Dynamic mechanism of volcanic belt and new understanding from earthquake evidence in Northern Hainan Island, China
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摘要: 分析世界火山分布图发现琼北火山群分布在一南北向的火山带上，应用有限元方法模拟计算了双俯冲作用下海南岛所在雷琼\|越东火山带的形成机制，结合海南岛精确定位的地震数据和形变观测结果，认为琼北地区可能存在岩墙侵入或张性断裂膨胀，并根据地震数据模拟分析了岩墙侵入对区域应力场及形变的影响.琼北地区精确地震（2000~2006）定位结果表明地震主要集中在一个垂直面上，并且地震带两端有分叉现象.通过地震时空分布特征推测存在岩墙侵入，并通过数值模拟很好地解释了琼北地区地震的分布特征（狗骨头状）以及地表垂向形变东升西降的特征.Abstract: The world volcano map shows that on the Northern Hainan Island there is a NS-trending intraplate volcanic belt. In order to understand the mechanism of formation of the volcanic belt zone finite element method has been applied to simulate the double subduction (Indian plate subduction and Philippine plate subduction). The results show that double subduction induces double convection and between the two subduction zones forms an upwelling from the upper mantle to the surface, which is a possible reason of the NS-trending intraplate volcanic belt. Besides this result, the accurate location of earthquakes from 2000 to 2006 shows a vertical earthquake plane, we assume it is due to the magma intrusion in a vertical dyke considering the geological and geophysical information. We get the “dog-bone”-shaped distribution of earthquake and stress, also the “rising in east and falling in west” vertical deformation pattern by simulating the dyke intrusion, which are the same as the actual results.
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Key words:
- Double subduction /
- Dyke intrusion /
- Hainan Island /
- Finite element /
- Volcano
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