john's blog

Here we give an earthquake forecast for the four southern California cities of Los Angeles, Riverside, Palm Springs and San Diego.  These forecasts are for large earthquakes having magnitudes M>6 within a 100 mile radius of those cities, occurring within the next 12 months. A previous post gave earthquake forecasts for the 4 northern California cities of San Francisco, Berkeley, San Jose and Sacramento. 

The last major earthquake in the California-Nevada region was the April 4, 2010 El Mayor-Cucupah (Baja) earthquake.  With a magnitude M=7.2, this event did over USD$100 million in damage to the surrounding region.  Its effects are still being felt in the enhanced number of smaller earthquakes that have occurred since that date.

On October 20, 2011 two moderate earthquakes struck beneath Berkeley, California at depths of 9 to 10 km. The first of these events registered a magnitude of 4.2, with the second one a 3.8.  While small to moderate, these events were apparently felt as far away as Portland, Oregon.  

My father was one of the original Hurricane Hunters.  As a young man, he had been drafted into the army near the close of World War II.  He was assigned to the Army Air Corps and decided to apply for training as meteorologist.  He recalls flying in B-17s and other aircraft as part of his assignments.

Readers of these blogs have seen a series of four cities earthquake forecasts for California, Japan, Greece, Italy and Iran among other countries.  This updated forecast represent the chance of an earthquake during the next 12 months within 150 miles of four California cities, for magnitudes 7.0 and larger. 

In 2008, the US Geological Survey published a map of probability of ground motion over the next 50 years.  The map was based on historic earthquakes as well as recent seismicity (smaller earthquakes).  The area hit by todays M5.8 earthquake was identified as the most likely location in that region.

The map from the USGS is below:

By now, everyone in the United States knows that significant earthquakes can happen on the east coast.  It might be prudent to recall other major earthquakes that have occurred east of the Rocky Mountains.  These included the M~7.5 earthquakes in New Madrid, Missouri during 1811-1812, the M6.5 Cape Ann earthquake of 1755 that occurred off the coast of Massachusetts, and the M7.3 earthquake the destroyed Charleston, SC on August 31, 1886.

Yesterday the city of Springfield Massachusetts was struck by a tornado.  Four persons lost their lives, and damage was substantial.  Videos of the event are dramatic.  Tornadoes are another example of the vagaries of mother nature, along with earthquakes, tsunamis, and hurricanes. 

As if Greece didn't have enough problematic issues.  Economic problems and the Eurozone.  Out-of-control wildfires.  Today's credit rating downgrade.  And of course, earthquakes.  As most geologists and seismologists know, Greece is situated near the collisional boundary of the African and the Aegean Sea tectonic plates.  Major earthquakes have occurred throughout Greek  history, causing major damage and loss of life. 

Recent news articles have told the story of an internet rumor popular in Italy at the moment, discussing the possibility of a major earthquake in Rome, Italy, proposed to occur on May 11, 2011 (see for example: http://www.livescience.com/14079-chance-11-earthquake-rome-usgs-bernandi...).  In light of the M6.3 L'Aquila earthquake of April 6, 2009, it seems timely to examine the chance of a major earthquake strking one of four principal cities in Italy.