城市规划中抗震减灾的新构想——“强震发生断层”的发现和启示
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摘要
不是所有的活断层都会发生破坏性地震(5~6级以上),只有其中的极少数在未来数十年、数百年内有可能发生强震,特称之为强震发生断层。这种断层有一定宽度,一般为数米、数十米到数百米或更多。在断层范围内,地震波峰值加速度陡增,烈度可增加2°~3°或更多,抗震设计很困难。断层范围外,烈度随着离震中距离的增大而减弱,抗震按常规设计即可;台湾集集地震的观测数据却提示,0.15 g的抗震设计,竟能抵御0.5 g的破坏,抗震设计采用的地震动参数,蕴藏着巨大的抗震潜能,这使建筑物抗震达到人员零死亡的目标成为可能。强震发生断层的识别和圈定,从地震构造学的角度解决了地震预报的时、空、强三个要素。城市规划中在采用诸多有关抗震规范时,应考虑强震发生断层的有无及其增震作用,提请有关部门对规范作必要的修改和补充。
Though not all active faults will generate strong earthquake,people still turn pale at only mention of them.Strong earthquake will take place only on a fraction of the active faults in a time scale as long as tens or hundreds of years,so we call them the macroseism generating fault.The macroseism generating fault is not merely a line but has a certain width from several meters to tens or hundreds of meters or more.During a strong earthquake,the seismic intensity may increase abruptly by 2 to 3 or more degrees along the fault,so it brings forth much difficulty to anti-seismic design,or nearly makes the design impossible.Off the fault,the seismic peak ground acceleration decreases with distance.In anti-seismic design,the commonly-used seismic ground motion parameters(or the seismic intensity) often have a bigger anti-seismic potential,e.g.a building with a design acceleration of 0.15 g(intensity Ⅶ°)may actually resist a damage of 0.5 g(Ⅸ°).The discovery of macroseism generating fault enables us to deal with the three factors,i.e.the time,location and magnitude,of earthquake prediction from another aspect.When using the "ground motion parameter zoning map" in urban planning,correction and amendment are necessary as for whether or not the macroseism generating fault exists and its influences.
Though not all active faults will generate strong earthquake,people still turn pale at only mention of them.Strong earthquake will take place only on a fraction of the active faults in a time scale as long as tens or hundreds of years,so we call them the macroseism generating fault.The macroseism generating fault is not merely a line but has a certain width from several meters to tens or hundreds of meters or more.During a strong earthquake,the seismic intensity may increase abruptly by 2 to 3 or more degrees along the fault,so it brings forth much difficulty to anti-seismic design,or nearly makes the design impossible.Off the fault,the seismic peak ground acceleration decreases with distance.In anti-seismic design,the commonly-used seismic ground motion parameters(or the seismic intensity) often have a bigger anti-seismic potential,e.g.a building with a design acceleration of 0.15 g(intensity Ⅶ°)may actually resist a damage of 0.5 g(Ⅸ°).The discovery of macroseism generating fault enables us to deal with the three factors,i.e.the time,location and magnitude,of earthquake prediction from another aspect.When using the "ground motion parameter zoning map" in urban planning,correction and amendment are necessary as for whether or not the macroseism generating fault exists and its influences.
引文
[1]中国地震局编著.台湾集集地震照片[A].台湾9.21地震灾害图录[M]
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[4]程禹先生来信
[5]GB 18306-2001,中国地震动参数区划图国家质量技术监督局发布[S]
[6]徐锡伟,吴卫民,张先康,等.首都圈地区地表活动构造分布图[A].首都圈地区地壳最新构造变动与地震[M].北京:科学出版社,2002
[2]李,刘行松,杨美娥,等.昔格达层构造变形形成因素分析[J].中国地震,1995,1(3)
[3]李,黄广思,杨美娥.中国强震发生带地震构造的几点思考[J].高教地质学报,2001,7(3):245~255
[4]程禹先生来信
[5]GB 18306-2001,中国地震动参数区划图国家质量技术监督局发布[S]
[6]徐锡伟,吴卫民,张先康,等.首都圈地区地表活动构造分布图[A].首都圈地区地壳最新构造变动与地震[M].北京:科学出版社,2002
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