Magma stirring under Sierraville, Ca. in ongoing quake swarm

October 19, 2011 –  RENO, NV. – A swarm of more than 700 earthquakes have struck near the small Sierra County, Calif., community of Sierraville since August, although there’s a good chance few if any of the quakes have been felt. There have been more than 30 quakes of a magnitude 1 or more in the last week, the largest being about 1.8, said Ken Smith, seismic network manager for the Nevada Seismological Lab. But the quakes are so deep — most are 18 miles below the surface or more — and so minor Smith thinks they have little chance of being felt at the surface. They are centered about 2 miles west of Sierraville and 31 miles west of Reno. Seismologists can’t say with certainty yet what is happening, but appears the quakes are being caused by moving magma. The earth is basically divided into layers of the crust, the mantle and the core with the temperature getting hotter the deeper the depth. Smith said the ground in this area is constantly in motion, moving about 14 millimeters a year. Because of that motion, it appears magma found a way to flow from the mantle, the middle area, to the crust, the upper area. “The upper mantle in this region has a lot of magma in it,” Smith said. “Sometimes it finds a way to work its way into the lower crust or the crustal-mantle plate. … As everything is moving around, they have an opportunity to inject magma into places where it can.” These quakes appear similar to the swarm of quakes that struck under Lake Tahoe in 2003, which were later determined likely to be deep magma injection, Smith said. This magma — called lava as soon as it reaches the earth’s surface — is not associated with the Lassen Volcano to the north, he said. While it’s not going to end up as a volcanic eruption, it could deform the earth’s crust and set the stage for an earthquake — but not any time soon. A similar swarm occurred in the Sierra region in 2009, but this one is stronger.RGJ
This entry was posted in Earth Changes, Earth Watch, Earthquake Omens?, Seismic tremors. Bookmark the permalink.

3 Responses to Magma stirring under Sierraville, Ca. in ongoing quake swarm

  1. JoshuaNB says:

    “Great earthquakes shall be in diverse places, and famines and pestilences and fearful sights and great signs shall there be from heaven. Nations will rise against nation, but fear not for I am with you ALWAYS.

    Deut.31:6 But be STRONG and of good courage, fear NOT, nor be afraid of anything. For I am the Lord thy GOD, He that is with you always..I will not fail thee, nor forsake thee.. but I am with you always.”


  2. Dennis E. says:

    There has been on going EQ swarms on the Nevada/California border and there has been a remarkable increase in the swarms. Also, if you consistently visit the USGS site, it seems at times the entire perimeter of California seems to be active. Also, at the same time, there has been an increase in EQ swarms in North West Washington State. I am saying something is going to happen, it is just interesting. A whole lot of shaking on going on.


  3. Wow, you get credit for calling this one, 8 days in advance.


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