The new inversion algorithm developed based on the recent progress in thenonlinear programming study by us is used to invert the earthquake source process of Chi Chiearthquake M_w7.6, 20 Semptember,1999, Taiwan. A cur...The new inversion algorithm developed based on the recent progress in thenonlinear programming study by us is used to invert the earthquake source process of Chi Chiearthquake M_w7.6, 20 Semptember,1999, Taiwan. A curve fault model is constructed in our inversionto make the fault model close to the real rupturing fault to reduce the influence from thediscrepancy between the constructed fault model and the real rupturing fault. The results show that(1) the rupture process of the Chi Chi earthquake source lasted about 32 seconds and the mainfaulting occurred between 6th to 21st second after the start of the ruptures and the high slip areawere mainly located at the northern segment of the fault. (2) The slip was dominated by thrustfaulting. The average rake angle was 64.5°, which was very consistent with those inverted by USGS,Harvard and CWB (Central Weather Bureau of Taiwan). The amount of the moment inverted in this paperwas 7.76x10^(20) NM, which was a slightly bigger than those inverted by USGS and Harvard. (3) Aclear nucleation step existed in the source faulting process and it lasted about 6 seconds. Themoment release rate accelerated obviously at the end of the nucleation step. The faulting startedfrom the southern segment and mainly occurred at the northern segment after 10 seconds. At the endof this paper, we analyzed the reliability of the inversion result via comparing with the GPSobservations and discussed its scientific signification.展开更多
Inversion for the seismic fault rupture history is an important way to study the nature of the earthquake source. Inthis paper, we have selected two Taiwan earthquakes that occurred closely in time and located in the ...Inversion for the seismic fault rupture history is an important way to study the nature of the earthquake source. Inthis paper, we have selected two Taiwan earthquakes that occurred closely in time and located in the same region,inversed the distribution of the slip amplitudes, rakes, risetimes and the rupture times on the fault planes by usingGDSN broad-band and long-period records and the adaptive hybrid global search algorithm, and compared the twoevents. The slip rate of every subfault calculated provides information about the distribution of tectonic stress andfault strength. To the former event (Ms=6.0), the maximum slip amplitude 2.4 m and the minimum risetime 1.2 sare both located at the hypocentre. The latter earthquake (Ms=6.6) consisted of two subevents and the second source has 4 s delay. The maximum slip amplitUde 0.9 m located near hypocentre is corresponding to the minimumrisetime l.4 s, and the corresponding maximum slip rate 0.7 m.s~-1 is similar to the peak value of other large sliprate areas. We consider that the latter event has more complicated temporal-spatial distribution than the former.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.40134010)the National Basic Research Program of China(Grant No.2004CB41804).
文摘The new inversion algorithm developed based on the recent progress in thenonlinear programming study by us is used to invert the earthquake source process of Chi Chiearthquake M_w7.6, 20 Semptember,1999, Taiwan. A curve fault model is constructed in our inversionto make the fault model close to the real rupturing fault to reduce the influence from thediscrepancy between the constructed fault model and the real rupturing fault. The results show that(1) the rupture process of the Chi Chi earthquake source lasted about 32 seconds and the mainfaulting occurred between 6th to 21st second after the start of the ruptures and the high slip areawere mainly located at the northern segment of the fault. (2) The slip was dominated by thrustfaulting. The average rake angle was 64.5°, which was very consistent with those inverted by USGS,Harvard and CWB (Central Weather Bureau of Taiwan). The amount of the moment inverted in this paperwas 7.76x10^(20) NM, which was a slightly bigger than those inverted by USGS and Harvard. (3) Aclear nucleation step existed in the source faulting process and it lasted about 6 seconds. Themoment release rate accelerated obviously at the end of the nucleation step. The faulting startedfrom the southern segment and mainly occurred at the northern segment after 10 seconds. At the endof this paper, we analyzed the reliability of the inversion result via comparing with the GPSobservations and discussed its scientific signification.
文摘Inversion for the seismic fault rupture history is an important way to study the nature of the earthquake source. Inthis paper, we have selected two Taiwan earthquakes that occurred closely in time and located in the same region,inversed the distribution of the slip amplitudes, rakes, risetimes and the rupture times on the fault planes by usingGDSN broad-band and long-period records and the adaptive hybrid global search algorithm, and compared the twoevents. The slip rate of every subfault calculated provides information about the distribution of tectonic stress andfault strength. To the former event (Ms=6.0), the maximum slip amplitude 2.4 m and the minimum risetime 1.2 sare both located at the hypocentre. The latter earthquake (Ms=6.6) consisted of two subevents and the second source has 4 s delay. The maximum slip amplitUde 0.9 m located near hypocentre is corresponding to the minimumrisetime l.4 s, and the corresponding maximum slip rate 0.7 m.s~-1 is similar to the peak value of other large sliprate areas. We consider that the latter event has more complicated temporal-spatial distribution than the former.
