中国大陆中强地震序列类型的空间分布特征
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摘要
利用中国大陆1970年以来记录相对完备的294次5.0级以上的地震序列,研究地震序列类型的空间分布特征.结果表明:在西南地区,川滇菱形地块及其所控制的鲜水河—安宁河—小江地震带及金沙江—红河地震带以主余型序列活动为主,滇西和怒江—澜沧江断裂带以西腾冲—保山块体的龙陵、澜沧等地分布着较多的多震型地震,极少数孤立型地震主要分布于川西北地区,云南地区无孤立型地震.在西北地区,新疆南天山西段以主余型为主,其中柯坪块体与普昌断裂交汇区发生过多震型地震,天山中段则以孤立型地震居多;祁连山地震带以主余型序列活动为主;青海地区以主余型地震居多,但序列类型的区域特征不明显.在华北地区,阴山—燕山—渤海地震带、河北平原地震带及下扬子断块以主余型地震为主,山西地震带北段与NW向阴山—燕山地震带的交汇部位发生过5~6级多震型地震,华北地区南部北纬35°线附近以孤立型地震居多.序列类型空间分布与区域构造运动形式有关,断层内部闭锁单元或障碍体的破裂以及新生的、彼此分离的断裂段的破裂,大多产生主余型序列;多震型地震往往与共轭构造或多组构造交汇相联系;简单断层端部的进一步扩展一般产生孤立型地震.序列类型空间分布与区域深部介质环境也有一定关系,主余型地震大多发生在上地壳高速区或高、低速过渡带内,而多震型地震则较多地发生在上地壳低速区内.
Based on 294 earthquake sequences with magnitude greater than or equal to 5.0 occurred in Chinese mainland since 1970, the spatial distribution features of sequence types have been studied. In southwestern China, it takes mainshock-aftershock sequence type (MAT for short) as the major in Sichuan-Yunnan rhombic block and concerned Xianshuihe-Anninghe-Xiaojiang seismic belt, as well as in Jinshajiang-Honghe seismic belt. Multiple mainshock type (MMT for short) mainly distributes in western Yunnan, and Longling and Lancang areas in Tengchong-Baoshan block to the west of Nujiang-Lancangjiang fault zone. A few isolated earthquake type (IET for short) mainly occurred in northwestern Sichuan and there is no IET in Yunnan region. In northwestern China, it takes MAT as the major in west segment of south Tianshan in Xinjiang region, and some MMT also occurred in this area in intersection of Kalpin block with the Puchang fault zone. It takes IET as the major in middle Tianshan in Xinjiang. Along the Qilianshan seismic belt, most of sequences are MAT. In Qinghai region, it takes MAT as the major, but the regional feature of the spatial distribution of sequence types is not very clear. In North China, it takes MAT as the major in Yinshan-Yanshan-Bohai seismic belt, Hebei plain seismic belt and sub-plate of lower river area of Yangtze river. In intersection of north segment of Shanxi seismic belt and the NW-trending Yinshan-Yanshan-Bohai seismic belt, there were several moderate or strong MMTs with magnitude 5.0 to 6.0. In south of North China around the latitude line of 35°N, it takes IET as the major. The spatial distribution of sequence types is related to the modes of tectonic movements. MAT is mostly resulted from the ruptures of locked units or asperities or the neonatal separated segments inside the fault zones. MMT is generally related to the conjugate structures or intersection of more than two tectonic settings. Further extension of end of simple fault often produces IET. Spatial distribution of sequence types is also correlative to the regional deep environment of crustal medium to some extent. MAT mainly distributes in high velocity area in upper crust or in the transitional zone between high velocity area and low velocity area; MMT mostly occurred in the low velocity area in upper crust.
