Well I believe the reason for this is because a direct measure of energy doesn't exactly relate to how that energy is released. A good case in point involves thermonuclear exchange. I personally hope it never happens, but it was a brief hobby of mine a few years ago to study how the bomb was developed, how it worked, and what our arsenals meant for 'humanity'. It was very eye opening to learn these things. It's a common misconception that if it full exchange were to happen that there would be one large strike for each major city, but the truth is the US and USSR Arsenals numbered in the tens of thousands because they found out that there would be much more damage from a 'swarm' of lesser yield weapons than one large one. Additionally, they found out that there would be more damage from an explosion in the air rather than on the ground. Earthquakes work the same way I suppose. Energy released is pretty much a direct measurement, but how it translates into what damage it causes depends highly on how much energy is transferred to the surface, or if there is soil liquefaction, or a resulting tsunami, the resultant ground acceleration, etc. -William In a message dated 3/11/2011 3:27:46 P.M. Eastern Standard Time, william.s.gr...@gmail.com writes:
It is probably a good tool for geophysical purposes but problematic in the disaster response business, case in point Christchurch. It would nice to have something that indicates scope of damage. On Mar 11, 2011, at 12:59 PM, Jeffrey S Barker <jbar...@binghamton.edu> wrote: > Earthquake magnitude is determined from the amplitude of ground motion as > measured on a seismograph. In principle, energy should be proportional to > amplitude squared, just as sound intensity is proportional to pressure > squared. However, Richter noted that the energy released by an earthquake > does not simply scale up. A larger earthquake ruptures a larger fault, over > a larger range of depths, and over a longer time duration. So, in defining > the magnitude scale, Richter empirically related magnitude to energy > according to: log E = 11.4 + 1.5 M (for energy in ergs). Thus, for every > increase in magnitude by 1 unit, energy increases by 10^(1.5), or a facor of > 31.6. > > Jeff Barker > (seismologist and horn player) > >> >> Date: Fri, 11 Mar 2011 14:22:51 +0100 >> From: Hans Pizka <hpi...@me.com> >> Subject: Re: [Hornlist] BBC Phil in Japan >> To: The Horn List <horn@memphis.edu> >> Message-ID: <fba8fab4-5328-45cd-9595-e10842bec...@me.com> >> Content-Type: text/plain; charset=utf-8 >> >> >> xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx >> 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. >> >> xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx >> 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 >> >> > > -- > Jeffrey S. Barker > Assoc. Prof. of Geophysics, Binghamton University > Faculty Master, Dickinson Community > (607) 777-2522 (Geology) (607) 777-2826 (Dickinson) > http://bingweb.binghamton.edu/~jbarker/ > _______________________________________________ > 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/valkhorn%40aol.com _______________________________________________ post: horn@memphis.edu unsubscribe or set options at https://pegasus.memphis.edu/cgi-bin/mailman/options/horn/archive%40jab.org
