Earthquake Lube

Back  in September, I predicted a major earthquake on the West Coast.  It still hasn’t happened, although there have been a lot of quakes elsewhere, and in some pretty unlikely places like Central Oklahoma and South-Central Texas. 

I still think we’ll see one in California soon, but I came across an article that might help explain why it hasn’t happened already.  Here’s an excerpt:

Geophysicists from Potsdam have established a mode of action that can explain the irregular distribution of strong earthquakes at the San Andreas Fault in California. As the science magazine Nature reports in its latest issue, the scientists examined the electrical conductivity of the rocks at great depths, which is closely related to the water content within the rocks. From the pattern of electrical conductivity and seismic activity they were able to deduce that rock water acts as a lubricant.

Los Angeles moves toward San Francisco at a pace of about six centimeters per year, because the Pacific plate with Los Angeles is moving northward, parallel to the North American plate which hosts San Francisco. But this is only the average value. In some areas, movement along the fault is almost continuous, while other segments are locked until they shift abruptly several meters against each other releasing energy in strong earthquakes. After the San Francisco earthquake of 1906, the plates had moved by six meters.

The San Andreas Fault acts like a seam of the earth, ranging through the entire crust and reaching into the mantle. Geophysicists from the GFZ German Research Centre for Geosciences have succeeded in imaging this interface to great depths and to establish a connection between processes at depth and events at surface. "When examining the image of the electrical conductivity, it becomes clear that rock water from depths of the upper mantle, i.e. between 20 to 40 km, can penetrate the shallow areas of the creeping section of the fault, while these fluids are detained in other areas beneath an impermeable layer", says Dr. Oliver Ritter of the GFZ. "A sliding of the plates is supported, where fluids can rise."

These results suggest that significant differences exist in the mechanical and material properties along the fault at depth. The so-called tremor signals, for instance, appear to be linked to areas underneath the San Andreas Fault, where fluids are trapped. Tremors are low-frequency vibrations that are not associated with rupture processes as they are typical of normal earthquakes. These observations support the idea that fluids play an important role in the onset of earthquakes.

Source: Helmholtz Association of German Research Centers

Not content to wait around for an earthquake, Los Angeles County has declared a state of emergency today because of Santa Ana winds that have done millions of dollars in damage.  L A Times photos

Winds near 100 mph have wreaked havoc as far east as Utah and Colorado.