Hi All. I see on the USGS map there was a small quake located on the San Andreas fault near the center of Carrizo Plane. Any other time this would not cause me to take a second look except for what it might represent in the future. This is the first quake in quite a spell to center on the SAF in this area. At present time there is nothing about this quake that would suggest that something larger is in the offering.

Could this the general area of Petra's "deep, dark and ugly?" In a very small way it could, but only a very way, but as everyone knows a snowball starts out small, but grows larger as it picks up more snow. If no more quakes occur this could be nothing more then another small quake. Could it be that "deep, dark and ugly" has already occurred and all this is left is for the mechanics of it to make it known?

Billion Watts has had the feeling about the Fort Tejon area. Could this be nothing more then a name he see but in reality that which he feels so strongly about is further north?

Paleoseismic sites in the Carrizo Plain contain five ruptures during the last 900 years. The geomorphic offsets in the Carrizo Plain were larger than the offsets southeast of Cholame during the 1857 Fort Tejon earthquake. The characteristic earthquake model, a model often used to consider earthquake recurrence, states that ruptures along a particular fault segment recur at similar magnitudes and with similar offsets. If there is a uniform slip rate on these segments, then this model suggests that there should be more frequent earthquakes on the Cholame segment with smaller offsets. However, the findings imply that the San Andreas fault in the Carrizo may have actually ruptured more frequently than along the Cholame. Rupture scenarios that link the Cholame ruptures with Carrizo earthquakes fail to maintain a uniform slip rate if the offsets are characteristic, given this result. Scenarios that link Cholame ruptures with Parkfield earthquakes do not conform to a characteristic rupture length of the Carrizo events such as experienced in 1857.

When a magnitude 7 earthquake shook Loma Prieta California in 1989, seismologist Lynn Sykes, Higgins Professor of Earth and Environmental Sciences was at Lamont-Doherty. Since telephone lines and electricity were down at the U.S. Geological Survey in Menlo Park, California, Sykes could tell the size of the quake, but not which fault had ruptured or the length of the fault slip. "It took two days before I knew that, yes, my section of the San Andreas Fault had broken," Sykes recalls. "It was premature that evening to say our prediction had come true. It was a two-day intellectual experience we went through to realize, hey, this does have implications for long-term prediction of large earthquakes."

For years Sykes had studied the probabilities of large earthquakes along the San Andreas fault system, and since 1975 had seen in the Loma Prieta vicinity a build-up of moderate-sized quakes. In a 1984 paper with Stuart Nishenko "we put in a couple of lines to that effect: the pattern was reminiscent of what was seen before the great San Francisco earthquake of 1906, but over a smaller area, and could be a long-term precursor to a rupture of that segment of the San Andreas. So the calculation of stresses was something he pursued after that."

Not long after Loma Prieta, Sykes began to develop a model for predicting large earthquakes in California within approximately 30-year time-windows. "To what extent can earthquakes be predicted?" Sykes asks himself. "A number of my colleagues are less optimistic than I, and there's much divergence of opinion. Is prediction worthwhile? Yes, in terms of 10 years to a few decades. In terms of weeks, days, hours, that will take more time to develop."

Recently Sykes and Jishu Deng have completed a model of the evolution of stress fields in Southern California. The situation there is much more complex than in Northern California, with several types of faulting in close proximity. The model starts with a snapshot-in-time of an 1812 Wrightwood quake and projects through six large quakes (including Landers in 1992) and their resultant stress shadows. The model projects to a possible stress field environment in 2025.

Assuming a great shock has not occurred before 2025, the two scientists say, a candidate quake could be of about a 7.9 magnitude. Both the San Bernardino and Coachella Valley segments of the San Andreas Fault "are assumed to rupture in that earthquake." Stress has been accumulating along the Coachella Valley segment since 1690! And possibly along part of the San Bernardino. Deng and Sykes suspect large quakes in these regions could trigger shocks in other areas of Southern California, including the Los Angles Basin. And that's just the simple part of the "So Cal" model.

Can we fine-tune quakes predictions to shorter time periods? "If we lived in a wonderful world," Sykes says, "we'd have networks of measurments at depths of 5 and 10km at faults. There are only two places we now have even dense nets at the surface. At Parkfield, in central California, 7 to 10 things have been monitored continuously for 25 years. And as a result of Loma Prieta, there's been a realization the Hayward Fault has a probability of rupturing in the next 30 years. So more attention's been paid to it. But a section of the Peninsular San Andreas equally well deserves attention. There's a seismic network there, but not much else. We need to monitor 8 other areas where we we have a reasonable chance over the next couple of decades of catching one or a few large earthquakes in a really good observation network.

"We also need to study the fluid pressures at depth. How easy is it for a fault to move depends a lot on whether the fluid pressures are high or low; whether they change with time. We don't know that now. If fluid pressures are high, you don't need as much stress on the rock before slippage occurs. How often big earthquakes occur could well be governed by that."

In a less than wonderful world, attempts at very short term prediction -- weeks, days, or hours -- are probably a waste of time. "It's the mistaken belief that that the public wants them, or they're the only thing the public calls earthquake prediction," he notes. Many parts of society -- including government, construction businesses, utility companies -- can benefit by accurate 5 to 30-year predictions. "We've made the greatest progress in longer-term prediction, and I think we must take the slow but definite progress we have and work on those time-scales.

Maybe, just maybe the data I'm currently receiving may show me when the next large quake will center in the area. To date though I haven't seen anything would indicated a large quake at any of the areas I have forecasted for. I may not even be able to recognize if it were there ready to bite me as if it was a snake. Take Care…Don in creepy town