Possible splay fault slip during the 1946 Nankai earthquake

This paper considers seafloor deformation associated with the 1946 Nankai earthquake, which occurred in the Nankai Trough subduction zone off the coast of southwest Japan. We note that recent high-resolution determinations of the slip distribution, assumed to be confined to the plate boundary, result in a pronounced maximum in seafloor displacement midway between the coast of Shikoku and the trough axis. We show that this feature could be due to slip on a splay fault rather than the plate boundary. Such a model for the western part of the slip distribution is able to account for the main features of the tsunamigenic seafloor deformation obtained in previous studies, with a maximum slip consistent with the plate convergent rate and history of earthquake recurrence at the Nankai Trough.

[1]  G. Massoth,et al.  Oregon Subduction Zone: Venting, Fauna, and Carbonates , 1986, Science.

[2]  T. Sagiya,et al.  Coseismic slip resolution along a plate boundary megathrust: The Nankai Trough, southwest Japan , 1999 .

[3]  K. Miyashita.  A MODEL OF PLATE CONVERGENCE IN SOUTHWEST JAPAN, INFERRED FROM LEVELING DATA ASSOCIATED WITH THE 1946 NANKAIDO EARTHQUAKE , 1987 .

[4]  J. C. Savage.  A dislocation model of strain accumulation and release at a subduction zone , 1983 .

[5]  Walter H. F. Smith,et al.  Free software helps map and display data , 1991 .

[6]  M. Ando.  Source mechanisms and tectonic significance of historical earthquakes along the nankai trough, Japan , 1975 .

[7]  G. Plafker,et al.  Alaskan Earthquake of 1964 and Chilean Earthquake of 1960: Implications for Arc Tectonics , 1972 .

[8]  M. Ando.  A fault model of the 1946 Nankaido earthquake derived from tsunami data , 1982 .

[9]  K. Satake,et al.  Coseismic slip distribution of the 1946 Nankai earthquake and aseismic slips caused by the earthquake , 2001 .

[10]  S. Stein,et al.  A model for the motion of the Philippine Sea Plate consistent with NUVEL‐1 and geological data , 1993 .

[11]  Kelin Wang,et al.  The updip and downdip limits to great subduction earthquakes: Thermal and structural models of Casca , 1999 .

[12]  Kelin Wang,et al.  Thermal constraints on the zone of major thrust earthquake failure: The Cascadia Subduction Zone , 1993 .

[13]  H. Kanamori.  Tectonic implications of the 1944 Tonankai and the 1946 Nankaido earthquakes , 1972 .

[14]  W. Thatcher.  The earthquake deformation cycle at the Nankai Trough, southwest Japan , 1984 .

[15]  Y. Fukao.  Tsunami earthquakes and subduction processes near deep-sea trenches , 1979 .

[16]  N. Takahashi,et al.  Western Nankai Trough seismogenic zone: Results from a wide‐angle ocean bottom seismic survey , 2000 .

[17]  K. Satake.  Depth distribution of coseismic slip along the Nankai Trough, Japan, from joint inversion of geodetic and tsunami data , 1993 .

[18]  Kenji Satake,et al.  The 1964 Prince William Sound earthquake: Joint inversion of tsunami and geodetic data , 1996 .

[19]  Y. Okada.  Surface deformation due to shear and tensile faults in a half-space , 1985 .

[20]  M. Langseth,et al.  Fluids in accretionary prisms , 1990 .