The PLUM Method's Research In The Earthquake Early Warning System

China is an earthquake prone country,located between the circum-Pacific seismic belt and the Eurasian seismic belt.Throughout the history,earthquakes and natural disasters have caused huge economic losses and casualties in China.Wenchuan earthquake with magnitude 8.0 on May 12,2008,seriously damaged more than 100000 square kilometers,resulting in 69,227 deaths,374,643 injuries and 17,923 missing.It is the most serious earthquake after Tangshan earthquake.Earthquake Early Warning can effectively reduce the disaster caused by earthquake,and provide corresponding guidance for after earthquake rescue and emergency supplies distribution.The Propagation of Local Undamped Motion method(namely PLUM method),as a new method of earthquake early warning,can solve the problem of local intensity anomaly caused by multi-point simultaneous earthquake and fault expansion to one side.This paper mainly introduces the development of Earthquake Early Warning system,the method of instrument intensity in Japan,the method of instrument intensity in China and the principle and application of PLUM method.The main work of this paper is as follows:1.Summarize the development process of Earthquake Early Warning and intensity quick report at home and abroad,the installation of China's stations and the establishment of Earthquake Early Warning system.2.The development process of the instrument intensity of Japan Meteorological Agency: the method of instrument intensity of Meteorological Agency in 1996,the method of real-time instrument intensity in 2008 and the method of real-time instrument intensity in 2013.Through the calculation example,three methods of instrument intensity are compared and analyzed.3.The principle of the PLUM method,the regulations of Japan Meteorological Agency on the PLUM method,and the criteria for the division of early warning areas in Japan are described in detail.Taking the 7.3 magnitude earthquake in Japan on March 9,2011 as an example,this paper shows the early warning process of PLUM method and its advantages and disadvantages.4.Taking Jiuzhaigou earthquake in China as an example,the early warning process and accuracy of PLUM method are demonstrated by using Chinese instrument intensity method.The prediction formula of PLUM method is improved,and some suggestions for its implementation in China are put forward.