April 16, 2018
California is beginning to see a slight increase in seismic activity, along with a noteworthy increase across the whole of the West Pacific (as expected).
Over the past few hours two back to back earthquakes measuring near M4.0 (M3.9 + M3.8) were detected and felt across the West Coast of the United States in the state of California.
The two felt events struck Central, and Northwest California from San Francisco to San Joaquin valley.
Information on both earthquakes comes from the USGS:
The fact that California is now showing an increase in seismic activity coincides with the noteworthy increase in magnitudes, and frequency of occurrence in the West Pacific.
The number of M5.0+ earthquakes, and the number of deep events is on a definite upswing over the past 48 hours. (See below graphic)
This past week (last 7 days), there was a noticeable decrease in activity. The decrease was shown in this weeks earthquake forecast video, and was a topic of discussion.
As it was noted in this weeks global earthquake forecast, we were expecting a noteworthy increase in earthquake magnitudes, and number of events due to multiple new deep earthquakes which struck across the Pacific.
[At least six different deep events struck below the Pacific plate at depths from 250km all the way up to near 550km.]
Deep earthquakes cause shallower larger earthquakes, therefore the seismic increase is occurring just as we would expect — happening in areas surrounding the deep events.
The deep earthquakes put the plate into motion, which then perturbs adjacent plates such as North America, thus causing new earthquakes with larger magnitudes than the previous week.
What do Deep earthquakes do?
Deep earthquakes occur in an area called the “asthenosphere”, even though these earthquakes are not felt by humans, these deep events place upwards pressure on the underside of the plate(s) causing shallower larger earthquakes (up to 1-2 magnitudes larger).
Shallow larger earthquakes can strike in the same location as the deep earthquake, or the nearest silent zone fulcrum point.
There is additional compensation movement of similar size which occurs on the OPPOSITE side of the Pacific plate when a large OR deep earthquake occurs.
Imagine the deep earthquake like a lava lamp ball rising up to the crust of the earth. Deep earthquakes can be recorded up to 750km. Asthenosphere deepest is 660km.
Leverage , along with Torque is the key, physics dictates these actions:
Here is a conversion chart , a guide for calculating depth into Magnitude increase.
This chart was developed by earthquake forecasting researchers Bella Virgo and Rebecca the Explorer:
NOT INTENDED FOR COPY unless otherwise granted permission by the creators of this chart