volcanic hazards
eklemetti | March 20, 2009
Now that people have been able to get a better look at the are about Hunga Tonga Hunga Ha'apai, we've been able to get a better idea of what sort of eruption occurred. The explosions and ash/tephra from the eruption have all but wiped out life on Hunga Ha'aapai, as the island contains one of the vents, while the other is only 100 meter off shore of the island - although the tephra erupted so far have joined the new vent and the island. You can clearly see ash mixing with the water around the island and the island itself has been blackened by the coating of ash. This is a classic volcanic…
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 | March 18, 2009
Image from AVO Hut webcam for Redoubt
After an exciting few days ... well, OK ... after an exciting few hours on Sunday, AVO has decided to lower the alert level at Redoubt in Alaska to Yellow/Advisory. The alert level was lowered last week after seismicity at the volcano returned to normal after weeks of rumbling (at Orange/Watch status), but then we are all caught by surprise when a phreatic explosion occurred (and AVO returned the volcano to Orange). However, this didn't lead to a new period of heightened seismicity, so back to Yellow we go (even with elevated gas emissions and a nice…
eklemetti | March 18, 2009
The eruption of Hunga Tonga Hunga Ha'apai volcano in Tonga looks to be a big one. Keleti Mafi, head of the Tongan geological service, calls this "a very significant eruption, on quite a large scale", which is no surprise considering some of the spectacular picture we saw of the eruption yesterday. In fact, the eruption is big enough that it has disrupted air traffic over Tonga, as Air New Zealand has issued a warning about the ash column - an ash column that has reached over 15,000 meters/50,000 feet! Luckily for the residents of Tongatapu, a mere 10 kilometers 50 km to the southwest SSE…
eklemetti | March 17, 2009
Image from keizo/weblog
Hunga Tonga-Hunga Ha'apai (how's that for a name?), a shallow seamount in Tonga, appears to have erupted. An air passenger snapped some pictures of an eruption occurring in the ocean between the Tongatapu and Vava'u and pilots in the area report that (unsurprisingly), the feature is new.
Hunga Tonga-Hunga Ha'apai - at least the part above water (look in the bottom of the image, the islands are marked in green) - is made of two small islands that cap the main seamount and ring the volcano's caldera. The last known eruption from the volcano was in 1988 - over twenty…
eklemetti | March 17, 2009
Now that Redoubt has decided that Yellow/Advisory is not to its likely and has returned to an Orange/Watch status, I'll continue bringing new updates of the volcano has events unfold.
And nothing much has unfolded since the phreatic explosion that occurred on Sunday. The current state of the volcano, according to AVO, is minor seismic unrest and that is about it. They do offer some more details of the events on Sunday:
An AVO overflight Sunday witnessed activity from 11:30 AM until about 3:00 PM and was able to document ash emission from a new vent, just south of the 1990 lava dome and west…
eklemetti | March 16, 2009
Oldonyo L'engai, Tanzania
As with most disasters, the best way to prevent a Katrina-like catastrophe is preparedness. The best successes in volcanic mitigation have been in places where the combination of monitoring, communications and practice fit together like so many legos in a set, allowing for a calm and orderly evacuation when the eruption, or signs of eruption, began (e.g., Rabaul in 1994). This is why it is always heartening to me to see articles about places trying to implement hazard mitigation plans for their volcanoes. Two examples are in the news today:
(1) Officials in…
eklemetti | March 14, 2009I missed this the first time, but Click & Clack from NPR's Car Talk answered a question about how to volcano-proof your car.
If you want to hear it, click here. As usual, the guys in Cambridge (our fair city) do an excellent job with the information and the humor.
{Hat tip to Jen Glass at Arizona State}
eklemetti | March 14, 2009
Photo: The north flank of Mount Redoubt in early February 2009. Credit: Chris Waythomas / Alaska Volcano Observatory/U.S. Geological Survey
I've been following the waxing and waning of activity at Mt. Redoubt in Alaska for the past two months like many of you have. For a time there, the volcano had the nation's attention, both from the threat of a eruption near major shipping and oil hubs and from some questionable comments made by a certain Republican governor. However, nature sometimes doesn't play well with others, so after weeks of the Alaska Volcano Observatory's warnings that the…
eklemetti | March 13, 2009
2009 has been a busy year for Volcan Galeras in Colombia. The volcano has erupted at least twice this year already vigorously enough to prompt evacuations of the area. Galeras does tend to see cycles of eruptive activity, the last one started in 2000 after seven years of quiet. Many times, the eruptions are more visually impressive than hazardous (see the picture above from January 2008 from INGEOMINAS).
