5.7 'Quake in Moçambique Channel on 24/09/2006

[Mefiante]

Apparently a Richter Magnitude 5.7 seismic event, i.e. a real teeth-rattler, in the Moçambique Channel occurred on Sunday, 24 September this year.  The main 'quake was followed by a series of smaller clustered aftershocks.

Anyone here feel anything?  Or even know something about the event?

I haven't read or heard a thing from any of various public media, but it is quite possible that I missed the reports.  The news comes from Dr 'Luthon64, a seismologist and my better half who is currently at Penn State University in the USA.  After locating and "sizing" the event, Dr 'Luthon64 is attempting to discern the seismic mechanism from earthquake data recorded at various stations around the globe (technically, a "moment tensor inversion" and "focal sphere radiation pattern").  If successful, this will shed much light on precisely how the 'quake started and developed, and possibly identify and/or clarify the nature of certain geological features in the area.  This in turn can lead to more exact earthquake hazard classification of the surrounding areas.

Worldwide seismic monitoring is primarily done in order to detect testing of nuclear weapons.  That such data can also help in elucidating the Earth's internal and crustal structures is a valuable spin-off.

I thought this might be of interest to some forum members.

'Luthon64

[qrios]

Didn't see anything in the news here either... just know 'bout the one in Feb...

http://www.mweb.co.za/news/?p=article&i=81820

[Mefiante]

Thanks for the link and the info.  The article reports that the February 'quake was measured at a Richter Magnitude of 7.3 to 7.5, and that a few people were injured and two killed.  The important things to remember about the Richter scale are (a) it is logarithmic, and (b) it gives an indication of the energy released in the seismic event.  The difference between a 5.7 and a 7.4 is that the energy released in the 7.4 is more than 160 times that of the 5.7, so it seems that the 5.7 was too small and/or far away to affect anyone severely and therefore wasn't worth reporting.  Another interesting fact is that at least one seismic event with a Richter Magnitude of 5.0 or more occurs somewhere on Earth every day.  A Magnitude 5.0 will flatten a house if the house is near the epicentre.

'Luthon64

[qrios]

Hi

The thing I find slightly upsetting, is that although we don't lie on the faultline, "There have been a string of seismic events along the Great Rift Valley, starting in Ethiopia then lately in Kenya,Goma in the DRC and now in Mocambique..."

Then again.. there HAS been a lot of seismic activity worldwide....

[Mefiante]

Well the Great Rift Valley is seismically active because Africa (more precisely, the African tectonic plate) is slowly being torn into two pieces along the Rift Valley (by the African plate's interaction with the Arabian and the Indian tectonic plates), starting in the north.  Like a piece of paper being torn, the major activity occurs at the point of tearing itself, and the Rift Valley's seismic activity moves south as the tearing progresses.  After a few more million years, the eastern part will be a completely separate landmass.  It'll be a while yet before the north-eastern areas of SA will be in any serious danger.  Also, seismic activity, though in a practical sense hard to predict accurately, is usually preceded by a range of warning signs.  It just requires sufficiently close monitoring coverage, which admittedly is at present a problem in Africa.

'Luthon64

[qrios]

Exactly why I plan on building my holiday house on  the West Coast soon...

Agree on the monitoring though....