Comparison of Earthquake Location by Using One- and Three- Dimensional Velocity Structures in the Taiwan Area

台灣地區利用一維與三維速度構造地震定位之比較研究

陳朝輝(Chau-Huei Chen) ； 顏宏元(Horng-Yuan Yen) ； 葉義雄(Yih-Hsiung Yeh)

《Terrestrial, Atmospheric and Oceanic Sciences》 6卷4期 (1995/12) Pp. 527-540

並列摘要

Many approaches for locating earthquakes attempt to solve a nonlinear inverse system in a one-dimensional velocity model. To ensure precise earthquake locations in geologically complex areas, however, a three-dimensional velocity model has to be considered. In this study, the authors have applied an alternative approximate method based on the dynamic ray theory with a 3-D velocity model to relocate 374 events from 1980 to 1989 recorded by the Taiwan Telemetered Seismographic Network (TTSN). The solutions to locating earthquakes using 1-D and 3-D velocity models are compared. These results show that the root mean square (RMS) of travel time residuals for the 3-D model are much lower than those for the 1-D velocity model. The discrepancies between the 1-D and 3-D solutions reflect the importance of lateral velocity variations in locating earthquakes in the Taiwan area. These discrepancies are larger in focal depths than in epicentral determinations. From the examination of seismicity along the Chaochou fault with both 1-D and 3-D velocity models, the results here show that the hypocenter determinations from a 1-D model may even lead to an absurd interpretation in seismicity. The presence of the lateral heterogeity of seismic velocity in Taiwan makes the necessity of locating earthquakes with a three-dimensional velocity model. The increases in computation time in using a 3-D velocity model to locate earthquaks can be minimized by applying the dynamic ray tracing technique due to its fast computation capacity and high level of accuracy.

並列關鍵字

Earthquake location ； Velocity structure ； TTSN