EARTHQUAKE FOCAL MECHANISM AND ITS TECTONIC SIGNIFICANCE ALONG THE TWO SIDES OF THE RED RIVER FAULT ZONE

作者：ZHU Junjiang ZHAN Wenhuan QIU Xuelin XU Huilong TANG Cheng

摘要：The Red River Fault Zone is a gigantic slide-slip fault zone extending up to 1000km from Tibet to SouthChina Sea. It has been divided into the north, central and south segments according to the difference of thegeometry, kinetics, and seismicity on the land, but according to the contacted relationship between the old pre-Cenozoic block in Indochina Peninsula and the South China block, the Red River Fault Zone was divided into two parts extending from land to ocean, the north and south segments. Since the Tertiary, the Red River Fault Zone suffered first the sinistral movement and then the dextral movement. The activities of the north and the south segments were different. Based on the analysis of earthquakes and focal mechanism solutions,earthquakes with the focus depths of 0-33km are distributed over the whole region and more deep earthquakes are distributed on the northeastern sides of the Red River fault. Types of faulting activities are the thrust in the northwest, the normal in the north and the strike-slip in the south, with the odd type, viz. the transition type, in the other region. These show the Red River Fault Zone and its adjacent region suffered the extruding force in NNW direction and the normal stress in NEE direction and it makes the fault in the region extrude-thrust,horizontal strike-slip and extensional normal movement.

发文机构：Key Laboratory of Marginal Sea Geology

关键词：TheRedRiverFAULTZone(RRFZ)FOCALmechanismsolutionsDextralMOVEMENTSeismicactivityThe Red River Fault Zone (RRFZ)Focal mechanism solutionsDextral movementSeismic activity

分类号： P315.2[天文地球—地震学][天文地球—固体地球物理学][天文地球—地球物理学]P315.3[天文地球—地震学][天文地球—固体地球物理学][天文地球—地球物理学]