수리지질학/지구화학/지구물리학․
10월 28일(금)2005 대한지질학회 추계학술발표회 초록집
49Determining hypocentral parameters of local earthquakes using weighting factor based on take-off angle and
two-point ray tracing
Inkyeong Hahm1,*․ Woohan Kim1․ Jungmo Lee2․ Jeongsoo Jeon3․Jongchan Park4
1Gyeongsang National University, [email protected]
2Kyungpook National University
3Korea Institute of Geoscience and Mineral Resources
4Korea Meteorological Administration
This paper introduces an improved method of determining the hypocentral parameters of local earthquakes by applying a weighting factor based on the take-off angle at the source. The hypocentral parameters estimated by the existing methods contain errors if the true velocity structure is not used, and they are not identical depending on the initial velocity models. Variation in the travel time caused by focal depth may indicate the degree of focal depth information contained in the data, as the degree of information will de- crease rapidly as the epicentral distance increases. The take-off angle at the source is re- lated to the epicentral distance. Therefore, a weighting factor representing the degree of focal depth information could be described in terms of the take-off angle at the source.
The accuracy of hypocentral parameters, especially focal depth and origin time, was im- proved by applying the take-off angle as the weighting factor and two-point ray tracing to the existing methods. Synthetic travel time data both with noise and without noise were generated using two-point ray tracing in a model in which velocity structure and hypo- central parameters are known. We then examined the effect of the weighting factor by comparing the estimated hypocentral parameters with the true, known values. The com- putational results show that the focal depth and the origin time estimated by the im- proved method (MHYPO) in this study are more accurate than those estimated by the ex- isting method. The MHYPO determines the hypocentral parameters accurately and stably, although the used velocity model was different from the true velocity model and the data had noise.
3-12 구두
