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IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS011 Oral Presentation 2122
Strain rate field calculated from GPS measurements in Chinese Continent
Dr. Shoubiao Zhu
Geophysics Institute of Crustal Dynamics, CEA IASPEI
Yongen Cai, Yaolin Shi
In previous studies, the strain rate in China has been computed from GPS measurements using different
methods, resulting in quite different estimates of the strain rate. In this study, we use the kriging
method to interpolate the scattered GPS velocity data to grid values, and then calculate the strain rate
for each volume element, using a method similar to the derivation of shape functions in the finite
element algorithm. We found that this approach can provide an accurate and stable strain rate field for
the Chinese continent. The result shows that the orientations of principal strain rates are consistent with
those of the P axis and T axis of focal mechanisms. The distribution of maximum shear strain rate
clearly delineates some major active fault zones surrounding the Tibetan Plateau. The maximum shear
strain rate is comparable with that obtained from the analysis of seismic moment release. In part of the
Tibetan plateau, containing normal faults and pull-apart grabens, we obtain an extensional state of
strain. The absolute value of the strain rate in the west of China is approximately 5 times larger than
that of the east China, and the pattern of the strain rate field in most of the Chinese continent is
controlled by the India/Eurasia collision.
Keywords: strain rate field, gps measurements, chinese continent