From: _http://tremor.nmt.edu/faq/how.html_ (http://tremor.nmt.edu/faq/how.html) " A wave one millimeter (1000 microns) high on a seismogram would have a magnitude of 3 because 1000 is ten raised to the third power. In contrast, a wave ten millimeters high would have a magnitude of 4. For reasons that we won't go into, a factor of 10 change in the wave height corresponds to a factor of 32 change in the amount of energy released during the earthquake. In other words, a magnitude 7 earthquake would produce seismogram waves 10 x 10 = 100 times as high and release energy 32 x 32 = 1024 times as great as a magnitude 5 earthquake. The Richter scale is open-ended, meaning there is no limit to how small or large an earthquake might be. Due to the nature of logarithms, it is even possible to have earthquakes with negative magnitudes, although they are so small that humans would never feel them. At the other end of the spectrum, there should never be an earthquake much above magnitude 9 on the Earth simply because it would require a fault larger than any on the planet. The largest earthquake ever recorded on Earth was a magnitude 9.5 that occurred in Chile in 1960, followed in size by the 1964 Good Friday earthquake in Alaska (magnitude 9.2), a magnitude 9.1 earthquake in Alaska during 1957, and a magnitude 9.0 earthquake in Russia during 1952. Two large earthquakes, one a magnitude 9.0 and one a magnitude 8.2, occurred on Dec. 26, 2004 and March 28, 2005, respectively, along the same fault zone off the coast of Sumatra, Indonesia." I hope that clears things up - but it may not. -William In a message dated 3/11/2011 8:24:08 A.M. Eastern Standard Time, hpi...@me.com writes:
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxx The energy release of an earthquake, which closely correlates to its destructive power, scales with the 3⁄2 power of the shaking amplitude. Thus, a difference in magnitude of 1.0 is equivalent to a factor of 31.6 ( = (101.0)(3 / 2)) in the energy released; a difference in magnitude of 2.0 is equivalent to a factor of 1000 ( = (102.0)(3 / 2) ) in the energy released. xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxx But in Japan there was a 7.2 quake two days ago, three shocks yesterday & 42 shocks today between 05:46 A.M. & 01:49 P.M. local Munich time, means 02:46 P.M. and 11:46 P.M. in Tokyo. But news did not talk about yesterdays heavy quake in Yuennan SW China with 25 dead & over 250 injured, but CCTV9 broadcasted the Japan disaster for several hours in their English program. Somebody out there to explain the above calculation in simplified words, please ? ############################################################################ ######################## Am 11.03.2011 um 13:49 schrieb William Gross: > This is a major disaster for Japan, with tsunami affecting the Philippines. > Warnings have gone out to Gaum, Hawaii, Indonesia and the US West Coast. > > Early reports have it as an 8.9, by comparision the Northridge EQ that his > the LA area in 1994 was a 6.7. This equake is about 100 times more > powerful. > > On Fri, Mar 11, 2011 at 6:25 AM, Lawrence Yates <yateslawre...@gmail.com>wrote: > >> I've just heard that the BBC Philharmonic Orchestra (based here in >> Mancheter) who are on tour in Japan at the moment are safe after the >> earthquake. Apparently they were going across a bridge in their coach when >> the earthquake struck. >> >> Lawrence >> >> >> >> -- >> Lawrenceyates.co.uk <http://lawrenceyates.co.uk/> >> _______________________________________________ >> post: horn@memphis.edu >> unsubscribe or set options at >> https://pegasus.memphis.edu/cgi-bin/mailman/options/horn/bgross%40airmail.net >> > _______________________________________________ > post: horn@memphis.edu > unsubscribe or set options at https://pegasus.memphis.edu/cgi-bin/mailman/options/horn/hpizka%40me.com _______________________________________________ post: horn@memphis.edu unsubscribe or set options at https://pegasus.memphis.edu/cgi-bin/mailman/options/horn/valkhorn%40aol.com _______________________________________________ post: horn@memphis.edu unsubscribe or set options at https://pegasus.memphis.edu/cgi-bin/mailman/options/horn/archive%40jab.org