Based on 294 earthquake sequences with magnitude greater than or equal to 5.0 occurred in Chinese mainland since 1970, the spatial distribution features of sequence types have been studied. In southwestern China, it takes mainshock-aftershock sequence type (MAT for short) as the major in Sichuan-Yunnan rhombic block and concerned Xianshuihe-Anninghe-Xiaojiang seismic belt, as well as in Jinshajiang-Honghe seismic belt. Multiple mainshock type (MMT for short) mainly distributes in western Yunnan, and Longling and Lancang areas in Tengchong-Baoshan block to the west of Nujiang-Lancangjiang fault zone. A few isolated earthquake type (IET for short) mainly occurred in northwestern Sichuan and there is no IET in Yunnan region. In northwestern China, it takes MAT as the major in west segment of south Tianshan in Xinjiang region, and some MMT also occurred in this area in intersection of Kalpin block with the Puchang fault zone. It takes IET as the major in middle Tianshan in Xinjiang. Along the Qilianshan seismic belt, most of sequences are MAT. In Qinghai region, it takes MAT as the major, but the regional feature of the spatial distribution of sequence types is not very clear. In North China, it takes MAT as the major in Yinshan-Yanshan-Bohai seismic belt, Hebei plain seismic belt and sub-plate of lower river area of Yangtze river. In intersection of north segment of Shanxi seismic belt and the NW-trending Yinshan-Yanshan-Bohai seismic belt, there were several moderate or strong MMTs with magnitude 5.0 to 6.0. In south of North China around the latitude line of 35°N, it takes IET as the major. The spatial distribution of sequence types is related to the modes of tectonic movements. MAT is mostly resulted from the ruptures of locked units or asperities or the neonatal separated segments inside the fault zones. MMT is generally related to the conjugate structures or intersection of more than two tectonic settings. Further extension of end of simple fault often produces IET. Spatial distribution of sequence types is also correlative to the regional deep environment of crustal medium to some extent. MAT mainly distributes in high velocity area in upper crust or in the transitional zone between high velocity area and low velocity area; MMT mostly occurred in the low velocity area in upper crust.
引文
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陈培善,刘福田,李强,等.1990.云南地区速度结构横向不均匀性[J].中国科学,B辑,20(4):431~438
傅征祥.1982.强余震活动持续时间[J].地震学报,4(4):389~394
傅淑芳,刘宝诚.1991.地震学教程(第2版)[M].北京:地震出版社,1~578
郭大庆,刘蒲雄,袁一凡,等.1998.地震现场工作大纲和技术指南[M].北京:地震出版社,25
虢顺民,徐锡伟,向宏发,等.2002.龙陵—澜沧新生断裂带地震破裂分段与地震预测研究[J].地震地质,24(2):103~114
刘建华,刘福田,吴华,等.1989.中国南北带地壳和上地幔的三维速度图象[J].地球物理学报,32(2):143~151
刘蒲雄,陈修启,吕晓健,等.1996.地震序列的后续显著地震的预测研究[J].地震学报,18(1):27~33
苏有锦,秦嘉政.2001.川滇地区强地震活动与区域新构造运动的关系[J].中国地震,17(1):24~34
苏有锦,刘祖荫,蔡民军,等.1999.云南地区强震分布的深部地球介质背景[J].地震学报,21(3):313~332
吴开统,焦远碧,吕培苓,等.1990.地震序列概论[M].北京:北京大学出版社,97~114
许忠淮.2001.东亚地区现今构造应力图的编制[J].地震学报,23(5):492~501
周蕙兰,房桂荣,章爱娣,等.1980.地震震型判断方法探讨[J].西北地震学报,2(2):45~59
周蕙兰,房桂荣,章爱娣,等.1982.余震序列的持续时间[J].地震学报,4(1):45~54
KisslingerC.1996.Aftershockandfault-zoneproperties[J].AdvancesinGeophysics,38:1~36
MogiK.1963.Somediscussionsonaftershocks,foreshocksandearthquakeswarms—Thefractureofasemi-infinitebodycausedbyinnerstressoriginanditsrelationtotheearthquakephenomena(3)[J].BullEarthqResInstUnivTokyo,41:615~658
ReasenbergPA.1999.Foreshockoccurrencebeforelargeearthquakes[J].JGeophysRes,104(B3):4755~4768
RichterCF.1958.ElementarySeismology[M].SanFrancisco:Freeman,768
UtsuT.2002.StatisticalFeaturesofSeismicity[A].In:LeeWHK,KanamoriH,JenningsP,etaleds.InternationHandbookofEarthquakeandEngineeringSeismology,81A[M].Amsterdam:AcademicPress,719~731
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