Open AccessA note on the surface volume change of shallow earthquakes
Author(s) -
Ward Steven N.
Publication year - 1986
Publication title -
geophysical journal of the royal astronomical society
Language(s) - English
Resource type - Journals
eISSN - 1365-246X
pISSN - 0016-8009
DOI - 10.1111/j.1365-246x.1986.tb04524.x
Subject(s) - slip (aerodynamics) , geology , magnitude (astronomy) , geodesy , earthquake magnitude , seismology , moment magnitude scale , volume (thermodynamics) , poisson distribution , maximum magnitude , surface (topology) , geometry , mathematics , physics , induced seismicity , thermodynamics , statistics , astronomy , scaling
Summary. This note presents an exact analytical formula for determining the magnitude of coseismic surface volume change (δ V ) of earthquake faults in a half‐space. For a Poisson solid, the formula is remarkably simple; δ V = M zz |8μ, where M zz is one of the moment tensor elements of the source. Maximum δ V values derive from dip slip on faults plunging 45°. For these events, surface volume changes of 0.0001 and 4.3 km 3 can be expected for magnitude 5 and 8 earthquakes respectively. All of the coseismic surface volume change is recovered in the interseismic period through relaxation of the Earth and rebound of the surface. A useful rule of thumb for estimating the magnitude of vertical rebound in 45° dip slip events is δ h p =Δ s /24, where Δ s is the coseismic slip on the fault.