1. Effects of Rotation Motions on a Seismogram Hung-Chie Chiu Institute of Earth Sciences, Academia Sinica, Taiwan March 19, 2014

2. Outline What is rotational motion? Should we consider the rotation motions and Its effects In seismological analyses? Effects of rotational motions Conclusions

3. Translational & Rotational Motions

4. Infinitesimal Strain and Rotations Strain Rotation

5. VSE-355 G3 Velocity-type strong-motion sensor R1 Rotation Sensor 6-channel, 24-bit Quanterra Q330 data logger 100sps Continue recording

6. 20091219 ML6.920120226 ML6.4

7. Consider a transversely polarized plane wave

8. PRR-PGA at HWLB

9. Effects of Rotational motions 1.Effects of Centrifugal acceleration 2.Effects of gravity 3.Effects of rotational frame 1 2 3

10. 20091219 ML6.9

11. Gravity Effects

12. Effects of Rotational Motions on Waveforms ~10% ~0.01%

16. PRR-PGA at HWLB

17. 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

18. Effects of Gravity All three components fit the Quadratic polynomials in the log-log scale Vertical component are much smaller than the horizontal components

20. ?

21. 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.