Sociable

Tuesday, March 8, 2011

Series of Strong Earthquakes off of Oregan

Earthquake swarm at Clear Lake volcano, CA


earthquakes off of the Oregon coast.


Map Centered at 42°N, 125°W

Right now, there is a series of moderate to strong earthquakes off the coast of Oregon. They are still going on, and within the last couple of hours, a couple more have happened. I don't know what to make of this swarm of large quakes. The area where this is going on is indeed prone to strong quakes and swarms. On a large scale, this is an area where a oceanic tectonic plate is sinking under a continental plate, and there is a spreading zone is to the west of this. Eventually that rifting zone will too be swallowed up by the subduction, and the geology of Oregon and Washington may will resemble that of present day Southern California over millions of years.

California's geology reflects an old subduction zone that melted deep down in the hot mantle, causing the numerous plutons that eventually became the great granite ranges such as the Sierras. The subduction zone ended with the swallowing up of a mid-oceanic ridge at the west end of the plate that was subducted. That swallowed rift zone kicked off the split off of Baja California from mainland Mexico, and created the Sea of Cortez. That spreading zone activity extends up into the Salton Trough today, and many feel that the split will extend up the eastern side of California, splitting California from Mainland USA. This could happen in about 10 million years. A narrow sea will make up Eastern California then.

All this may sound pretty complicated, but I will bring in illustrations of this in due time.

This is that California rifting that I am passionate about!

On another note, the swarm of micro-quakes continues at the Clear Lake volcano, just north of Santa Rosa. CA. There are many small events in just the last 24 hours.

Also, there is a very large volcanic eruption going on on the Big Island, in Hawaii. It had just started today, and is the largest for quite some time.

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