Aftershock zones of large shallow earthquakes: fault dimensions, aftershock area expansion and scaling relations

Abstract

SUMMARY We determine the aftershock areas from relocated hypocentres for 64 dip‐slip and eight strike‐slip earthquakes in the period 1977–1996 together with those for three recent earthquakes, the 1998 Antarctic plate earthquake, the 1999 Izmit, Turkey earthquake and the 2000 Wharton Basin earthquake. We also include the data for 27 strike‐slip earthquakes from Pegler & Das (1996). We find that the location of the hypocentre is essentially random along strike for both strike‐slip and dip‐slip earthquakes. Subduction zone earthquakes appear to initiate more frequently towards the down‐dip edge of the fault, whereas the non‐subduction zone dip‐slip earthquakes do not have any preferred depth of initiation. The aftershock zones of subduction zone earthquakes often expand substantially along strike and up dip but far less in the down‐dip direction, whereas those for non‐subduction zone earthquakes do not expand significantly in either the up‐ or the down‐dip direction. Subduction zone thrust earthquakes have larger and more numerous aftershocks than earthquakes in all other tectonic settings. For strike‐slip earthquakes, we find that slip increases at least linearly with length. For dip‐slip earthquakes, we find that the ratio of length to width increases systematically with length for lengths >40 km, indicating that there is some restriction on fault width; slip is found to be proportional to length over the moment range 1017 N m <M0<3×1021 N m, taking our data in conjunction with the data of Wells & Coppersmith (1994).

Estimation of successive coseismic vertical offsets using coeval sedimentary events – application to the southwestern limit of the Sea of Marmara's Central Basin (North Anatolian Fault)

“…The results show M w comprised between 5.9 and 6.6. The corresponding M O (seismic moment) values, the fault length and the fault surface values, were plotted on two diagrams respectively from Kanamori and Anderson (1975) and Henry and Das (2001). Our results fit better with intraplate earthquake distributions and using a 8 km rupture length (thus the whole SW limit of the inner Central Basin).…”

Global Relations Between Seismic Fault Parameters and Moment Magnitude of Earthquakes

“…Such data have been produced by many researchers all over the world and have been summarized and published recently in certain scientific papers (Wells & Coppersmith 1994, Pegler & Das 1995, Fujii & Matsu'ura 2000, Henry & Das 2001, Kagan 2002, Papazachos & Papazachou 2003. The values of the fault length, L, and of the fault areas, S, which are sited in these papers and for which reliable moment magnitudes, M, are available, are used in the present work.…”

Empirical Relationships between Aftershock Zone Dimensions and Moment Magnitudes for Plate Boundary Earthquakes in Taiwan

“…Over the past several decades, the empirical relationships between seismic moment (M 0 ) or moment magnitude (M w ) and various earthquake faulting parameters (e.g., rupture length, width, and displacement) have been studied by a number of researchers on the basis of worldwide data sets (e.g., Scholz, 1982;Bonilla et al, 1984;Scholz et al, 1986;Romanowicz, 1992;Wells and Coppersmith, 1994;Pegler and Das, 1996;Wang and Ou, 1998;Mai and Beroza, 2000;Stock and Smith, 2000;Henry and Das, 2001;Bakun, 2002, 2008;Kagan, 2002;Manighetti et al, 2007;Blaser et al, 2010;Leonard, 2010;Strasser et al, 2010) and regional data (e.g., Dowrick and Rhoades, 2004;Konstantinoua et al, 2005;Murotani et al, 2008;Yen and Ma, 2011). These scaling relationships provide not only useful empirical relationships for practical seismic hazard analyses but also perspective on earthquake physics (Shaw, 2009).…”