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Effects of Rotation Motions on a Seismogram. Hung-Chie Chiu Institute of Earth Sciences, Academia Sinica, Taiwan March 19, 2014. Outline What is rotational motion? Should we consider the rotation motions and Its effects In seismological analyses? Effects of rotational motions
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Effects of Rotation Motions on a Seismogram Hung-Chie Chiu Institute of Earth Sciences, Academia Sinica, Taiwan March 19, 2014
Outline • What is rotational motion? • Should we consider the rotation motions and Its effects In seismological analyses? • Effects of rotational motions • Conclusions
Infinitesimal Strain and Rotations Strain Rotation
VSE-355 G3 Velocity-type strong-motion sensor R1 Rotation Sensor 6-channel, 24-bit Quanterra Q330 data logger 100sps Continue recording
20091219 ML6.9 20120226 ML6.4
Effects of Rotational motions • Effects of Centrifugal acceleration • Effects of gravity • Effects of rotational frame 2 1 3
Effects of Rotational Motionson Waveforms ~0.01% ~10%
Effects of Centrifugal Acceleration • All three components fit the quadratic polynomials very well in the log-log scale • The vertical component is about one order magnitude smaller than that of the horizontal components
Effects of Gravity • All three components fit the Quadratic polynomials in the log-log scale • Vertical component are much smaller than the horizontal components
Conclusions • Rotation motions always accompany with translational motions • The effects of rotation motions include: (1) Centrifugal acceleration, (2) Gravity effects, (3) Effects of rotation frame. • Effects of rotational motions rapidly grow up with ground motions and these effects can not be ignored in near-fault and/or extremely large ground motions.