No abstract

No abstract

No abstract

Rotational motions generated by large earthquakes in the far field have been successfully measured, and observations agree well with the classical elasticity theory. However, recent rotational measurements in the near field of earthquakes in Japan and in Taiwan indicate that rotational ground motions are 10 to 100 times larger than expected from the classical elasticity theory. The near-field strong-motion records of the 1999 M w 7:6 Chi-Chi, Taiwan, earthquake suggest that the ground motions along the 100 km rupture are complex. Some rather arbitrary baseline corrections are necessary in order to obtain reasonable displacement values from double integration of the acceleration data. Because rotational motions can contaminate acceleration observations due to the induced perturbation of the Earth's gravitational field, we started a modest program to observe rotational ground motions in Taiwan. Three papers have reported the rotational observations in Taiwan: (1) at the HGSD station (Liu et al., 2009), (2) at the N3 site from two TAiwan Integrated GEodynamics Research (TAIGER) explosions (Lin et al., 2009), and (3) at the Taiwan campus of the National Chung-Cheng University (NCCU) (Wu et al., 2009). In addition, Langston et al. (2009) reported the results of analyzing the TAIGER explosion data. As noted by several authors before, we found a linear relationship between peak rotational rate (PRR in mrad=sec) and peak ground acceleration (PGA in m=sec 2) from local earthquakes in Taiwan, PRR 0:002 1:301 PGA, with a correlation coefficient of 0.988.

We studied the interaction between hydrogen and point defects generated by electron irradiation of Si by means of optical absorption measurement. Specimens were prepared from n-type Si crystals. Those specimens were doped with hydrogen by annealing in a hydrogen atmosphere at 1200 • C followed by quenching and were subsequently irradiated with 3 MV electrons at room temperature. We observed their optical absorption spectra at about 6 K with a resolution of 0.25 cm −1 . Many optical absorption peaks were observed in electron-irradiated specimens. Most of those peaks disappeared at around 300 • C due to isochronal annealing. On the other hand, new optical absorption lines appeared at 2223 cm −1 and 2166 cm −1 after annealing at high temperature, namely above 150 • C. The former is known to be due to a complex of one self-interstitial atom and 4 hydrogen atoms. We propose that the 2166 cm −1 peak is due to a complex of one self-interstitial atom and three hydrogen atoms. These results clearly show that complexes of self-interstitials exist after electron-irradiation of Si and they dissociate above 150 • C.