by Jack Lee
Most recent update 1530 hours 17 Mar 2010: 8 hours ago a 3.7 hits near Lake Almanor in Northern California.
Previous update at: 2105 hrs. 16 Mar 2010
Are you concerned about the recent number of earthquakes? Los Angeles reported a 4.4 shaker about 14 hours ago and 3 days earlier there was a 4.2 east of El Cahon, near LA. There was 6.7 offshore quake that rattled Chile again and yesterday we had 4.6 off the coast of Oregon. Alaska has been the epicenter of eight earthquakes in the last two days and all of them were over 3 on the Richter Scale – but they have went mostly unreported. But today near Rampart, Alaska they just had a 4. Yellowstone had 11 minor quakes in just the last 4 days. Yellowstone also has volcanic activity. On 3/10 and 3/15 same area had two 3.0 tremblers, the strongest in Northern California in the last 6 days.
Now it has been reported that less than 2 hours 19 minutes ago just off shore in Northern California we had a 4.2 and there were 11 smaller ones around .05 to 1 close to The Geysers about 23 miles from Santa Rose, Ca. The small shakes indicate we are in a state of geologic change and the earth is making adjustments and thats normal. What is not normal is increasing activity in California in cluster quakes. Something is happening, but does this mean the big SF quake is near? Who knows, we just don’t have that kind of predicting ability, but we’re getting better at guessing. The San Andreas fault is probably the best indicator for quakes in California. The fault 1100 kilometers long and it’s been the site of many quakes over the last 150 years.
Basically the San Andreas is the boundary between the North American and Pacific lithospheric plates. Geologists divide it into several segments, each with distinct behavior. A research project has drilled a deep hole into the fault to study the rock there and listen for earthquake signals. This fault is on the move, but how much movement will it take before we have a snap and a major quake?
According to Seismologist Robert M. Nadeau and graduate student Aurlie Guilhem of UC Berkeley, “The tremor activity remains about twice as high today as before the San Simeon quake, while periodic peaks of activity have emerged that started to repeat about every 50 days and are now repeating about every 100-110 days.
What’s surprising is that the activity has not gone down to its old level. The continued activity is worrisome because of the history of major quakes along this segment of the fault, and the long-ago Fort Tejon quake, which ruptured southward from Monarch Peak along 350 kilometers (220 miles) of the San Andreas Fault.”
Haiti, Japan, China, Indonesia, Iran…a whole lotta of shaking going on. But, where’s the big one going to hit next?