2012年河源M4.8级地震活动特征及预测研究
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摘要
对2012年2月16日河源MS4.8级地震序列进行研究,提出河源MS4.8级地震属于1962年河源MS6.1级主震后的晚期强余震,通过震源机制解结果分析,主压应力方向和华南地区主压应力方向基本一致,为走滑兼正断错动。水库西北角附近可能存在尚未明确的北西向小破裂带,b值计算表明河源库区1960年至今始终处于低应力状态,地震前40 d开始,河源微震频度(ML>0.1)和距震中30 km的深孔地电阻率同步发生明显高值异常。预测河源地区未来发生强破坏性地震的可能性比较低。
The research on M4.8 earthquake sequence of Feb.16,2012 shows that the earthquake was late strong aftershock of Heyuan MS6.1 principal earthquake in 1962.The focal mechanism solution identifies that the principal compressive stress of the earthquake has almost the same direction as that in South China,and is defined as strike-slip and fault rupture.The possible unconfirmed small broken belt in northwest of reservoir is also identified as the possible seismogenic structure for this earthquake.The b value calculation shows that Heyuan Reservoir areas were in the low stress state since 1960,so it is believed that strong destructive earthquake is unlikely to occur again in the future.It is noted that,40 days before this M4.8 earthquake hit Heyuan,the microseismic frequency of Heyuan(ML≥ 0.1) and deep borehole earth resistivity 30 km away from the epicenter simultaneously showed apparently abnormal high value.So far this is the only time that short-term information of seismometry and premonition with prediction significance was simultaneously acquired before happening of moderate strong earthquake in south China.
The research on M4.8 earthquake sequence of Feb.16,2012 shows that the earthquake was late strong aftershock of Heyuan MS6.1 principal earthquake in 1962.The focal mechanism solution identifies that the principal compressive stress of the earthquake has almost the same direction as that in South China,and is defined as strike-slip and fault rupture.The possible unconfirmed small broken belt in northwest of reservoir is also identified as the possible seismogenic structure for this earthquake.The b value calculation shows that Heyuan Reservoir areas were in the low stress state since 1960,so it is believed that strong destructive earthquake is unlikely to occur again in the future.It is noted that,40 days before this M4.8 earthquake hit Heyuan,the microseismic frequency of Heyuan(ML≥ 0.1) and deep borehole earth resistivity 30 km away from the epicenter simultaneously showed apparently abnormal high value.So far this is the only time that short-term information of seismometry and premonition with prediction significance was simultaneously acquired before happening of moderate strong earthquake in south China.
引文
①广东省地震局,2012年2月16日河源4.8级地震现场调查报告,2012.
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[1]丁原章,广东和香港地震风险概论[M].香港:商务印书馆,2004.
[2]王妙月,杨懋源,胡毓良.新丰江水库地震的震源机制及其成因的初步探讨[J].中国科学,1966,(1):85-97.
[3]魏柏林,冯绚敏,陈定国,等,东南沿海地震活动特征[M].北京:地震出版社,2001.
[4]沈崇刚,陈厚群,张楚汉,等,新丰江水库地震及其对大坝的影响[J].中国科学,1974,(2):1-32.
[5]易桂喜,闻学泽.多地震活动性参数在断裂带现今活动习性与地震危险性评价中的应用与问题[J].地震地质,2007,29(2):254-269.
[6]郭贵安,刘特培,秦乃刚,新丰江水库1961-1999年小震综合机制解结果分析[J].地震学报,2004,26(3):261-268.
[7]刘特培,秦乃岗,陈玉桃,阳江Ms4.9地震活动特征、影响场及应急对策[J].地震地磁观测与研究,2005,26(6):33-41.
[8]龚钢延,水渗透引起的应力场调整及岩石强度弱化的初步研究[J].西北地震学报,1990,12(4):56-59.
[9]龚钢延,谢原定.新丰江水库地震区内孔隙流体扩散与原地水力扩散率的研究[J].地震学报,1991,13(3):364-371.
[10]郑洪,王新蕾,王春媛,等,深井电极与地表电极的自然电场对比研究[J].地震,2000,20(1):85-89.
[11]陈运平,陈俊才,符干,1999年5月17日万宁近海M S 4.8地震地震[J].华南地震,20(1):37-42.
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