Aftershock patterns and main shock faulting

We have compared aftershock patterns following several moderate to large earthquakes with the corresponding distributions of coseismic slip obtained from previous analyses of the recorded strong ground motion and teleseismic waveforms. Well-located aftershock hypocenters are projected onto the main shock fault plane, and their positions are examined relative to the zones of coseismic displacement indicated by the estimated distributions of main shock slip. We also examine the aftershock focal mechanisms, when these data are available, in an attempt to identify possible patterns of secondary faulting within the aftershock zone. Our results are consistent with a hypothesis of aftershock occurrence that requires a secondary redistribution of stress following primary failure on the earthquake fault. Aftershocks following the earthquakes examined in this study occur mostly outside of or near the edges of the source areas indicated by the patterns of main shock slip. The spatial distribution of aftershocks reflects either a continuation of slip in the outer regions of the areas of maximum coseismic displacement or the activation of subsidiary faults within the volume surrounding the boundaries of main shock rupture.

[1]  John G. Anderson.  A dislocation model for the Parkfield earthquake , 1974, Bulletin of the Seismological Society of America.

[2]  Michael Bevis,et al.  Patterns of seismicity associated with asperities in the central New Hebrides island arc , 1986 .

[3]  Donald V. Helmberger,et al.  The near-source ground motion of the 6 August 1979 Coyote Lake, California, earthquake , 1983 .

[4]  K. Rybicki.  Analysis of aftershocks on the basis of dislocation theory , 1973 .

[5]  D. Boore,et al.  Control of rupture by fault geometry during the 1966 parkfield earthquake , 1981 .

[6]  Interpretation of Near-Source Ground Motion and Implications , 1983 .

[7]  W. D. Richins,et al.  The 1983 Borah Peak, Idaho, earthquake and its aftershocks , 1987 .

[8]  Thomas H. Heaton,et al.  The 1971 San Fernando earthquake: A double event? , 1982 .

[9]  J. Booker.  Time dependent strain following faulting of a porous medium , 1974 .

[10]  T. Heaton,et al.  Generalized ray models of the San Fernando Earthquake , 1979 .

[11]  Thomas H. Heaton,et al.  RUPTURE HISTORY OF THE 1984 MORGAN HILL, CALIFORNIA, EARTHQUAKE FROM THE INVERSION OF STRONG MOTION RECORDS , 1986 .

[12]  K. Aki.  Characterization of barriers on an earthquake fault , 1979 .

[13]  R. Bucknam,et al.  Surface faulting accompanying the Borah Peak earthquake and segmentation of the lost river fault, central Idaho , 1987 .

[14]  K. Aki.  Seismic displacements near a fault , 1968 .

[15]  John Boatwright.  Characteristics of the aftershock sequence of the Borah Peak, Idaho, earthquake determined from digital recordings of the events , 1985 .

[16]  Ross S. Stein,et al.  The 1979 Homestead Valley Earthquake Sequence, California: Control of Aftershocks and Postseismic Deformation , 1983 .

[17]  W. Ellsworth,et al.  Aftershocks of the Coyote Lake, California, earthquake of August 6, 1979: A detailed study , 1982 .

[18]  F. E. Udwadia,et al.  Parkfield, California, earthquake of June 27, 1966: A three-dimensional moving dislocation , 1974, Bulletin of the Seismological Society of America.

[19]  C. Mendoza,et al.  Seismicity associated with the great Colombia-Ecuador earthquakes of 1942, 1958, and 1979: Implications for barrier models of earthquake rupture , 1984 .

[20]  Seena N. Hoose.  The Morgan Hill, California, earthquake of April 24, 1984 , 1987 .

[21]  Thomas H. Heaton,et al.  Inversion of strong ground motion and teleseismic waveform data for the fault rupture history of the 1979 Imperial Valley, California, earthquake , 1983 .

[22]  Christopher H. Scholz,et al.  Off-fault aftershock clusters caused by shear stress increase? , 1981 .

[23]  Aftershocks of an M = 4.2 earthquake in Hawaii and comparison with long-term studies of the same volume , 1985 .

[24]  J. Gu,et al.  Earthquake aftereffects and triggered seismic phenomena , 1983 .

[25]  S. K. Singh,et al.  Analysis of the Petatlan aftershocks: Numbers, energy release, and asperities , 1982 .

[26]  M. E. O'neill,et al.  Aftershocks of the 1966 Parkfield-Cholame, California, earthquake: A detailed study , 1970 .

[27]  C. R. Allen,et al.  The July 1986 North Palm Springs, California, Earthquake - The North Palm Springs, California, Earthquake Sequence of July 1986 , 1986 .

[28]  C. R. Allen,et al.  San Fernando Earthquake series, 1971: Focal mechanisms and tectonics , 1973 .

[29]  John W. Gephart,et al.  An improved method for determining the regional stress tensor using earthquake focal mechanism data: Application to the San Fernando Earthquake Sequence , 1984 .

[30]  Stephen H. Hartzell,et al.  INVERSION FOR SLIP DISTRIBUTION USING TELESEISMIC P WAVEFORMS: NORTH PALM SPRINGS, BORAH PEAK, AND MICHOACAN EARTHQUAKES , 1988 .

[31]  H. Kanamori,et al.  Depth of seismicity in the Imperial Valley Region (1977–1983) and its relationship to heat flow, crustal structure and the October 15, 1979, earthquake , 1986 .

[32]  J. Virieux,et al.  The evolution of the Gulf of Corinth (Greece): an aftershock study of the 1981 earthquakes , 1985 .

[33]  Paul Segall,et al.  Mechanics of discontinuous faults , 1980 .