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이정모,Margarita N. Luneva 한국지질과학협의회 2012 Geosciences Journal Vol.16 No.1
Wave amplitudes and amplitude ratios between different wave types carry information about variations of medium properties with depth and time. The most information is contained in the reflection and transmission coefficients, which depend on the physical properties of contacting media and boundary conditions. In this paper, the range of variations in reflection and transmission coefficients of plane waves generated at boundaries with different properties is examined. Numerical simulations of coefficients were carried out for the models of rigid and non-rigid contact between isotropic and anisotropic media. At the rigid contact between isotropic media, amplitudes of generated waves and their ratios vary within relatively narrow limits while the physical parameters of the media may accept various reasonable values. In anisotropic media, coefficients depend not only on the slowness contrast, but also on the wave polarization directions, which may vary considerably in space. Amplitude ratios of generated waves may vary significantly with the incident angle, and the amplitudes of converted waves may dominate or be comparable with monotype waves. Introducing non-rigid contact between media considerably broadens the range of coefficient variations. In contrast to the rigid contact, the incident energy goes predominantly into reflected and converted waves. The amplitude of converted waves may be relatively large and exceed the amplitudes of monotype and incident waves. In general, reflection and transmission coefficients generated at non-rigid contact depend on the values of stiffness coefficients and their ratio.
Shestakov, Nikolay V.,Takahashi, Hiroaki,Ohzono, Mako,Prytkov, Alexander S.,Bykov, Victor G.,Gerasimenko, Mikhail D.,Luneva, Margarita N.,Gerasimov, Grigory N.,Kolomiets, Andrey G.,Bormotov, Vladimir Elsevier 2012 Tectonophysics Vol.524 No.-
<P><B>Abstract</B></P><P>Small coseismic offsets detectable using GPS techniques were found more than 2300km away from the Great Tohoku 2011 earthquake epicenter. Area of the most intense far-field co- and postseismic deformations with the maximum offset values exceeding 40 and 18mm, respectively, extends westward from Honshu Island to the Korean Peninsula, northeastern China and southern Far East Russia. Sakhalin Island does not exhibit notable displacements caused by the earthquake, in contrast to the adjacent territories. A rectangular fault model with uniform slip was developed based on the GPS-detected far-field coseismic displacements using the spherically layered Earth assumption. Both far- and near-field coseismic deformations are generally well described by a single-segment rupture of 200×96km<SUP>2</SUP>, characterized by thrust slip with minor strike-slip component of about 33m and by the seismic moment value of 1.9·10<SUP>22</SUP>N·m (Mw=8.8), which roughly constrains the major slip area. The resultant compact fault geometry revealed that the main portion of the seismic moment had been realized in a relatively small-sized rupture segment. The sensitivity of far-field GPS data to the major slip area might also be used in the development of a seismically generated giant tsunami warning system.</P> <P><B>Highlights</B></P><P>► Coseismic jumps exceeding 40mm have been detected in the far-field zone. ► Postseismic displacements greater than 18mm have also been recorded. ► In general, a simple fault model adequately explains the observed coseismic offsets. ► The main part of the seismic moment was realized by a small rupture segment. ► The far-field GPS data can be used in the development of a giant tsunami warning system.</P>