volcanic hazards
eklemetti | June 9, 2008
Today, I saw a report that a dome on Arenal in Costa Rica had collapsed last Friday (report in Spanish, but good picture of the event), producing a block & ash flow that left a 800-meter scar on the volcano's flank. No one was injured during the avalanche, but tourists were evacuated as a precaution. There have been minor rock fall related to the andesite lava that has been erupting over the last year, but apparently this is the first major avalanche.
This shows the fine line between an effusive (lava flow dominated) eruption and explosive (pyroclastic dominated) eruption. Although this…
eklemetti | June 8, 2008
I mention this little human interest piece mostly because I am especially found of Mt. Tarawera (note: this link goes to the GVP page for Okataina, the volcanic cluster of which Tarawera is a member)Â in New Zealand. This Tuesday (June 10) is the 122nd anniversary of its most recent eruption, the 1886 eruption that erupted the Rotomahana Basalt. The eruption itself was relatively unique as it was a basaltic eruption that was almost entirely dominated by explosive eruptions of basaltic tephra (see illustration above). This likely means that the basalt was highly enriched in volatiles gases…
eklemetti | June 6, 2008
I had been looking for some pictures of the recent eruption of Cerro Azul in the Galapagos, and finally I found some posted on the BBC. There are some rather stunning pictures of the rift eruption (#3), the lava flows heading downslope (over older lava flows, #4) and even a little lava spatter (#1).Â
eklemetti | June 6, 2008
Reuters has a short video showing some of the damage inflicted on Chaiten by the volcano of the same name. Looks like the ash, lahars and flooding have wiped out at least a third of the town (according to the voice-over) ... and in a sense, Chaiten (the town) lucked out as the destruction could have been a lot worse.
eklemetti | June 6, 2008
A few reports this morning that Mt. Soputan, on the island of Sulawesi in Indonesia, is currently erupting. The reports indicate that there has been a lot of seismic activity and some ash emitted from the volcano. As with many volcanoes in the densely populated nation of Indonesia, there are people living on the slopes of Mt. Soputan and the authorities are preparing to evacuate them, if necessary. The last eruption at Soputan was way back in ... 2007 (see photo above), so it seems like the volcano is another one of many active Indonesian volcanoes.
eklemetti | June 3, 2008
I've been trying to find information to post this week, but not much out their in the press this week.
I did like this article on the close relationship between Salvadoran coffee growers and Santa Ana/Ilamatepec Volcano. After being pressed into an emergency lecture yesterday here about the interactions between humans and volcanoes, this is case in point that a mere 3 years after an eruption helped wipe out their crops, coffee growers are back to planting near Santa Ana's crater. It is hard not to when the soils near the volcano are so fertile. You can see in the picture (above) how lush the…
eklemetti | May 30, 2008
I always find it interesting how and why news of a volcanic eruption makes it into the press. Sometimes it is just to report the eruption itself, however, a lot of the time it is more to report the "human interest" side of the story, or in this case, the wildlife side of the story. Cerro Azul, one of the volcanoes in the Galapagos islands, apparently erupted on Thursday (5/29). Lavas flows on the northeast side of the volcano are threatening the Giant Galapagos Tortoises and their status (the tortoises and the lava flows) will be monitored.
On the volcanic side of things, Cerro Azul last…
eklemetti | May 30, 2008
We've been hearing a lot of conflicting reports about the state and future of the Chaiten eruption. Now ending its fourth week of eruption, Chaiten was said to be easing up a bit, but recent reports have Luis Lara from the SERNAGEOMIN still worried about a potential collapse, followed by a devastating eruption. I'll have to take his word for it as the explanations in the article don't really make a lot of sense. It sounds like both Lara and Dr. Petrinovic (Argentina) are worried about dome collapse, but that would just form large pyroclastic flows ... unless the dome collapses enough to…
eklemetti | May 29, 2008
This isn't really new activity, but a report on the ongoing activity at Soufriere Hills on Montserrat in the West Indies. Soufriere Hills is a composite volcano that has been erupting for almost 11 years now, producing pyroclastic flows and ash fall that have wiped out entire towns on the island of Montserrat. Most of the activity is caused by dome collapses, where the viscous dacite lavas will erupt to form domes that then become oversteepened and collapsed due to gravity. This material is still hot (usually) and forms the deadly pyroclastic flows. Sounds like there have been a few dome…
eklemetti | May 28, 2008
Some news from the Chaiten eruption. Apparently, LanChile has cancelled some flights around the region of southern Chile due to the ash. They likely implies that the eruption column is bigger than reported by the SERNAGEOMIN on Monday, but the report has little in the way of details. Sounds like the volcano is still huffing and puffing away. Definitely one of the more important and interesting eruptions in the last few hundred years and it has the Cascades Volcano Observatory along with the USGS VDAP buzzing (based on some conversations I've had recently), even almost four weeks in.
eklemetti | May 26, 2008
I'm always amazed by the number of volcanic eruptions captured by satellites that we might not have ever even had known occurred otherwise. Case in point is Rabaul on the island of New Britain in Papua New Guinea. An Aqua satellite captured this shot of Rabaul erupting on May 20th, leaving a gorgeous plume heading off into the Pacific. Sure, most likely someone might have noticed the eruption, but its good to see that we can find eruptions going on even when we're not really looking.
