【摘要】 利用海南岛及邻区1999—2005年9个地震数字化台站记录到的3500余条区域初至波到时资料,确定了海南岛及邻区地壳三维P波速度结构.结果表明,该区域浅部上地壳的波速异常与地表地质构造有一定的相关性,即王五—文教断裂带以北地区波速较低,而以南地区为相对高的波速异常区.这与琼北地区为凹陷、并伴有多期火山活动和较高的地热背景,而琼中南地区为较稳定的隆起等构造特征相一致.在其中下地壳,琼东地区相对琼西地区波速较低,可能暗示了地幔热物质上涌等动力学过程.波速异常分布模式还暗示出北西向断裂带(如铺前—清澜断裂带)较浅,而近东西向的王五—文教断裂带较深,有可能延伸至莫霍面或更深.更多还原

【Abstract】 Using over 3500 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 stable 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.更多还原