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Napa Earthquake and Future Earthquakes in Northern California

The figure below from the Bill Ellsworth at the USGS is a depiction of the earthquake history of Northern California up to about 1990.  In the Bay Area, the last earthquake of significance was the magnitude ~6.9 Loma Prieta earthquake of October 17, 1989.  Last sunday's magnitude 6 Napa earthquake was in fact the strongest earthquake north of San Francisco and south of Eureka  since 1906. 

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Building Damage in the Napa Earthquake

One of the questions we are often asked is whether one should buy earthquake insurance, or put the money into seismic retrofitting.  While this is a question for the individual, we can show that retrofitting can save considerable money by reducing damage.

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Quakeworks Mobile App

If you want the mobile version of the earthquake forecast/home damage estimator on this web site, go to the Apple App Store and download the "Quakeworks" app by Open Hazards.

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Magnitude 6.0 Earthquake, Napa, California, August 24, 2014

Major earthquake this morning on the West Napa fault.  Earthquake occurred at 3:20 am this morning.  Here in Davis, it was felt by many.  It is reported that there are at least 89 injuries in Napa, with widespread damage in the downtown area.  The fault crossed at least one road in the area, and showed evidence of right-lateral slip.  Many water mains broke, and there are reports of 50 gas line breaks and fires as a result.

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Update on the M5.3 Orkney, South Africa Earthquake

Below are updates on the figures from the last post on the Orkney, South Africa earthquake.  As can be seen, the probability of an M>5 earthquake within the same 100 km circular region has decreased from 68.1% to 44.9%, which is consistent with the way the forecast algorithm works. 

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M5.3 Earthquake, Orkney, South Africa, August 5, 2014

The largest earthquake to strike South Africa in 40 years killed one man and injured 17 others today.  Located near the town of Orkney, it was widely felt.  Here we use the hazard viewer to review the forecast preceding the event.  Note that the forecast was previously updated last night on August 4, so the data on the web site represent the pre-event probabilities.

In the image below, we show the location of the event together with the forecast contours.  The earthquake occurred on top of the only prominent hotspot in South Africa.

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Bad Day Fishin’

It is said that  “A bad day of fishing is better than a good day of work”.  I won’t argue, but if you were trolling for trout at Chehalis Lake, British Columbia on December 4, 2007, you’d have had a bad day. Chehalis Lake, 50 miles east of Vancouver is a lovely spot nestled in the mountains. Prior to that date, it was known mostly to fisher folk and 4 wheel drive enthusiasts.

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Super Typhoon Rammasun Approaching China, July 18, 2014

Information and updates on Super Typhoon Rammasun can be found here.  Data on Open Hazards web viewer from GDACS.  Super typhoon Rammasun making landfall in China.  Typhoon Matmo heading for Taiwan.

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Update on the M6.5 Namie, Japan Earthquake of July 12, 2014

It is interesting to compare the pre- and post- event forecast probabilities for the Namie, Japan earthquake.  As readers of this blog will know, probabilities in the forecast here change when a large event occurs.  For the M6.5 earthquake that occurred last saturday, probabilities for M>6 earthquakes decreased, whereas probabilities for the M>7 earthquakes increased slightly.  The changes can be seen in the attached comparison screenshots.

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Magnitude 6.5 Japan Earthquake

We have only been here in Kyoto and Sendai, Japan, 10 days and so far have experienced a super typhoon (Neoguri) and now an earthquake.  This morning, I went down to the 26th floor of our hotel here in Sendai, to photograph the rising sun.  Just before 4:00 am, the building started moderate shaking, which continued for about 20 seconds.  It turned out to be a magnitude 6.8 earthquake (later downgraded to a magnitude 6.5 event) in the trench.  I am here to give a series of lectures at Tohoku University on earthquake forecasting, so it was timely.  No damage or injuries, and no significant ts

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