HR: 15:10h
AN: S13F-07    [Abstracts]
TI: The Role of Shear and Interface Waves in the Excitation of T-waves
AU: * Odom, R I
EM: odom@apl.washington.edu
AF: Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, WA 98105,
AU: * Odom, R I
EM: odom@apl.washington.edu
AF: Department of Earth and Space Science, University of Washington, Box 351310, Seattle, WA 98195,
AB: T-waves are late arriving phases on a seismogram which travel a significant portion of their journey from the source to the receiver along a slow oceanic path. Park, Soukup and Odom [2001] proposed a modal scattering mechanism which permits energy from steeply arriving rays impinging on the ocean bottom to be converted to shallow grazing angle rays corresponding to low order modes known to comprise the T-wave signal. The Scholte interface waves are crucial to this energy transfer as they have anti-nodes nearly coincident with the ocean bottom. Any seafloor roughness acts as a secondary source located right on the Scholte wave anti-node. This allows energy to be efficiently transferred from high energy modes to lower energy, and slower, T-wave modes. In fact the presence of the Scholte waves is crucial to the existence of T-waves. Some finite shear strength in the bottom sediments and/or upper ocean crust is essential for the existence of the Scholte waves. Elastic interface waves do not exist the boundary between two fluids. The effect of the the shear modulus of the ocean bottom sediment and ocean crust on the excitation of the interface waves and T-waves is discussed.
DE: 3025 Marine seismics (0935, 7294)
DE: 3285 Wave propagation (0689, 2487, 4275, 4455, 6934)
DE: 4259 Ocean acoustics
DE: 7260 Theory
DE: 7290 Computational seismology
SC: Seismology [S]
MN: 2007 Fall Meeting