Open AccessThe Largest Earthquakes We Should Prepare for
Author(s) -
Toru Matsuzawa
Publication year - 2014
Publication title -
journal of disaster research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.332
H-Index - 18
eISSN - 1883-8030
pISSN - 1881-2473
DOI - 10.20965/jdr.2014.p0248
Subject(s) - seismology , geology , quake (natural phenomenon) , moment magnitude scale , magnitude (astronomy) , seismic moment , earthquake magnitude , remotely triggered earthquakes , interplate earthquake , slip (aerodynamics) , seismic gap , earthquake swarm , plate tectonics , tsunami earthquake , foreshock , aftershock , induced seismicity , fault (geology) , tectonics , geometry , physics , mathematics , astronomy , scaling , thermodynamics
We should estimate the size of the largest earthquakes carefully to minimize future earthquake losses. Taking the earth’s size and the thickness of the lithosphere into account, the largest earthquakes are estimated to have a magnitude ( M ) of 11. The occurrence of such a gigantic earthquake, however, could wipe out the human race because energy from an M 11 earthquake would be as large as the asteroid impact that is thought to have caused the extinction of the dinosaurs. This would make it meaningless to prepare for M 11 earthquakes. It would be more realistic to calculate the seismic moment expected from the longest plate boundary, i.e., from the northern to northwestern boundary of the Pacific plate. The plate boundary is about 10,100 km long and the magnitude of an earthquake occurring there is estimated at approximately 10, assuming that the fault is 200 kmwide and average slip is 20 m. This means that M 10 events would be the largest earthquakes we could estimate as occurring. It will not be pragmatic, however, to attempt to devise measures against such extremely rare events. It is nonetheless important to numerically simulate beforehand what might happen during such events to quickly and accurately determine the initial response to quake shaking and tsunamis.