地震重力异常形成机理及其在地震预报中的作用

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1、第36卷第1期地震工程学报Vo【．36No．12014年3月CHINAEARTHQUAKEENGINEERINGJOURNALMarch，2O14业业；短文l芥芥芥地震重力异常形成机理及其在地震预报中的作用①褚庆忠，武泽，邵先杰，李辉，陈禹(燕山大学，河北秦皇岛066004)摘要：分析了地震重力异常的形成机理，结合玉树、唐山和汶川三个地震实例阐述了重力异常现象与地震之间的对应关系。认为重力异常可以用来预报地震。流动重力观测和GRACE卫星观测是地震预报中常用的两种重力预测方法，前者可以进行较准确的中短期预报，后者可以进行长期预报。关键词：地震预报；重力异常；机理；

2、流动重力观测；GRACE卫星观测中图分类号：P315．726文献标志码：A文章编号：1000—0844(2014)01—0201—06D0I：10．3969／j．issn．1000—0844．2014．01．0201MechanismofGravityAnomalybeforeEarthquakeandItsRoleinEarthquakePredictionCHUQing—zhong。WUZe。SHA0Xian-jie，LIHui，CHENYu(YanshanUniversity，Qinhuangdao，Hebei066004，China)Abstract：Ea

3、rthquakesareamongthemajornaturaldisastersfacingtheworld．Earthquakescanthreatensafetyofpeopleandcauseseriousdamagetopropertyandtheeconomyofaregion．Ourcountryisonenationthathashadse—riousearthquakedisastersthroughouthistory，with4400largeearthquakesbeingrecorded．Seismicintensityis7de—gre

4、esorhigherfor60％ofthenation’sland，with50ofthecitiesand67ofthebigcitieslocatedinthesehigh(i．e．，≥7)intensityareas．Therefore，havingtheabilitytopredictearthquakeswouldhelptoreducetheriskposedtopeopleandhuman-madestructures．Thisarticleexaminesthegravityanomaly。oneoftheearthquakeforerunners

5、，andtherelationbetweengravityanomaliesandearthquakes．Thisstudyisbasedontheconceptthatwhentectonicmovementoccurs，theearth’scrustextrudesorextendsineverydirection．Asaresult，gravitywillbeinastateofimbalanceandundertheactionofanequilibriumforce．theearth’scrustwillrestoretoabalancedstablec

6、ondition．Duringthisadjustment，thegravityfieldwilladjustandchangeuntilbalanceisrestored．Aformulaisusedtobrieflydescribethethreeinfluencingfactorsthataffectedthegravityanomaly：thedensitychanges，movementoftheouterfluid，andchangesofmeasurementelevation．Inthesecondpartofthestudy，gravityvar

7、iationdiagramsaredrawnwithrespecttotimeandspacebeforetheearthquakeofYushu，TangshanandWenchuan．Itcanbeseenfromtheca—sesthatthegravityanomalybeforeearthquakesisobvious：gravitychangesconstantlyneartheepicenter。andthegravitygradientishigherthanusua1．Therearestrongtectonicactivitiesduringe

8、arthq