volcanology basics
eklemetti | May 5, 2009The clock is ticking for the new dome growing at Redoubt to collapse. What will happen if/when it does collapse? Good question!
The new dome at Redoubt. Image courtesy of AVO/USGS, taken by Game McGimsey, April 30, 2009.
Most likely, the following will occur:
First, extrusion of lava will cause the dome to over-steepen, precipitating the collapse (although a large seismic event could also trigger collapse as well). An excellent example of this is the spine that grew at Mont Pelee on Martinique in 1902 before the famous eruption that destroyed St. Pierre and killed >30,000 people.
When it…
eklemetti | April 22, 2009
Satellite image of the island of Tenerife with the main vent of the volcano (El Teide) in the central part of the island.
I will be out of town for the next few days, so I thought I'd leave this thread for breaking volcano news that any of you Eruptions readers notice.
However, I couldn't pass up the opportunity to point out some abysmal science journalism before I go. I mean, I shouldn't have been surprised considering this is from the The Sun(UK), but, come on, could you at least put some effort in?
The article in question pertains to the recent controversy about the level of danger people…
eklemetti | April 5, 2009
Ulawun Volcano, Papau New Guinea, one of the "Decade Volcanoes"
There was some discussion earlier about the so-called "Decade Volcanoes", so I thought I'd elaborate a bit on them (doubly so in light of certain other lists.) These volcanoes are defined by IAVCEI - the International Association of Volcanology and the Chemistry of the Earth's Interior - and are part of a program whose aim is
"to direct attention to a small number of selected, active volcanoes world-wide and to encourage the establishment of a range of research and public-awareness activities aimed at enhancing an…
eklemetti | April 2, 2009
Image courtesy of Calvin Hall. Taken 3/28/2009 during an eruption at 10:59 AM3:28 PM.
UPDATE 4/2/2009 at 11 AM Pacific: I'm moving this up from the comments, but Eruptions reader Doug Cole pointed out (and I have no idea how I missed this) that Redoubt has a new webcam! This one is at the DFR seismic station, ~8 miles / 12 km northeast of the volcano. Great views on it today showing the extent of the ash around Redoubt and the steam/ash plume. This view will also be excellent if we get any dome collapse pyroclastic flows (see below).
After a week of explosions and ash fall, Redoubt seems to…
eklemetti | March 30, 2009
Image courtesy of the Southern California Earthquake Center
I have to admit, I've only been perpherially following the earthquake swarm currently going on in Southern California, near the end of one of the strands of the San Andreas fault out below the Salton Sea (see the bottom of the map above). The "Bombay Beach" swarm (as I'll call it ... beats me what most people are calling it) is being closely monitored by the USGS. However, from what I had heard from a friend of mine with a more structure/tectonics background, looked like tectonic quakes with "beachball focal mechanism solutions"…
eklemetti | March 30, 2009
Goma after the 2002 Eruption of Nyiragongo
The activity at Redoubt has captivated a lot of us, but in the grand scheme of things, its eruption are more likely to caused inconvenience and property damage rather than dramatically loss of life (unless something huge and unexpected occurs). However, the same cannot be said if Nyiragongo and/or Nyamuragira (a.k.a. Nyamulagira) in the Congo were to erupt. These volcanoes are close to the city of Goma, a city of nearly 600,000, not including refugees from the fighting in the region. Eruptions of Nyiragongo in 2002 prompted the displacement of 400,…
eklemetti | March 25, 2009
Image courtesy of AVO/USGS. Taken by Cyrus Read
Based on the current levels of seismicity over the past 36 hours, AVO has returned Redoubt to Orange/Watch status from Red/Warning. This doesn't mean that the eruption is over, just that things have settled down a bit. Flights to and from Anchorage have resumed as well. You can read the full statement here, but the take-home messages are:
AVO expects this to be like the 1989-1990 dome-building eruptions, although no new dome magma has been seen yet (mostly thanks to poor weather).
Dome collapse will likely generate pyroclastic flows with…
eklemetti | March 25, 2009Redoubt seems to be setting its pattern for this part of the new eruptive period. There was another small explosion this morning that produced at 15,000 foot / 5,000 meter ash column that moved to the NNW. The seismicity has settled down since the early morning eruption today (3/25) as well.
These types of explosions producing plinian and subplinian eruption clouds that will likely lead to dome building - the same pattern seen at Mt. Saint Helens in 2004-2008 and the previous Redoubt eruptions in 1989-1990. These explosions, producing ash columns that reach tens of thousands feet, will likely…
eklemetti | March 20, 2009
So, as I am apt to do from time to time, I was wandering the interweb and stumbled across the FEMA (Federal Emergency Management Agency) for Kids website. Naturally, I thought, what do they have to say about, oh, I don't know, volcanoes. Well, was I in for a doozy!
FEMA, in its infinite wisdom, has this to say about volcanoes (for kids, mind you):
[A] volcano is a mountain that opens downward to a pool of molten rock below the surface of the earth.
Oh. My. Word ... but wait, there's more!
The ash can cause damage to the lungs of older people, babies and people with respiratory problems.
Yes…
eklemetti | March 19, 2009Mixing volcanoes and oceans seem to always produce exciting results. Whether it is something as simple as the ocean entry of a lava to something as impressive as a new island emerging, formed by volcanic eruption. Back in the 1960s, a previous unknown undersea volcano off the coast of Iceland erupted to form the island of Surtsey. The signs of the impending eruption were captured from start to finish, with Icelandic fisherman noticing "boiling seas", then steam explosions, then ash eruptions and finally volcanic tephra that formed the island itself. This was followed by lava flows and…
eklemetti | February 19, 2009Jonathan Castro has reminded me that I need a refresher on the proper terminology for ash columns related to volcanic eruptions. It is very easy to start mincing words and using them inappropriately - and that is the sort of sloppy reporting and discussion I am trying to avoid.
So, to refresh my (and our) memory on ash clouds and how to classify them, we can go back to one of the indispensable textbooks on volcanology, Cas and Wright's Volcanic Successions. The classification scheme they provide is summarized in the figure above. It shows the heights of various eruption columns and the…