Open AccessOn the nature of regional seismic phases–II. On the influence of structural barriers
Author(s) -
Furumura T.,
Kennett B. L. N.
Publication year - 1997
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.1997.tb01577.x
Subject(s) - graben , geology , attenuation , seismogram , seismology , geophysics , seismic energy , scattering , refraction , sedimentary rock , seismic wave , tectonics , paleontology , optics , physics
Summary The blockage of the L g wave by crustal barriers such as continental margins and graben structures has long been recognized as providing a very useful tool for mapping large‐scale lateral crustal variations along the propagation path. Numerical simulation of L g ‐wave propagation in complex anelastic media using the pseudospectral method provides insight into the nature of the propagation process using both snapshots of the wavefield and synthetic seismograms. A variety of 2‐D structures have been investigated, including the influence of sediments, crustal thickness and attenuation. Thick sedimentary basins covering a graben structure can have a major influence, since they remove L g energy by generating P conversion and scattering–the principal mechanisms for strong L g attenuation across a graben. The reduction of the L g energy is reinforced by anelastic attenuation in the sediments as well as the influence of the gradually thinning crustal waveguide associated with an elevated Moho. The extinction of L g in a sequence of explosions fired across the central graben of the North Sea can be simulated by numerical calculations for the structure derived from refraction experiments.