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School Seismology :: Blog :: M7.2 earthquake in China

March 21, 2008


Paul Denton @ School Seismology

M7.2 earthquake in China

At 22:33 last night (20th March) there was a M7.2 event in China.  My initial reaction to seeing the email was mixed... China is the location of the worlds most devasting earthquakes.   Fortunately this event happend in a sparsley populated region in Xinjiang province and no reports of casualties have been posted.

Stations KEYW and PAUL (whose data is is uploaded automatically to the IRIS ftp site) both recorded this event very well (it is about 58 degrees away from the UK).  On station KEYW you can clearly see arrivals for P(22:43) PP(22:45) S(22:51) SS(22:55) and Surface waves  (23:00-23:30)

0803202232keyw.sac

Keywords: 20mar2008, china, earthquake, event, keyw, paul

Posted by Paul Denton @ School Seismology

Comments

  1. I was just checking my e-mails last night when the earthquake alert came through , i checked the trace on PAUL and the 22 hor log was there, the trace of the event showed quite clearly, didn't really need filtering, thought I'll check that in the morning .......the trace now displayed is not as clear as the earlier trace is this because of the aftershocks at 22:50 5.3, 23;12 5.5 ?? I notice there has been a series of other aftershocks today of about level 5,  00;20, 04:03 and 06:16. moral being..."don't put of till tomorrow.....

     

    Pete Hill

     Paulet

    Pete Hill on Friday, 21 March 2008, 15:31 GMT # |

  2. I managed to look at the PAUL trace this morning (because it is automatically uploaded to IRIS ftp site).   Everything you see from 22:40 to midnight is signal from the 22:33 M7.2 event.    The surface waves in particular spread out with the whole extended wavetrain being caused by the original event (technically the extended wavetrain is called the "coda" and is caused partly by multipathing ... waves travelling different routes to get to the same end point and also dispersion .. where wave components of different frequencies travel at different speeds with the longest wavelngths travelling fastest)

    Paul Denton on Friday, 21 March 2008, 16:36 GMT # |

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