Seismicity Of The Andaman Arc Area

In recent years, the world has entered a large earthquake active period.It has brought huge disasters to people.This paper main studies the Andaman arc area.Because it is at the junction of the India plate,the Australian plate and the Asian plate.So there were a lot of earthquakes happened here.It has happened many M>8.0earthquakes.The area happened M9.1earthquake in2004.After that,in2005,2007and2012happened MM≥8.0earthquakes again.This kind of phenomenon never be recorded in human history.This article will analyze M≥5.0earthquakes in Andaman arc by temporal distribution,frequency analysis and the focal mechanism solution.After I selective analyzed2004,2005,2007,2012M>8.0earthquakes,I got some conclusions.The Andaman arc area is located in the Pacific and the Mediterranean-Himalaya earthquake belt.So there are many huge earthquakes happened in it.Because of the extrusion from India-Australian plate.Most earthquakes are thrust fault type.Sumatra subduction zone is lateral subduction.Most of the focal mechanism solutions are thrust fault type.Java subduction zone is forward subduction.Most of the focal mechanism solutions are normal fault type.Because most of the focal mechanism solutions are thrust fault type.The P axis direction of M≥5.0earthquakes mainly NE trending.From the distribution of three kinds of focal mechanism in depth, shallow earthquake are mainly thrust fault type mechanism,the middle earthquakes are mainly normal fault type mechanism and deep earthquakes are strike fault type mechanism. From1900to2004,M≥7.0earthquakes showed a phenomenon which was active-calm-active.Since1994,M≥7.0earthquakes are mainly distributed in the Sumatra.They may have some trigger action to M≥8.0earthquakes.There are a lot of aftershocks filled the area.According to study some earthquake cases.I find if some places almost no earthquake took place.They are danger zone where may happen huge earthquakes.If some places had happened huge earthquakes,they are also dangerous.Because it may happen huge earthquake again.Pay attention to some places almost no deep earthquake.If there is deep huge earthquake happen,the area may be dangerous.These phenomenons may be helpful for earthquake prediction.We can study from the M8.6 earthquake in2012that the huge earthquake may develop in the interior of plate.