Earthquake Forecasts: Upgrades, Enhancements, Bug Fixes

Those visitors who have been regular readers of these pages will see significant differences in the forecast contours appearing in the hazards viewer, also reflected in some differences in the forecast probabilities. 

The colors are generally brighter, with the red colors reflecting the fact that probabilities of significant earthquakes in these regions are higher.

For the California forecast shown at right, the contours represent the probability of a region experiencing a M>5 earthquake within 1 year of today, June 8, 2013.

As before, there is a "roll back" button on the upper left side of the viewer that allows the user to view the contours as they were at dates up to 5 years earlier than the present. 

Also as before, probability values are available via the GetEarthquakeProbability API under the Data Tab.

For some time, we have been concerned that poor catalog data quality for small earthquakes in many parts of the world limited the accuracy of the forecasts.  This problem was raised in a blog on these pages on May 14, 2013. 

We use small earthquakes to forecast the large earthquakes, going back to 1980. However, digital data was not available prior to about 1990.  In addition, station coverage in many areas of Asia is still inadequate. 

These problems particularly affect the small earthquakes in the catalogs.  In many cases, many of the small earthquakes are missing from the catalogs at earlier times.  Hoever, the catalogs are generally much more complete at the largest magnitudes, as might be expected, since these can be detected with thd global networks. 

So we were motivated to develop a hybrid approach in which we use small magnitude earthquake data in circumstances that allow it, and large magnitude data when the small magnitude data is inadequate. 

We also wanted to develop a contouring scale that more accurately and uniformly reflected the level of hazard and risk in various parts of the world. 

Two of the results can be seen in the screenshots in this article.  I will be exploring many of the consequences of these changes in future blogs. 

At left you can see the updated contours for Japan.  These contours represent the probability of experiencing a M>6.5 earthquake within 1 year of June 8, 2013.

We are also in the process of preparing publications on these matters for the professional peer-reviewed literature, as well as for presentations at professional meetings.

The large red region is the source area of the March 11, 2011 M9.1 Tohoku earthquake. 

As I have discussed previously (blogs on January 8 and January 24, 2013), the greater Japan region is at serious risk of another great M>8 earthquake within the next year or two. 

The 600 km deep M8.3 Kamchatka earthquake of May 24, 2013 did not significantly decrease the probability of such an event.  It may in fact have increased it, at least according to the probabilities that we compute.

We hope that you will find these enhanced and upgraded forecasts to be of value.  We will continue to strive to improve our understanding and capabilities to compute earthquake forecasts. 

It is our strong desire to provide you with the tools and information to make your lives safer from these devastating natural disasters.