john's blog

Image from the NASA MODIS instrument on the Acqua satellite.  The fire continues to burn out of control. More details here.

Recently the science community has developed a new way to image the ground displacement from earthquakes.  It's called  Synthetic Aperture Radar Interferometry, or InSAR for short.  In fact NASA has recently signed an agreement with the Indian Space Agency to fund the launch of a radar satellite for earthquake and climate studies.

Two interesting stories today, one in the Sacramento Bee newspaper, and the other on Reuters.  The consumers quoted in the stories do not think insurance is worth the cost.  The providers of insurance urge more people to sign up.  What most people also don't realize is that no reimbursement for loss of contents will occur until after the deductilble on the structual damage is met.

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. 

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.

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.

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.

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. 

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.

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.