Earthquakes

According to yesterday's article about the 3.3M earthquake, we are 100 years over due for a magnitude 7+ earthquake in this fault zone. How did they figure that? Using the 142 year interval with the last huge earthquake in the same zone occurring in 1857 (Fort Tejon), by my calculation next next big one should have happened in 1999. Therefore, we are only 7 years over due. Can anyone explain?

A.
They're government subsidized
B.
They're PHD's and paid to think like that
C.
Job security
D.
All of the above

Mathematics and educated guesses are not portrayed as predictions, but estimates of how often they occur. Take it with a grain of salt and know it could happen at any moment. Are you prepared?

For up to the minute earthquake information go to http://earthquake.usgs.gov/eqcenter/

It shows all the quakes for the last hour, day and week. Click on the squares in the area of interest and it will bring you to the most local, where you can get the information about the specific quake and its location. In fact, we had one in So Cal in the last hour. The rest of the site has interesting facts and information as well.

I don't understand the first part of that paragraph because the 1857 Fort Tejon quake was further up the line on The San Andreas Fault well after the two faults merge. The part from Scripps refers to the San Jacinto fault zone that runs from Cajon to the around the CA-Mex border. Which part they are specifically most worried about I'm not sure but I think it's us.

This is a pretty cool site for lots of the SoCal faults.

http://www.data.scec.org/faults/faultmap.html

Based on extensive paleoseismic work at Wrightwood (San Andreas fault), the average interval between ground-rupturing earthquakes in that area on the San Andreas fault is about 105 years (based on dozens of earthquakes they have studied).

Here's a link to the scientific summary: http://www.gsajournals.org/gsaonline/?request=get-documen...(2004)014%3C4:WATECW%3E2.0.CO;2

Since the last earthquake to rupture into the Cajon Pass region was in 1857, that region is significantly over the 105 year average already. Slightly farther south in the SB region the last earthquake was in the 1600s. Assuming the rupture interval for that segment is in the same range, that segment is about as overdue as is statistically likely.

Interestingly, the Wrightwood trenches revealed that the longest interval between earthquakes since about 700 A.D. is about 162 years (remembering that the average is 105 years), and the second longest was 150 years. This year we mark the 149th year since the last EQ (1857). Based on this evidence, my money is that it will happen sooner (in the next decade) rather than later. You should be fully prepared because the science shows it is expected at any time.

But the name Fort Tejon is something of a misnomer. The epicenter was thought to be further north, a bit south of Parkfield. Ft. Tejon is where the most damage occurred and a death. There would have been worse damage closer to the epicenter but it was VERY sparsly populated.

The quake you need to look at is the 1812 Wrightwood Quake est. 7.5 mag.

"Often referred to as the San Juan Capistrano earthquake, due to the death toll from the quake at that famous mission, the exact location and size of this earthquake are unknown, but based upon evidence from sediments along and tree-rings of pines growing near the San Andreas fault, this quake has been identified as one along the Mojave segment of the San Andreas, possibly resulting in as much as 170 km (106 miles) of surface rupture -- roughly, that length of the fault between Tejon Pass and Cajon Pass -- with a theorized epicenter near Wrightwood."

What is mind boggleing about the Ft. Tejon quake is the number of deaths of people standing around in the open. No structures to fall on them. I cannot imagine a lethal ground movement in the open.