Today we had a small magnitude, M = 3.5, earthquake near Point Arena. Based upon the location and focal mechanism, I interpret this to have been a north-northwest striking right-lateral (dextral) strike-slip earthquake. The fault that ruptured is likely either…
Earthquake in the Solomons!
While I was away from the office, we had a M 6.7 earthquake near the Solomon Islands. Here is a link to the USGS website for the M = 6.7 and M = 6.0 earthquakes. While the epicenter plots near…
Andaman Sea Earthquake!
Today we had a small earthquake in the Andaman Sea, west of Thailand and east of the Andaman Isles (India). The Andaman Sea is a region of backarc spreading and connects the Sumatra fault (a (strike-slip) sliver fault that accommodates…
Mid Atlantic Ridge Earthquake!
Yesterday (I was busy preparing revisions to a paper that was due, the 5th 18 hr day in a row) there was a large earthquake along a fracture zone (transform plate boundary) near the Mid Atlantic ridge (MAR). Here is…
Los Angeles: Newport Inglewood Earthquake!
Last night, we had another earthquake on the Newport Inglewood fault (NIF) system. This fault ruptured in 1933, which led to Long Beach adopting the most strict building codes in the nation. Later, these codes were adopted by the state,…
Blanco Fracture Zone: 2000 – 2015 Seismicity Animation
I put together an animation that includes the seismicity from 1/1/2000 until 6/1/2015 for the region near the Blanco fracture zone, with earthquake magnitudes greater than or equal to M = 5.0. The map here shows all these epicenters, with…
Blanco Fracture Zone Earthquakes!
This morning we had three earthquakes related to the Blanco fracture zone, a transform (shear) plate boundary. These earthquakes occurred quite a bit north of the bathymetric expression of the BFZ (though the M 5.8 is actually plotting closer to…
Historic Seismicity Animations: Izu-Bonin, Mariana: 1940 – 2015
Following up on the seismicity in the western Pacific, I put together a couple animations. My post about the deep mainshock (magnitude M = 7.8 ) is here. My second post has some aftershocks plotted (and some foreshocks), as well…
Mid Atlantic Ridge Plate Boundary
In the past week, there have been a few earthquakes along the Mid Atlantic Ridge (MAR) and some associated fracture zones. The Mid Atlantic Ridge is a divergent plate boundary. As the plates move apart, the asthenosphere is decompressed and…
Santa Cruz (western Pacific) Earthquake Swarm!
The past couple of days have brought us a series of large magnitude strike-slip earthquakes along a plate boundary between the Solomon Trench and the New Hebrides Trench. I posted about the first earthquake here and here. This swarm of…