We just had a small earthquake in Redding, California. The shaking was felt as far as 40 km from the epicenter, which was not deep (so probably in the North America plate). The focal mechanism shows that this was a…
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…
Gorda earthquake triggered a Gorda earthquake?
We just had an earthquake along the nodal plane of the Gorda plate earthquake earlier today. Here is the USGS web page for the Gorda M = 4.3 earthquake and here is the USGS web page for the Gorda plate…
Gorda plate earthquake: 2010 zone strikes again
Early this morning we had a small rumbler offshore of northern California, generally in the same location as the 2010.01.10 earthquake. I remember the 2010 earthquake very well as the ground shaking lasted over 20 seconds in Manila. Here is…
Mendocino fault Earthquake
This sure looks like an earthquake on the Transform Plate Boundary fault system known as the Mendocino fault. I have plotted the moment tensor for this earthquake. The shaking intensity contours are plotted. Here is the USGS web page for…
Blanco fracture zone strikes again
The Blanco fracture zone (BFZ) is a transform plate boundary that connects the Juan de Fuca ridge with the Gorda rise spreading centers. This active fault zone consists of numerous right-lateral (dextral) faults. There is some debate as to how…
Mendocino fault earthquake
We had a small magnitude earthquake “today” along the Mendocino fault system approximately 150 km west of Cape Mendocino. Here is the USGS web page for the Mw 4.8 earthquake. Based upon the tectonic setting, the hypocentral depth, and the…
Gorda plate earthquake 2015.02.24
Where else would we get a focal mechanism or moment tensor for an earthquake of such a small magnitude! We are so lucky. This is the USGS web page for the earthquake. We get Gorda plate earthquakes frequently and most…
Stress Changes from Strike Slip Faults
One may ask what are the relations between the Mendocino fault (MF) and the Cascadia subduction zone (CSZ). Earthquakes on both fault systems are responding to the same plate motions. As the Gorda plate moves to the east, relative to…