Research On Earthquake Location For Early Warning

Earthquake is a serious natural disaster to people’s life and propertysafety, which results in significant social impact. How to reduce the losscaused by the earthquake is of extraordinary significance. Earthquake earlywarning technique is the effective mean, which is an alternative to reduceearthquake damage and reduce casualties. In the earthquake early warning,reliable and rapid location information is one of key problems. Because ofthe requirement about time in the earthquake early warning, traditionallocation methods cannot meet the needs of earthquake early warning,reliable, rapid and real-time location method for earthquake early warning iscrucial. This paper puts forward a set of location method for earthquakeearly warning and this method uses three or four P wave information,calculating the earthquake epicenter. At the same time, this paper deriveslocation error formula theoretically and a location quality assessmentparameters using the assessment parameters to assess the quality of theresults.In this paper, the main results are as follows:1,The paper derivates location methods from real-time information ofthree and four P-wave seismic. It uses9artificial blasting data,29seismicdata within the network and68seismic data outside the net range100kmrecorded by the Fujian digital seismic network to validate the proposedmethod. Test results show that9man-blasting, three-station location deviate2.9±1.7km and four-station location deviate1.7±1.2km.29earthquakeswithin the network, epicenter deviation of three-station location method is9.6±6.4and epicenter deviation of four-station location methodis4.1±7.3km.68earthquake outside-net100km, epicenter deviation ofthree-station location method is19.1±24.0km and epicenter deviation offour-station location method is15.0±13.9km. The location accuracy of thismethod meets the need of the earthquake early warning. The average timeof three-station location method is7.6±1.9and the average time offour-station location method is9.6±1.6. The time meets the need ofearthquake early warning.2,The paper derives the location error formula about using three andfour P-wave to locate and the dimensionless parameter Dcto judge thelocation results. Test results show that artificial blasting all meet the errorformula.29earthquakes within the network,26earthquakes meet thethree-station location error formula,25earthquakes meet the four locationerror formula.68earthquakes outside the network,55earthquakes meet three location error formula,58earthquakes meet four location errorformula. Earthquakes within the network’s satisfaction rate is over85%earthquakes outside the network’s satisfaction rate is over80%.Dimensionless parameter Dccan be used to judge earthquake locationresults.3,The paper uses location error formula and gets the results of errordistribution map about using three and four P-wave to calculate locationinformation under the conditions of the Fujian Province of existing seismicobservation network (41stations) and new network (125stations).4,The paper analyzes the affecting factor of the quality of the location.We get that the accuracy P-wave’s picking up and density of observationstations will have a greater impact location results.