Blogs

The Open Hazards Group is excited to partner with the Association of Pacific Rim Universities (APRU) to contribute to the new Multi-Hazards Program as described here.  The APRU is comprised of the 42 leading universities around the Pacific Rim.  The new initiative grew out of discussions initiated by APRU Secretary General Dr.

Its really simple.  You can see earthquake probabilities for your own or any other location. Here are the steps.  We will use the Circle Selection Tool to define a circular region.

1.  Roll over the the Tools tab at the top to see the drop down menu.  Click on the words Earthquake Viewer.

2.  You will see a Google map.  Look to the left side of the map.  Under the "Earthquake Hazard" heading, locate the Circle Selection Tool.  Click on the adjacent little box to the left side.

To further investigate the data underlying the forecast, we defined a polygon of (lat,long) pairs around the main islands of Japan.  These (lat,long) pairs are given by: (34.3,128.2), (38.0,136.8), (45.6,141.0), (42.9,147.7), (32.0,145.5), (27.5,131.5).  These were entered into the ANSS User Interface.  We found the following for the earthquakes occurring from just after the M9.1 event on 3/11/2011 through 12/29/2012 (Note that there is no data in the catalog from 12/30/2012 through today, 1/28/2013): 911 events with M>5;   94 events  with M>6; and 6 events with M>7. 

I read that Hurricane Sandy inflicted 50 billion dollars of property damage. I don’t know what fraction of the 50 billion was purely wind-sourced versus the fraction caused by storm surge. Certainly, the most graphic pictures of the damage in my mind are the homes tossed helter-skelter by the latter. A close second are images of businesses and houses sitting 6 or 8 feet deep in muddy water.

Unfortunately it is very possible, at least according to the calculations on this web site.  We can use the earthquake viewer, found under the "Tools tab", to define a selection polygon in the Japan region (Figure 1 below).  A relatively recent addition to the viewer tool then computes the numerical probability for events M>5, M>6, M>7, and M>8 for time periods 1 month from now, 1 year from now, and 3 years from now, occurring within the defined region.  Figure 1 below shows that the probability for an M>8 earthquake is very high.

In the December 29, 2012 blog we saw that earthquake probabilities have changed dramatically in the region devastated by the March 11, 2011 earthquake and tsunami off the Tohoku coast of Japan.  It is therefore interesting to see that the chance of a M>6.5 earthquake during the next year seems to be increasing in the area of Tokyo and Chiba, Japan, even over a period as short as 2 weeks.  The screenshots below document this change. 

Many of my blogs involve natural disasters either hypothetical or long past. In a workaday world, it’s understandable for one to be blasé about such things. Sure, ‘what if’ events are possible, but why care?

To counterbalance this tendency, I like to highlight cases where

                                ‘What if’   became   ‘Just did’

The figure below shows the time-dependent changes in spatial forecast contours associated with the M7.7 Prince Rupert, Canada (10/27/2012) - M7.5 Craig, Alaska (1/5/2013) earthquake sequence.  The Prince Rupert earthquake was an oblique-thrust (compressional) event, whereas the Craig earthquake was a right lateral strike (horizontal) slip event. Of concern, the forecast contours representing chance of an earthquake correspond to a higher probability down towards the southeast, nearer to Vancouver and Seattle.

An M7.5 earthquake has just occurred off southern Alaska at 8:58:16 1/5/2013 UTC (11:58:16 pm 1/4/2013 local time), just at the NW tip of the area identified in the previous blog as having undergone a rapid change in the last several days. Hypocenter depth was 9.9 km, and a tsunami warning has been issued.  More as the story develops. A screenshot from the earthquake viewer is shown below.  The mechanism for this event was right lateral strike slip (horizontal slip) so a great tsunami is probably unlikely.

As readers of this blog know, I've been following locations of several large earthquakes to document time-dependent changes in local spatial forecast contours.  Two weeks ago, we looked at the Prince Rupert, Canada area, site of the M7.7 earthquake that occurred near the Queen Charlotte Islands fault zone on 10/27/2012, causing a minor 1 meter tsunami in regions as far away as Hawaii.  Forecast probabilities for future M>6.5 events over the next year and within 50 km seem to be adjusting and changing rapidly at the moment.