Friday, November 11, 2011

Sierraville CA Earthquake Swarm/Dike Intrusion Continues

Sierraville, CA resumed its magma dike intrusion tremors this week, with several quakes recorded today alone. The largest quake, a mag 2.3 tremor, was recorded at a depth of 18mi underground, much shallower than the earlier swarm which suggest magma is in fact on the rise as scientists have said. The dike intrusion started about two months ago, and has so far caused no major damage. The picture below shows the locations of the quakes.

The area of the activity is the same area as the previous activity that I pointed out in an earlier post. This is consistent with dike intrusion and slow uplift of magma toward the surface. The quakes started at a depth of about 30M, and now are at around 18M, so this is significant in that magma dike quakes are getting shallower. It is anyone's guess as to what will happen if the quakes get yet more shallow.

Signs of an impending eruption could include tree kill (as was the case in the 1990's at Mammoth Mountain) which is a result of CO2 being rapidly released along with sulfuric gasses, hot springs showing an elevation in temperature/phreatic eruption, or even a full blown fissure eruption. Given the speed that these quakes are moving upward, and the duration of the dike intrusion, I would assume that there are very powerful pressures working the magma up and would not rule out the possibility of a new volcanic feature in the area.

Keep your eyes peeled on Sierraville, and if you live there, stay vigilant.

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