Geological evidence for past earthquakes in Tokyo region

Jan 31, 2012

In 1923, a magnitude 7.9 earthquake devastated the Tokyo area, resulting in more than 100,000 deaths. About 200 years earlier, in 1703, a magnitude 8.2 earthquake struck the same region, causing more than 10,000 deaths.

These earthquakes, which occurred just south of the area hit by the March 2011 , were produced by slips on the boundary between the subducting Philippine Sea plate and the overlying plate.

To estimate the average recurrence time between earthquakes in this region, and thus learn more about , scientists need to know when earthquakes occurred before 1703. There are few historical documents describing earlier earthquakes, though some records indicate that earthquakes occurred in 1293 and 1433.

To learn more about past earthquakes, Shimazaki et al. analyzed cores about 2 meters (6.6 feet) long from eight tidal flat sites on the Miura Peninsula in Japan. Their cores contained layers of shell-filled gravel that the researchers infer were deposited by tsunamis associated with the 1703 and 1923 earthquakes, as well as a third layer of tsunami-deposited material. The authors used dating to date the third event to sometime between 1060 C.E. and 1400 C.E. That is consistent with a large earthquake having occurred in 1293. If so, that indicates that the recurrence interval of these earthquakes varies from about 200 to about 400 years. The study could help scientists assess the earthquake and tsunami hazard in the Tokyo area.

Explore further: NASA sees Tropical Storm playing polo with western Mexico

More information: Geological Evidence of Recurrent Great Kanto Earthquakes at the Miura Peninsula, Japan, K. Shimazaki and H. Y. Kim, Journal of Geophysical Research-Solid Earth, doi:10.1029/2011JB008639 , 2011

add to favorites email to friend print save as pdf

Related Stories

Ill. earthquake a wake-up call

Apr 20, 2008

A U.S. seismologist said the earthquake that jolted the Midwest Friday is a reminder of the risks seismic events pose outside familiar quake areas.

Relationship between two recent New Zealand earthquakes

Sep 26, 2011

The relationship between two earthquakes that took place near Christchurch, New Zealand, in September 2010 and February 2011 is examined in a paper published in Scientific Reports. The findings suggest that t ...

1755, 2007 European earthquakes compared

Jul 02, 2007

An Italian-led team of seismologists has conducted a study comparing a 2007 earthquake off southwestern Portugal with a similar 1755 earthquake.

GPS data reveals more on mega-thrust earthquakes

Apr 29, 2011

(PhysOrg.com) -- New GPS data of the 2010 earthquake that devastated parts of Chile and killed over 500 people is revealing new clues about large earthquakes such as the quake in Chile and the magnitude 9.0 ...

Recommended for you

Kiribati leader visits Arctic on climate mission

3 hours ago

Fearing that his Pacific island nation could be swallowed by a rising ocean, the president of Kiribati says a visit to the melting Arctic has helped him appreciate the scale of the threat.

NASA catches a weaker Edouard, headed toward Azores

19 hours ago

NASA's Aqua satellite passed over the Atlantic Ocean and captured a picture of Tropical Storm Edouard as it continues to weaken. The National Hurricane Center expects Edouard to affect the western Azores ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

rwinners
not rated yet Jan 31, 2012
Talk about a science being in it's infancy... Look at Google Earth. One can see the interactions of plate tectonics. I seriously doubt that this has changed in millenia... er.. how does one express ... oh.. thousands of millenia.