No End Seen to China Quake Aftershocks

Another major earthquake in the making?

China Earthquake: Large Cluster of Powerful Shocks!

• Mainshock: 7.9 Magnitude – Monday, May 12, 2008 at 02:28:01 [time at epicenter]

• Latest aftershock: 5.5 Magnitude – Friday, May 16, 2008 at 01:25:48 PM [time at epicenter]

• Total number of major aftershocks: 59 [and continuing]

The last 4 aftershocks have strengthened in magnitude from 4.3 to 5.5 Mw. Is there another major shock in the making?

This map shows the predicted (theoretical) travel times, in minutes, of the compressional (P) wave from the earthquake location to points around the globe. The heavy black lines shown are the approximate distances to the P-wave shadow zone (103 to 140 degrees). (Caption: USGS)

Shadow zone

The shadow zone is the area of the earth from angular distances of 104 to 140 degrees from a given earthquake that does not receive any direct P waves. The shadow zone results from S waves being stopped entirely by the liquid core and P waves being bent (refracted) by the liquid core.

Did you know?

Through measuring how P and S waves travel through the earth and out the other side, a seismic wave shadow zone was discovered in about 1910. From the lack of S waves and a great slowing of the P wave velocity (by about 40%) it was deduced that the outer core is made of liquid. The shadow zone also defined the diameter of the core.

[If the outer core was not made of liquid, Earth could probably breakup into several pieces as a result of a v. large earthquake! FEWW]

Text and image: USGS.

How Many More Survivors?

The Clueless Wen Jiabao: “Most wide-spreading impact”

Chinese PM, Wen Jiabao, was quoted as saying that the 7.9-magnitude quake that hit southwestern Sichuan province on Monday had the “most wide-spreading impact” of any earthquake since the People’s Republic of China was founded in 1949, Xinhua news agency quoted Wen as saying.

[Note, for reasons unknown to FEWW moderators, the earthquake cluster’s mainshock was previously reported as magnitude 7.8, erroneously!]

The aftermath of a large earthquake cluster. (Credit: Reuters/Jason Lee) Image may be subject to copyright. See FEWW Fair Use Notice!

Related Links:

• Chinese Leaders Incapable of Handling Quake Aftermath

• China quake heaviest since 1949, says PM: state media
• China quake rescuers face huge hurdles
• Rumours fly as China quake victims seek news
• Dam cracks add to China quake fears
• China quake deaths estimated over 50,000 in Sichuan

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• China Quake Death Toll Nearly 10,000
• China Quake Kills 9,000
• China quake death toll nears 9,000

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