Rabaul is a caldera volcano that is most famous for the simultaneous eruptions of Vulcan and Tavurvur in 1994…
eklemetti | May 26, 2008
Tungurahua, one of the most active (and harder to pronounce) volcanoes in the Andes, has been experiencing explosions over the last few days. Not much in the report beyond the 125 explosions, increased seismicity and ashfall around the volcano. This is fairly typical behavior of Tungurahua: Strombolian-style eruptions (see the picture above for a great example) with ash and blocks being ejected from the crater. The volcano has been continuously erupting since 1999.
eklemetti | May 26, 2008
People living around Semeru Volcano, Indonesia, have been put on alert for a potential eruption. Indonesia's Centre for Volcanology and Geological Hazard Mitigation has put the volcano on level 3 (of 4) alert and said "not to conduct activity at a radius of 4 kilometres from the crater, especially around the south-east of the volcano's slopes." There have also been reports of ash clouds (or steam) being vented from the crater.
Semeru is a very active volcano in a country full of active volcanoes. It has been erupting since 1967, quite a long span for any stratovolcano to be constantly…
eklemetti | May 26, 2008
I think we know who wins this battle. At Ruapehu (New Zealand), it isn't really the lava that is the problem, but the lahars produced by mixing snow, crater lake water and volcanic debris. However, that is not stopping people from wanting to ski on the volcano. Never ceases to amaze me how people assess the riskiness of activities.
eklemetti | May 17, 2008
Happy 28th anniversary of the 1980 Mt. Saint Helens eruption. The volcano had a catastrophic collapse of one side of the edifice that triggered the climatic eruption. Enjoy this clip from the CBS News from 3 days after the eruption.
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eklemetti | May 16, 2008
The latest eruption at Kilauea has increased the amount of vog on the big island of Hawai'i. Vog is more or less the same as the anthropogenic "smog" produced by car/industrial exhaust, but produced by volcanic gases (carbon dioxide, carbon monoxide, sulfur dioxide, hydrogen sulfide amongst others). It definitely doesn't make for good air quality, especially with the current lack of strong tradewinds in Hawai'i right now.
eklemetti | May 15, 2008
At first it seemed like the new eruptions at Mt. Etna (Italy) were petering out rather quickly. Instead, now it seems that there are fears that a new rift might be opening on Etna, which might mean more vents for lava to erupt. Apparently there has also been some seismic activity to go along with the new eruption and rifting, which shouldn't be too surprising.
It is also noted that Stromboli, another one of the Aeolian volcanoes, is erupting now as well. Busy time for Italian volcanoes!
eklemetti | May 15, 2008
If Chaiten, Llaima and Puyehue weren't enough, the Chilean Regional Emergency Office is placing seismometers on Peteroa volcano after its shown signs of increasing activity. The volcano is located out on the border with Chile and Argentina and has a number of glaciers that start from the edifice. Looking at the eruptive history of Peteroa, it seems that it has spasms every 30 years or so, although the last known eruption was ~10 years ago. The eruptions are mostly phreatic explosions (related to magma-water interaction) and the last known eruption that produced significant lava, ash and…
eklemetti | May 14, 2008
A bit busy today, so to borrow from the newest USGS/SI Volcanism Report:
On 12 May, the plume rose to an altitude of 8 km (26,200 ft) a.s.l.
During an overflight conducted by SERNAGEOMIN, four more plumes of a
similar altitude were generated by explosions and drifted NE. Several
hectares of burned vegetation, likely from pyroclastic flows or
lateral explosions, were noted on the N flank of the dome. Small
pyroclastic flows may also have been responsible for completely burned
forest to areas in the NE, and on the W and NW dome flanks. A lahar
caused the banks of the Chaitén River to overflow…
eklemetti | May 13, 2008
I just read a report that the ash column at Chaiten is beginning to collapse. The SERNAGEOMIN says that the ash column is only 4.5 km tall now, as opposed to the 20 km it had reached earlier. Still, there are not reports of pyroclastic flows, but that could be a matter of hours or days at this point. We'll be keeping a close watch on the eruption to see if this is the beginning of the end, or just a lull in eruptive activity, here a full 12 days into the eruption.
UPDATE 12:20 PM (Pacific Time): According to this new article, the SERNAGEOMIN is reporting the first of the column-collapse…