john's blog

It was just reported that a M7.3 earthquake struck at 8:18:25 GMT off the eastern coast of Japan, in the area of the March 11, 2011 event.  A 1 meter tsunami was reported as well, with at least 1 M6.2 aftershock.  We had been expecting an event rather like this one, as shown by the figure below. I am still at the AGU meeting where a most interesting set of presentations on the March 11 event were given yesterday. 

Latest word is that more than 22,000 attendees are expected at this years' meeting.  I went to some interesting talks on the March 11, 2011 M9 Tohoku, Japan earthquake this morning.  It seems that there was evidence of slow ("aseismic") slip prior to the earthquake, according to Yoshihiro Ito and colleagues from Japan.  There were two events in the years preceeding the mainshock. Both events were seen on ocean bottom pressure transducers, and on-shore volumetric strainmeters.

About 19,000 registered attendees last year at the American Geophysical Union meeting at the Moscone center in San Francisco, and probably 22,000+ attendees this year.  The problem is, how do you accomodate all those scientists who want to present their research?  The answer (at least it has been for a couple of decades) is poster presentations.  This solution now looks like it has gotten to its obvious overwhelming stage -- thousands of posters every day in a cavernous poster hall.  My poster was number 2518, the image below is about 1/5 of the poster hall. 

The American Geophysical Union meeting in San Francisco is an annual event that I have been attending since 1974.  My first meeting was at the old Jack Tar hotel on Van Ness in 1974.  From there it spread to the Holiday Inn on Van Ness, then to the Civic Center Auditorium, and since about 15 years ago it has been at the Moscone Center. With an attendance of over 22,000 scientists this year, it is one of the largest meetings of its kind in the world. 

Spatial probability contours can be seen by using the Earthquake Viewer tool under the tools tab.  In previous blogs, I have examined the change in spatial probability contours as they evolve over time.  Here I summarize the changes over just a few weeks from 9/29/2012 to 11/23/2012.  The changes are subtle but nevertheless visible. 

On November 10, 4 days ago, a M6.8 earthquake struck Myanmar (Burma).  A friend of mine currently living in Bangkok happened to be in Mandalay and felt it strongly.  It is interesting to compare the changes in forecast contours for this region after only 4 days to the contours from Guatemala as described in the previous posting.

For the Myanmar (Burma) area, the epicenter of the quake is shown by the orange arrow.  Clear changes in contours can already be seen in the region after only 4 days (red boxes).  Recall that the contours are for M>6.5 earthquakes over the next year.

As summarized below, the Guatemala earthquake of 11/7/2012 was a M7.4 event in which several tens of persons perished, with more injured.  It was followed several days later by a M6.5 aftershock.  Below we show a comparison of forecast contours for this event, comparing the pre-mainshock contours on 11/7/2012 with those from today, 11/14/2012. 

Today at 16:35:50 GMT, an earthquake with magnitude M7.4 occurred offshore of Guatemala.  It was felt as far away as Mexico City.  In the figure below, I have used the earthquake viewer to snap some screenshots of the global forecast contours for an M>6.5 earthquake within the next year.  The contours are pre-earthquake contours, since they were updated at midnight last night.  We will see how the probabilty contours evolve over the next few days.

Image below shows the change in forecast contours over 7 days following the October 27, 2012 M7.7 Prince Rupert, British Columbia earthquake.  Contours representing probabliities of future earthquakes in the region are continuing to change rapidly.  The red star denotes the epicenter of the M7.7 event.  The images below are screen shots from the earthquake viewer.  Site visitors can repeat this type of analysis for themselves in any world wide location.

Changes from September 29, 2012 thru today, November 2, 2012.  Red boxes indicate areas that some of the changes can be seen.  Both increases and decreases in contours can be seen.