41||-154.56||4.4||35.7||KODIAK ISLAND REGION|
|05-FEB-2009 15:49:29||56.86||-156.31||4.1||70.0||ALASKA PENINSULA|
The latitude of Anchorage is 61.218N. The longitude is -149.9W. Below is a recent photo with identifying elements put together by the fine team of geologists working for United States Geological Survey (USGS), the Geophysical Institute of the University of Alaska Fairbanks (UAFGI), and the State of Alaska Division of Geological and Geophysical Surveys.
The web page run by this consortium of scientists is quite wonderful and I have it bookmarked. The Volcano Hazards Program is the main page of the USGS people. Most of the volcanoes in the lower 48 states erupt a lot less frequently than the Alaskan volcanoes. But some of the worst volcanoes are actually in the lower 48 states. Here is the Yellowstone Volcano Observatory main page.
It is obvious from this bar graph, the eastern end of the volcanic chain is very disturbed. Anchorage must stay on alert so long as the micro quakes and the more violent shakes, continue. Especially since Anchorage is less than 200′ above sea level. My house sits over 200 feet above the town of Berlin, for example, and it isn’t very much higher.
P.O. BOX 483
BERLIN, NY 12022
Make checks out to ‘Elaine Supkis’