<p>The probabilities are generally based on long term recurrence rates. You can read about the details in the Working Group on Earthquake Probabilities page <a href="http://www.wgcep.org/components-EQ_probability_model" rel="nofollow">Earthquake Probability Models</a>. </p>

<p>The last major earthquake on Southern SAF was in 1857 which means that the average slip deficit on the fault is around ~8.0 m (the Pacific plate is sliding past at a rate of 55 mm/yr). Using empirical scaling laws you can estimate the magnitude of the earthquake that is required to release the accumulated strain. However, the 8.0 m slip deficit is an upper bound as some of the deformation in the region is accommodated by other fault systems, e.g., Elsinore and San Jacinto faults (sub-parallel to SAF) as well as the Eastern California Shear Zone which was the site of Landers/Hector Mine earthquakes in the 90s.</p>

CC BY-SA 3.0
2015-02-05T19:54:12.500Z
Thank you - it will take me a while to understand the link, but I follow the concept.  There appear to be (at least two possibilities: one is that part of the San Andreas ruptures every 150 years, the other is that when the whole fault has ruptured, (which it has since 1680) there is a lull before it starts rupturing again.  Is this correct?
Daijohn
CC BY-SA 3.0
2015-02-03T02:31:36.130Z
2015-02-03T06:20:06.823Z
2015-02-03T06:20:06.823Z
stali
<p>A recent report estimated the probability of an earthquake greater than magnitude 7 on the southern section of the San Andreas fault at approximately 60% over the next thirty years.  How is that probability calculated?</p>

CC BY-SA 3.0
2015-02-03T01:47:22.560Z
Please provide a reference for your report
arkaia
<seismology>
Earthquake probabilities
Daijohn
# Earthquake probabilities

(Asked by: username_0 on 2015-02-03)

A recent report estimated the probability of an earthquake greater than magnitude 7 on the southern section of the San Andreas fault at approximately 60% over the next thirty years. How is that probability calculated?

**Tags:** seismology

> **Comments:**
> **username_1**: Please provide a reference for your report  

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## 1 answers

### Answer by username_2 on 2015-02-03. Score: 6 | Accepted answer

The probabilities are generally based on long term recurrence rates. You can read about the details in the Working Group on Earthquake Probabilities page [Earthquake Probability Models](http://www.wgcep.org/components-EQ_probability_model).

The last major earthquake on Southern SAF was in 1857 which means that the average slip deficit on the fault is around ~8.0 m (the Pacific plate is sliding past at a rate of 55 mm/yr). Using empirical scaling laws you can estimate the magnitude of the earthquake that is required to release the accumulated strain. However, the 8.0 m slip deficit is an upper bound as some of the deformation in the region is accommodated by other fault systems, e.g., Elsinore and San Jacinto faults (sub-parallel to SAF) as well as the Eastern California Shear Zone which was the site of Landers/Hector Mine earthquakes in the 90s.

> **Comments:**
> **username_0**: Thank you - it will take me a while to understand the link, but I follow the concept.  There appear to be (at least two possibilities: one is that part of the San Andreas ruptures every 150 years, the other is that when the whole fault has ruptured, (which it has since 1680) there is a lull before it starts rupturing again.  Is this correct?  

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