HR: 11:20h
AN: S31H-05    [PDF]
TI: Teleseismic imaging of upper mantle structures around the Taiwan area
AU: * Lin, P
EM: PeiYeng_lin@escc.gep.ncu.edu.tw
AF: The Institute of Oceanography National Taiwan University, Taiwan, ROC, No.1, Sec. 4, Roosevelt Road, Taipei, Taiwan, Taipei, 106 Taiwan
AU: Huang, B
EM: hwbs@earth.sinica.edu.tw
AF: The Institute of Earth Science Academia Sinica, Taiwan, ROC, 128,Academia Road Sec. 2, Nankang, Taipei, Taiwan, ROC, Taipei, 115 Taiwan
AU: Chiao, L
EM: chiao@ntu.edu.tw
AF: The Institute of Oceanography National Taiwan University, Taiwan, ROC, No.1, Sec. 4, Roosevelt Road, Taipei, Taiwan, Taipei, 106 Taiwan
AB: Teleseismic events that had been clearly recorded across TTSN and CWBSN through the past 7 years (1987-1995) has been identified and compiled. Recorded waveforms of those with epicentral distances 30$\deg$~90$\deg$ away from Taiwan are analyzed by the multi-channel cross correlation algorithm to yield a set of consistent relative differential travel times across the area covered by the seismic networks. After careful quality control, 140 events that yield relative differential travel times within the range of 1.5 seconds across the area are retained. These events compose about 2455 rays going through the upper mantle around the Taiwan region. Tomographic inversion of these travel-time residuals are undertaken by assuming that the heterogeneities of the velocity structure of the target area, within 20.5$\deg$-26.5$\deg$ N, 118$\deg$-124$\deg$E and with the depth above 400 km, is responsible for causing the relative differential travel times. Preliminary model structures obtained from three different inversion strategies, including the damped least squares, the convolutional quelling regularization and the multiscale parameterization, are cross-analyzed to probe for the possible upper mantle structure. Although the data seems to be noisy and the ray coverage is very likely too sparse, there are still some interesting implications for upper mantle structures underneath the Taiwan area. We will discuss some of these preliminary results as well as proposing for directions of future study.
DE: 3260 Inverse theory
DE: 7218 Lithosphere and upper mantle
DE: 8180 Tomography
SC: Seismology [S]
MN: 2003 Fall Meeting