摘要
Using over 3 500 first P arrival times recorded by nine digital seismic stations from Hainan Digital Seismic Net-work during 1999～2005,a 3-D P-wave velocity model of the crust under Hainan Island and adjacent regions has been determined. The results show that the pattern of velocity anomalies in the shallower upper crust is somewhat associated with the surface geological tectonics in the region. A relative low-velocity anomaly appears north of the Wangwu-Wenjiao fault zone and a relative high-velocity anomaly appears south of the Wangwu-Wenjiao fault zone,corresponding to the depressed areas in north Hainan Island,where many volcanoes are frequently active and geothermal values are relatively higher,and the uplifted and stable regions in central and south of the Hainan Is-land. In the middle and lower crust velocities are relatively lower in east Hainan than those in west Hainan,possi-bly suggesting the existence of the upwelling of hot materials from the mantle in east Hainan. The pattern of veloc-ity anomalies also indicates that NW faults,i.e.,the Puqian-Qinglan fault,may be shallower,while the E-W Wangwu-Wenjiao fault may be deeper,which perhaps extends down to Moho depth or deeper.
Using over 3 500 first P arrival times recorded by 9 digital seismic stations of the Hainan Digital Seismic Network during 1999-2005, a 3-D P-wave velocity model of the crust beneath Hainan Island and adjacent regions was determined. Our result shows that in shallow upper crust the spatial distribution of velocity anomalies is somewhat associated with surface geological structure in the region. A relatively low velocity anomaly appears north of Wangwu-Wenjiao fault, while a relatively high anomaly is found south of that fault. This spatial velocity variation is consistent with the following regional tectonic feature： northern Hainan Island is a depressional region with many active volcanoes and high geothermal activity, while central-southern Hainan is an uplifted and sta- ble region. In middle and lower crust the velocity is lower in eastern Hainan than that in western region, possibly suggesting the existence of hot materials upwelling from the mantle in eastern Hainan. The pattern of velocity anomaly also indicates that the NW-SE trending faults, e. g. , the Puqian-Qinglan fault, may be shallow, while the W-E trending Wangwu-Wenjiao fault may be deep, perhaps extending down to the Moho discontinuity.
出处
《地震学报》
CSCD
北大核心
2008年第5期441-448,共8页
Acta Seismologica Sinica
基金
The special project of Detection of Haikou City Earthquake Active Faults from the Tenth Five-year Plan of China Earthquake Administration (0106512)
Joint Seismological Science Foundation of China (105086)
CAS Key Laboratory of Marginal Sea Geology (MSGL0503).
关键词
三维速度
P波
地壳结构
海南岛
3-D velocity model
P-wave
crustal structure
Hainan Island
