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Steve's picture

Levee Break – San Francisco?

With all the news about Central United States flooding and Mississippi levee breaks, I thought that it might be instructive to run a levee failure simulation that could pique interest of folks in Central California.

The example is hypothetical, but imagine….

(1) A levee spanning the Golden Gate where the Golden Gate Bridge now stands.

(2) San Francisco Bay drained to bottom, and the region developed and cultivated like the lands of Santa Clara Valley further to the south.

john's picture

Four Cities Forecast: Greece (May 10, 2011)

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. 

john's picture

Four Cities Forecast: Italy (May 9, 2011)

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.

john's picture

Four Cities Forecast: Iran (May 9, 2011)

Previous posts in this series have been focused on cities in California and Japan.  Here we venture to another part of the seismically active globe, the middle east, and more particularly, Iran.  In recent news items, the government of Iran has proposed building nuclear reactors for power generation.  These would probably be located near the Persian Gulf coast, for proximity to cooling water.

john's picture

Four Cities Forecast: California Update (April 25, 2011)

Previous postings in this series have presented forecasts for the four California cities of Los Angeles, San Francisco, San Diego, and Sacramento.  Forecasts are for earthquakes having magnitudes M>7, within 150 miles (243 km), and within 1 year from the present.  The last such posting was made on March 14, 2011, shortly after the great Tohoku, Japan, M9 earthquake. 

john's picture

Forecast Verification and Validation via Backtesting

A critical component of any forecast program, in any field, is verification and validation.  Many of the standard methods are listed at http://www.cawcr.gov.au/projects/verification/.  Although this site is concerned primarily with testing of weather and climate forecasts, the methods are general and have been adopted by, and applied to data from, many fields, including finance, earthquakes, and social systems.

john's picture

Japan Four Cities North Forecast: April 12, 2011, Magnitude > 6

In previous blogs, this writer has focussed on larger earthquakes, those having magnitudes M>6.7 and M>7.0  In this and the companion blog, we compute the probabilities for M>6.0 earthquakes in the "south-central" four cities of Miyazaki, Tokushima, Osaka and Nagasaki. 

john's picture

Japan Four Cities South Forecast: April 12, 2011, Magnitude > 6

In previous blogs, this writer has focussed on larger earthquakes, those having magnitudes M>6.7 and M>7.0  In this and the companion blog, we compute the probabilities for M>6.0 earthquakes in the "south-central" four cities of Miyazaki, Tokushima, Osaka and Nagasaki. 

Unlike the "north" four cities of Tokyo, Nagoya, Niigata and Sendai, it is likely that most M>4 earthquakes have been included in the catalog, so the probabilities appear to this writer to be reasonable.  Here is the data, presented as usual in both time-series (line chart) format and table format.

john's picture

Japan Four Cities North Forecast: April 17, 2011 (Updated from April 9)

Similar to the previous forecasts for Reader of this blog have seen a series of forecasts for groups of four cities in California and in Japan.  The Japan forecasts have been for the cities of Tokyo, Osaka, Niigata and Sendai.  Computations were made for the chance of earthquakes having magnitudes larger than 6.7, over the next 12 months, within 150 miles, and whose hypocenter (location of initial slip) is less than 30 km (18 miles).

john's picture

Japan Four Cities South Forecast: April 17, 2011 (Updated from April 9)

Similar to the previous forecasts for the four central-northern cities, we compute the probabilities for the four southwestern, Japan cities of Miyazaki, Nagasaki, Osaka, and Tokushima.  Here it can be seen that the largest probabilites are for Miyazaki and Nagasaki. 

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