Volcano heating up in Alaska; 2nd one this month
Tremors were detected at Pavlof Volcano, 625 miles southwest of Anchorage, according to the Alaska Volcano Observatory.
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“Geologist [I'm Climate Change]”
Since: Mar 07
#1 May 15, 2013
About time too.
This volcano (like cleveland) is squeezing in a long subvertical magma filled fracture formed during rebound /long duration mercalli X (r/lx) quake of the 1780s, which produced a bloody great big tsunami @ Sanak island wiping out an Aleut village in historically documented reportage (and several others where no reports came in). 2 quakes in quick succession are listed on the NOAA website.
The r/lx relaxed the crust from E. Unimak to W. Kodiak, and the long fractures at the base of the crust & solid upper mantle now hold the magma squeezing into the Aleutian-Alaskan peninsula volcanoes in that sector. As the vector appears to have been approximately S. the fractures extend into the backarc to the W. and hit the arc @ the E. where the volcanoes happen to be.
Pavlof, Cleveland, Shishaldin and several others squeezing in the long fracture set from the W. have the highest convergence rate to the W. and the slowest @ the E. so the long fracture set eruptions tend to be relatively regular, building up a sharp & quite pretty cone at the volcano on top of the E. part of the fracture which is the least compressed bit.
Nice to see that Pavlof is almost to schedule as far as tectonic convergence goes...
Will keep watching that space.
Shishaldin appears to be somewhat close to the end of an average interval gap @ present, so may show up as a small eruption in the next year or so.
For the record the same 1708s r/lx opened the fracture set that fed the Novarupta eruption (1912), Drained the katmai magma chamber into the open fracture top & also via a parallel fracture fed the adjacent Trident volcano new growth cone.
Most earthquake research in the region appears to focus on recompression quakes in the forearc of this r/lx sector. The volcanoes will (when they shut down) indicate the likely time of the next r/lx in that sector.
dr. G.Pflaker take note... volcanoes are important indicators of M9 & M9+ r/lx events in megathrust bounded subduction zones. Volcanoes however will not predict forearc & arc recompression earthquakes; BUT, a propagating magma filled fracture causing dilation of the deep crust & upper solid mantle is likely to cause a thrust quake in the forearc segment adjacent to a volcano prior to its arrival @ the volcano. This latter effect is relatively common in the late stage of recompression of an arc prior to r/lx and will result in high volume eruptions of gas rich magma as the untapped magma filled fracture finally hits the surface via the volcano. This has happened in Indonesia in historic time, and may have shown up in the late prehistoric 14C record of the Aleutian arc & Alaska peninsula.
Have a nice day: Ag
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