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Magnitude 7.5 Earthquake near Papua, New Guinea April 19, 2014

A strong earthquake occurred near Papua New Guinea a few hours ago on Saturday Apr 19 2014 at 06:27:59 GMT-0700 (PDT).  From the Hazard Viewer we can do a simple but rapid analysis.  The forecast from the Hazard Viewer was computed last night at midnight, a few hours prior to the earthquake.  The earthquake locations are shown below, with the bright red event being the M7.5 mainshock:

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Mexico Earthquake Magnitude 7.2, April 18, 2014

Two hours ago a magnitude 7.2 earthquake struck near Galeana, Mexico.  It shook both the nearest city of substantial size, Tecpan, as well as the capital of Mexico city.  The latter is located on an old lake bed and is subject to amplified shaking due to the thick layer of sediments.

From the Hazard Viewer, it can be seen that the earthquake struck in an area of elevated probability:

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Oklahoma is the most Seismically Active State in the USA

To those of us studying California earthquakes during the last 30 years, this is really weird.

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Fracking, Wastewater Injection, and Earthquakes

I was just reading an interesting article on wastewater injection and earthquakes.  The process of fracking, that is fracturing tight shales to allow hydrocarbon production, can involve the production of large volumes of waste fluids.  These are then typically re-injected into the ground.  The injected fluid has been shown in some areas to lead to increases in the number of earthquakes.  Examples are the Rocky Mountain arsenal in February 1966, and Basel Switzerland in 2009.

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Chile Earthquake Magnitude M7.8 Aftershock

Some computations from the hazard viewer.  This event is much closer to Iquique than the mainshock, probably more damage.

(Update  21:29 PDT: Magnitude now downgraded to 7.6)

Events and forecast map, together with selection circle.

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Chile Tsunami Should be Approaching Taiwan Now

From NOAA.  Posted at 15:33 on 4/2/2014

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Chile Earthquake filled an Old Gap

This slide is from a compilation by the IRIS consortium


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Chile Earthquake Seismic Gap

One of the theories about earthquake occurrence over the years is that seismic gaps develop between major and great earthquakes, and are eventually filled.  With that in mind, it is interesting to plot the approximate slip planes for both the M8.8 earthquake of 27 February, 2010, and today's M8.2 earthquake of April 1, 2014.

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More on M8.2 Chile Earthquake - There were Foreshocks

Defining the polygon below:

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Magnitude M8.2 and Tsunami, Iquique Chile, April 1, 2014

Earthquake in Chile with tsunami watch and warning.  Areas of the Pacific should take precausions, including Hawaii and Japan, among other areas.  Depth shallow, about 10 km.  Screenshot of earthquake location below, with forecast contours for M>6.5.  The forecast was computed at midnight last night - forecasts are updated every night at midnight California time.


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