Satellite images suggest the Calbuco ash cloud has reached at least 14km, Dr Anja Schmidt, a researcher in volcanic impacts and hazards at the University of Leeds, tells Carbon Brief. [...]
"Based on eruptions of other Chilean volcanoes [...], huge emissions of sulfur dioxide are not expected, or supported by the satellite data."
The geographical position of Calbuco may also restrict any global impact, Schmidt says:
"Global climate impacts are also unlikely due to the southern latitude of the eruption, but if the sulphur dioxide mass emission rate were to increase this eruption may temporarily enhance the aerosol particle concentrations in the upper troposphere and lower stratosphere."
The lava fountain reached heights of close to a mile.
A total of 130 earthquakes of magnitude 0.6 to 3.6 have occurred...
...The first, a magnitude 3.5, struck Sept. 13 about 17 miles northeast of West Yellowstone, Mont. Then, in the early hours Sept. 15, two quakes, a magnitude 3.2 and magnitude 3.4, were detected in quick succession at 5:10 and 5:11 a.m., about 15 miles southeast of West Yellowstone. The magnitude 3.6 that marked the peak of the swarm struck nearby about 4 1/2 hours later.
"They weren't big earthquakes," Smith said, "but they were felt."
About half a dozen earthquakes are felt in Yellowstone in an average year, he said.
"This is pretty unusual, to be honest," Smith said...
Aug 29 (Reuters) - Two unusually large earthquakes hit one of Iceland's biggest volcanoes early on Monday, raising concerns of a possible eruption, the Icelandic Met Office said.
The Katla volcano has not erupted properly since 1918 and scientists say it is overdue to do so, although an eruption could still be decades away.
"It is quite a dynamic situation now, in the next hours and days following this, but as we speak at the moment we do not see any signs that there is an imminent hazardous unrest about to happen," Matthew Roberts, a natural hazards scientist at the Icelandic Met Office, said.
Ash from an eruption of the nearby Eyjafjallajokull volcano in 2010 shut down much of Europe's airspace for six days.
Katla, in southern Iceland, was rocked by quakes of magnitude 4.5 and 4.6 overnight. The volcano sustained similar movements in 2011. These are the largest quakes to hit Katla since 1977, when a 5.1 earthquake was measured there.
Two earthquake swarms occurred in the Katla caldera last night. The first was picked up around 1:30 am and comprised of ten earthquakes, the largest of which was magnitude 2.4. The 4.6 and 4.5 quakes were part of the second earthquake swarm which began at 1:41 am. The area has been mostly quiet since, ruv.is reports.
The volcano is covered by an ice cap, which should, in the event of an eruption, typically contain the lava for around 60 to 90 minutes, giving time to alert the population and international air traffic, Roberts said.
http://strokkur.raunvis.hi.is/~sigrun/KATLA.html
1918 eruption - Katla
Reported last month ...
... The partly ice covered Katla volcanic system has been highly active in the Holocene with at least 21 eruption in the last 1100 years. The last eruption to break through the ice took place in 1918 CE.
The Katla system lies on the Eastern Volcanic Zone and is about 80 km long, consisting of a central volcano rising to 1500 m a.s.l. and an active fissure swarm extending towards northeast. The central volcano is partly covered by up to 700 m thick ice and has a 9x14 km ice-filled caldera.
The characteristic activity is explosive basaltic eruptions at the Katla central volcano with tephra volumes (bulk volume) ranging from 0.02 to over 2 km3, accompanied by glacial floods (jökulhlaups) with maximum discharge of up to 300,000 m3/sec. The largest eruptions are effusive basaltic eruptions on the fissure swarm with lava volumes ≥18 km3. Eruption frequency during the last 1100 years is 1 eruption per 50 years.
Since mid-June, earthquake activity within the caldera of the ice-covered Katla volcano has increased above background levels. More than 100 shallow-seated earthquakes have been detected in Katla caldera since 1 June 2016, which is almost four times the monthly average compared to previous years. Earthquakes occurred mainly in bursts ranging from minutes to hours, often with 20 events or more. The two largest earthquakes since the unrest began occurred on 26 July at 03:42 and 03:50 UTC, respectively, both with a magnitude of Mw3.2.
http://icelandreview.com/news/2016/07/3 ... LA-VOLCANO
Katla, one of Iceland's largest volcanoes, was rocked by two abnormally strong earthquakes Monday morning, raising concerns that the volcano may soon erupt.
The southern-Iceland volcano has not erupted since 1918, and scientists believe that a violent release is long overdue. From AD 930 to 1918, there were twenty large-scale eruptions documented by Katla, generally every 13–95 years.
In the early hours on Monday the area was hit by magnitude 4.5 and 4.6 quakes, similar to movements it experienced in 2011.
Interestingly, the volcano is covered by a large icecap, which would likely delay the eruption for around 60 to 90 minutes, according to Roberts. The delay could give people time to evacuate and assist air traffic control in redirecting aircraft.
The ice cap itself presents hazards, though.
“The other hazard might be a jökulhlaup, or glacial outburst flood."
Cid_Yama wrote:Volcanoes: Coming to New England? William Menke
Some 30 years ago, geophysicists detected a 400-kilometer-wide anomaly under parts of New England and eastern New York, where the mantle is unusually hot. It was assumed to be the remnant of a hot spot that moved on some 130 million years ago. Now, based on new seismic images and signs of helium making its way up to lake beds, Menke says the feature is an active upwelling—hot and shallow enough to create lava. Similar features may underlie other parts of the East Coast.
Friday, Dec. 16, 8 a.m.-12:20 p.m., Moscone South Posters. T51G-3012
At the AGU.
Alfred Tennyson wrote:We are not now that strength which in old days
Moved earth and heaven, that which we are, we are;
One equal temper of heroic hearts,
Made weak by time and fate, but strong in will
To strive, to seek, to find, and not to yield.
Abstract
A swarm of microearthquakes occurred on October 31, 2009 within 5 km of the Sunset Crater, Arizona, volcano. A detailed study of the swarm was warranted because of its location near a young volcanic construct and its proximity to the population center of Flagstaff, Arizona. The question posed in this study was whether the swarm was the result of tectonic stress release during fault slip, or due to stresses driven by magmatic processes. This question was addressed by analyzing and comparing the physical and seismic characteristics of the swarm to the regional tectonic environment and to the characteristics of tectonic swarms in Arizona and magmatic/volcanic swarms elsewhere. This analysis included swarm duration, frequency of events, b-value, focal depths and epicentral pattern of the swarm. The comparison of the salient features of the 2009 Sunset Crater swarm to both magmatic and tectonic swarms indicates that the Sunset Crater swarm has features similar to magmatic swarms and is a potential magmatic swarm candidate.
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