Luckily, Galeras is also once of the most watched volcanoes in South America. The INGEOMINAS (Colombian Geological Survey) staffs the Pasto Volcano Observatory (OVSP) to monitor the volcano…
sb admin | March 12, 2009
Welcome to version 2.0 of Eruptions, the blog on volcanic eruptions and volcano research in general. I've been writing this blog (starting over on Wordpress) over the last year or so, but now it has found a new home here at ScienceBlogs. If you're wondering what to expect if you're new to Eruptions, I'll be bringing news of volcanoes that are erupting worldwide, distilling the scientific jargon, dispelling the misinformation and commenting on what the effects of the eruption(s) might be. I'll also try to bring in any volcanoes in the popular media that gets my attention (alas, it has been…
eklemetti | March 10, 2009I am back from the ion microprobe lab at Stanford after a few days of data collection, so I'll be trying to get back on posting schedule here at Eruptions.
UPDATE 3/10/2009 12:45PM: Here is a little (and I mean a little) more information, mostly adding that the local residents have been given a "warning" about the activity.
However, I did notice this morning at Sakurajima in Japan erupted after rumbling over the weekend. There aren't many details about the eruption beyond the fact that volcanic chunks were thrown a few kilometers from the vent, but the BBC does have some nice video of the…
eklemetti | March 3, 2009
Count this as your mini-update for Redoubt, with the news being no news. Even AVO seems a little bored with Redoubt lately (not to say they aren't watching it as vigilantly as ever) as their last three updates have been exactly the same:
Redoubt volcano has not erupted. Seismicity is low, but above background levels and consists mainly of small discrete earthquakes. Night has fallen and no image is visible in the webcam.
However, down the road (arc-wise) in the Aleutians, AVO has raised the alert level at Okmok Caldera. New volcanic tremors were felt yesterday at Okmok, averaging about one…
eklemetti | February 26, 2009The Redoubt watch is now been going for well over a month and this is how quickly things can change when monitoring volcanoes. The headline in my volcano RSS, when I saw it said:
"Redoubt quiets after weeks of activity, though eruption still possible"
By the time I clicked on the link, the headline for the KTUU TV article became:
"Redoubt steaming at strongest level, seismic activity calms"
The seismic event refered to happened yesterday afternoon (Alaska time) and the volcano rumbled for about an hour, getting picked up by seismometers all around the Cook Inlet. They also mention that steam…
eklemetti | February 25, 2009
The people who remain in Chaiten face the potential for a devasting pyroclastic flow, so says Jorge Muñoz of the SERNAGEOMIN in Chile. The volcano is still producing large ash columns on Tuesday and a flyover of the dome forming inside the caldera has lead to the concern that a collapse on a larger scale than those seen last week could wipe out the town for good.
The government hopes news like this from volcanologists might convince the last remaining residents of Chaiten to leave, but no indication of this has come to pass. In fact, things sound like they're getting heated in the fight…
eklemetti | February 23, 2009
I have never had to leave my home in an evacuation from a natural disaster. I'll put that out there right now. So, I might not fully understand the emotions going through people when they find out that they have to leave their home by no fault of their own because nature has decided that where they live is no longer livable. I especially don't know what it might be like if you are then told you can never go back. You might have a home there. You might own a business there. You might have grown up there. Your great grandparents might have lived there over 100 years ago. Yet, you are told -…
eklemetti | February 20, 2009
Galeras, in Colombia, appears to have entered a new cycle of activity as it has erupted for the second time in a week. A large explosion occurred this morning that was accompanied by falling ash and rocks (ballistic bombs) from the event. It is unclear how far the volcanic products travelled from the vent, but Colombian officials did raise the alert level back to red and ordered new evacuations.
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…
eklemetti | February 19, 2009
UPDATE 2/19/2009 9:45 AM: Well, it seems that my hunch was at least partially right. Reuters (and Paula Narvaez, special envoy to the Chilean president) is calling the eruption as result of "what appeared to be a partial collapse of its cone."Â So, we might have seen the oversteepening of the dome growing in the Chaiten caldera that lead to a collapse, producing (likely) a pyroclastic flow and either an accompanying plinian eruption as the pressure was released or an ash column associated with the pyroclastic flow itself. Now, I might not take Reuters word for it, but it makes sense…
eklemetti | February 18, 2009
I found this little press release that doesn't have a huge amount of information, but is interesting nevertheless. The Coordinating Committee for Prediction of Volcanic Eruptions of Japan (nice name) is putting seven volcanoes on "24/7" monitoring. That sounds like we might see a lot of eruptions in Japan soon ... except that their rationale was that these volcanoes "are likely to affect public life by erupting or becoming active in the coming 100 years". That is quite the window of eruptive opportunity! The question is what exactly "24/7" monitoring - does this mean that someone/something…