摘要
利用四川数字地震台网记录资料,计算2008年汶川地震后,川东南地区ML 3.0以上地震的震源动力学参数特征,分别得到视应力、应力降与震级之间、震级和地震矩之间,以及地震矩和视应力之间的定标关系。通过扣除震级影响,计算归准化视应力值的时空变化特征。得到结果如下:1从时间分布图来看,研究区4级以上地震频发时段刚好对应视应力涨落较明显时段,而该时段当地工业采矿注水活动强烈,故该区域视应力水平或许反映了工业活动对区域应力场的影响;2从空间分布图来看,自贡隆昌一带震级偏大,视应力反而偏小的现象可能与该区域应力释放不充分、构造应力水平偏低有关,未来要关注该区域发生中强地震的可能。
This paper obtains the following scaling relations after calculating the seismic source dynamically parametric features of earthquakes above ML3.0, which were observed in southeast Sichuan after Wenchuan earthquake by using the digital seismic data by Sichuan Seismic Network. Those scaling relations are: 1 Apparent stress &earthquake magnitude. 2 Stress dropping & earthquake magnitude,3 Earthquake magnitude & seismic moment. 4 Seismic moment & apparent stress. Based on the above relations, it further calculates features of spatio-temporal changes whose apparent stress is normalized, and thus reaches the following conclusions. 1 In the viewpoint of temporal distribution, earthequakeprone periods of researched zone of ML≥ 4.0 earthquakes happen to correspond to periods whose fluctuation of apparent stress is evident. Local intense mining water injection happened to be in the same time. Thus, the apparent stress level of researched zone might refl ect the industrial activity impact on the regional stress fi eld. 2 In the viewpoint of the spatial distribution, the reason why Zigong-Longchang area has larger magnitude whereas its apparent stress is relatively small might attribute to its insuffi cient release of apparent stress and low tectonic stress level. Special attention should be paid to the probable strong earthquake in this area.
引文
程万正,陈学忠,乔慧珍.四川地震辐射能量和视应力研究[J].地球物理学进展,2006,2(3):692-699.
陈学忠,李艳娥,郭祥云.2008年5月12日四川汶川8.0级地震前后震源区应力水平估计[J].国际地震动态,2008,6:1-3
陈学忠,王小平,王林瑛等.地震视应力用于震后趋势快速判定的可能性[J].国际地震动态,2003,7:1-4.
陈运泰.视应力//中国地震监测预报司.地震参数——数字地震学在地震预测中的应用[C].北京:地震出版社:2003:54.
华卫,陈章立,郑斯华等.三峡水库地区震源参数特征研究[J].地震地质,2010,32(4):533-541
华卫,陈章立,郑斯华等.水库诱发地震与构造地震震源参数特征差异性研究——以龙潭水库为例[J].地球物理学进展,2012,27(3):924-935.
龙锋,杜方,阮祥,等.用ETAS模型分析自贡矿井注水触发地震[J].中国地震,2010,26(2):164-171.
李航.川东南寒武系沉积相对储层的控制作用[J].内江科技,2013,6:175-188.
罗宇翔,曹哲,陈桂阳,等.川东南地区长兴组层序充填特征及沉积模式[J].天然气技术与经济,2012,6(6):11-14.
乔慧珍,程万正,陈学忠.安宁河-则木河断裂带地震视应力研究[J].地震研究,2006,29(2):125-130.
秦嘉政,钱晓东.云南地区地震视应力的时间和空间分布研究[J].地震学报,2006,28(3):221-229.
盛书中,万永革.地震视应力及其物理意义的探讨[J].地震地磁观测与研究,2008,29(1):36-43.
吴忠良,黄静,林碧苍.中国西部地震视应力的分布[J].地震学报,2002,24(3):293-301.
易桂喜,闻学泽,辛华,等.龙门山断裂带南段应力状态与强震危险性研究[J].地球物理学报,2013,4(56):1 112-1 120.
易志刚,宋茉,杨选辉,等.地震视应力在中国大陆西部强震趋势预测中的应用[J].地震,2007,27(4):110-120.
杨志高,张晓东.紫坪埔水库地区蓄水前后视应力标度率变化研究[J].地球物理学报,2010,53(12):2 861-2 868.
张致伟,程万正,梁明剑,等.四川自贡—隆昌地区注水诱发地震研究[J].地球物理学报,2012,55(5):1 635-1 645.
易桂喜,闻学泽,辛华,等,2008年汶川MS8.0地震前龙门山—岷山构造带的地震活动性参数与地震视应力分布[J].地球物理学报,2011,6(54):1490-1500.
阮祥,程万正,张永久,等.四川长宁盐矿井注水诱发地震研究[J].中国地震,2008,3(24):226-234.
Archuleta R,E Cranswick,C Mueller,et a1.Source parameters of the 1980 Mammoth Lakes,California,earthquakes sequence[J].J Geophys Res,1982,87:4 595-4 607.
Abercrombie R E and Leary P.Source parameters of small earthquakes recorded at 2.5 kin depth,Cajon Pass,southern California:Implications for earthquake scaling[J].Geophys Res Lett,1993,20(14):1 5l1-l 514.
Choy G L,Boatwright J L.Global patterns of radiated seismic energy and apparent stress[J].JGR,1995,100:18 205-18 228
Frank S.Carl K.Variations of apparent stresses and stress drops prior to the earthquake of 6 May 1984(mb=5.8)in the Adakseismic zone[J].Bull Seism Soc Am,1984,74(6):2 577-2 592.
Nuttli O W.Average seismic source—parameter relations for mid-plate earthquakes[J].Bull Seism Soc Amer,1983,73(2):519-535.
Kanamori H and Brodsky E E.The physics of earthquakes[J].Rep Prog Phys,2004,67(8):1 429-1 496.
Kanamori H and Rivera L.Static and Dynamic Scaling Relations for Earthquakes and Their Implications for Rupture Speed andStress Drop[J].Bull Seism Soc Amer,2004,94(1):314-319.
Wu Z L,Huang J,Lin B C.Distribution Of apparent stress in western China[J].Acta Seismologica Sinica(in Chinese),2(43):293-301.
Wyss M and Brune J N.Seismic moment,stress and source dimensions for earthquakes in the Galifornia-Nevada region[J].JGeophys Res,1968,73:4 681-4 694.