Dynamic mechanism of volcanic belt and new understanding from earthquake evidence in Northern Hainan Island, China
琼北火山群形成的动力学机制及地震现象的新认识

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.