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Preliminary calculations indicate that, as of 12:00 pm (PDT) on Sept. 30, 2016, there is 0.006% to 0.2% chance (less than 1 in 10,000 to 1 in 500) of a magnitude 7 or greater earthquake being triggered on the Southern San Andreas Fault within the next seven days through October 7, with the likelihood decreasing over time. This range is estimated using several models developed in California to assess foreshock/aftershock probabilities, and the lower bound is about equal to the average chance of a magnitude 7 earthquake occurring on the Southern San Andreas Fault in any given week. These revised probabilities are lower than those made earlier this week, due to decreasing swarm activity. The probabilities may change if the swarm activity increases or decreases.” (USGS)
Earthquakes 1 week to ca 1245 UTC Oct. 3 Salton Sea earthquake swarm, nuclear, plate movements  faults to 15000 yrs ago Diablo Canyon quaternary faults less than 15000 yrs recent earthquakes Oct. 3 ca 1245 UTC Plate Motion, US W. Coast Earthquakes one week to Oct. 2 2016
Plate motion;
Quaternary Faults
Red lines: “Historic- Most recent, known movement less than about 150 years
Orange lines: “Holocene to Latest Pleistocene- Younger than 15,000 years
[Note orange lines offshore of both Diablo Canyon Nuclear Power Station and San Onofre Nuclear Power Station. Nearshore earthquakes could lead to tsunamis with no warning.]

More info on earthquakes and nuclear power stations in California, including more detailed faultline maps found here: https://miningawareness.wordpress.com/2016/06/12/california-nuclear-power-stations-and-the-earthquake-rupture-forecast/ https://miningawareness.wordpress.com/2015/03/11/california-largemega-quake-risk-nuclear-power-plants/ https://miningawareness.wordpress.com/2015/01/17/why-has-the-us-nrc-ignored-increased-west-coast-earthquake-hazard-two-decades-after-the-northridge-earthquake-years-after-fukushima/
Although San Onofre has been shut down, it still has high level nuclear waste on site.

The quake on the map nearest San Onofre Nuclear Power Station this week was actually a quarry blast undertaken after the earthquake swarm had started.
M 1.2 Quarry Blast – 7km ENE of Vista, CA
Time
2016-09-27 20:42:51 UTC
2016-09-27 13:42:51 -07:00 at epicenter
Location
33.233°N 117.175°W
Depth
-0.62 km (-0.39 mi)

Earthquakes in the Brawley Seismic Zone: Updated 09/30/2016

An earthquake swarm near Bombay Beach, California, started on Sept. 26, 2016, in the Brawley Seismic Zone, which lies near the southern terminus of the San Andreas Fault.

The swarm includes 96 earthquakes above magnitude 2 so far (as of 12:00 pm PDT on Sept. 30, 2016). Relocations of these events show that they are occurring in the depth range 4 to 9 km. The largest of these events were two M4.3 earthquakes and a M4.1 earthquake on Sept. 26.

The earthquakes are occurring near a set of north-northeast trending cross-faults beneath the Salton Sea. The cross-faults are part of a fault network that connect the southernmost end of the San Andreas Fault with the Imperial Fault. Some of the cross-faults are oriented such that they add stress to the San Andreas Fault and the San Jacinto Fault system when they rupture in small earthquakes like those in the ongoing swarm.

Swarm-like activity in this region has occurred in the past, so this week’s activity, in and of itself, is not necessarily cause for alarm.

Preliminary calculations indicate that, as of 12:00 pm (PDT) on Sept. 30, 2016, there is 0.006% to 0.2% chance (less than 1 in 10,000 to 1 in 500) of a magnitude 7 or greater earthquake being triggered on the Southern San Andreas Fault within the next seven days through October 7, with the likelihood decreasing over time. This range is estimated using several models developed in California to assess foreshock/aftershock probabilities, and the lower bound is about equal to the average chance of a magnitude 7 earthquake occurring on the Southern San Andreas Fault in any given week.

These revised probabilities are lower than those made earlier this week, due to decreasing swarm activity. The probabilities may change if the swarm activity increases or decreases.https://earthquake.usgs.gov/misc/2016-09-27.php

USGS Stress Buildup California
The constant plate tectonic motions between the Pacific and North American plates guarantees that the crust in the western US is continually building up stress. The image of crustal velocities provided by extensive GPS coverage reveals where these velocities change rapidly over short distances, demanding that the intervening crustal rock stretch and build up stress over time. Such a map of the stress reveals two main lines where stress is concentrated: The San Andreas fault zone and the Eastern California Shear Zone. These zones have experienced numerous earthquakes over the century and a half that earthquakes have been historically observed.

The mechanism of stress buildup within these fault zones is uncertain. One hypothesis is that the hot rocks below the upper 15-km-thick layer (the upper crust that has the vast majority of continental earthquakes) flows continually in response to periodic earthquakes, forcing the upper crust to bend with this flow. Another hypothesis is that slip of the deeper continuation of faults, steady slip that doesn’t produce earthquakes but still involves motions across the fault, forces the upper crust around the faults to bend and thus concentrate stress. Both hypotheses are the subject of active research. But the fact remains that high stressing rates observed on the surface likely translate to high stressing rates at the depths (~10 km) where earthquakes typically nucleate, so these stressing rates are a guide to the seismic hazard.http://earthquake.usgs.gov/research/eqproc/trackingstress.php

https://en.wikipedia.org/wiki/Rancho_Seco_Nuclear_Generating_Station
https://en.wikipedia.org/wiki/Trojan_Nuclear_Power_Plant