1982年卢龙地震前后的小震震源参数
SOURCE PARAMETERS OF SMALL EARTHQUAKES BEFORE AND AFTER THE 1982 LULONG EARTHQUAKE
-
摘要: 1982年10月19日,在唐山余震区的东北端卢龙,发生了一次ML=6.2(按北京电信传输台网的目录)的地震(3957'N,11904'E).为了监视卢龙地震前后小震震源参数的变化,本文考察了唐山-卢龙地区自1980年1月至1984年6月的情况.利用P波初动半周期,测定了160次ML=2.7——4.3的地震的震源参数.在所研究的震级范围内,初动半周期和震源半径不随ML而增大,应力降则随ML而增大.应力降的数值在0.1——50MPa的范围内变化,且主要集中在1MPa和5MPa之间.因此本文认为,对此地区,5MPa以上为高应力降,1MPa.以下为低应力降.该地区地震的空间分布表明,高应力降事件与随后发生的ML5的地震有明显的关系.在卢龙地震前一年多里,整个地区内的高应力降事件减少,低应力降事件增多;但在卢龙地震的震中附近发生了两次高应力降事件.Abstract: On 19 October 1982,an earthquake (3957'N,11904'E) with ML = 6.2 (according to Catalog of the Beijing Telemetered Seismic Network) occurred in Lulong on the northeastern edge of the aftershock zone of the Tangshan 7.8 earthquake of 1976. Earthquakes in the Tangshan-Lulong region from January 1980 to June 1984 have been examined for monitoring the variations in source parameters of small earthquakes before and after the Lulong earthquake. Source parameters of 160 earthquakes,2.7ML4.3,were determined using the P-wave first motions. In the magnitude range studied the P-wave first impulse width and the source radius do not increase with ML,and the stress drop increases with ML. The values of stress drop vary in the range from 0.1 MPa to 50 MPa,and are concentrated primarily between 1 MPa and 5 MPa; so in this paper stress drops of 5 MPa and more are taken as high stress drops and that of 1 MPa and less as low stress drops for this region. The spatial distribution of earthquakes in this region shows an apparent relation between high stress drop events and succedent ML5 earthquakes. Within one year and more before the Lulong earthquake,in the vicinity of its epicenter occurred two high-stress drop events,but in the whole reigon the number of high-stress-drop events decreased and that of low-stress-drop events increased.
-
-
[1] 陈运泰、林邦慧、李兴才等,1976.巧家、石棉的小震震源参数的测定及其地震危险性的估计.地球物理学报,19,206——233,
[2] 朱传镇、傅昌洪、罗胜利,1977,唐山7.8级地震前后微震震源参数.地球物理学报,20,264——269,
[3] Bakun, W. H., Bufr, C. G., and Stewart, R. M., 1981. P——wave spectra from d1a5 furcshocks and isolated earthquakes near Parkfield, California. Bull. Seism. Sov. Amer,71, 423——436.
[4] O'Neill, N. E., 1984. Source dimension and stress drop of small earthquakes near Parkfield, California.Bull. Seism. Soc, Amer., 74, 27——40.
[5] Frankel, A,and Knnamori, H., 1983. Determinatiion of rupture duration and stress drop for earthquakes in Southern California. Bull. Seism. Soc. Amen, 73, 1527——1551.
[6] Boatwright, J., 1980. A special theory for circular seismic sources, Simple estimates of source dimension,dynamic stress drop and radiated seismic energy, Bull. Seism. Sac, Ainer., 74, 1——28.
[7] 中国科学院地球物理研究所,1977.近震分析,256,地震出版社.
[8] 韦士忠、陈培善、辛书义,1986.由中小地震波谱研究华北北部地区的应力场和地震危险性,中国地震学会第三次全国地震科学学术讨论会论文摘要汇编,35——37,
[9] Brune, J. N., 1970. Tectonic stress and the spectra of seismic waves from earthquakes. J. Geophys Re.s.,75. 4997——5009.
[10] Schcrbaum, F., and Stoll, D., 1983. The 1978 Stwabian Jura aftershocks B+ll Scrsm. Sac. Amer.73,1321——1343.
[11] Archulata, R. J., Cranswick, E., Mueller, C., and Spudiclt. P., 1982. Source parameters of the 1980 Mammoth Lakes, California, earthquake sequence, J. Gcophyr. Res,87. 4595——4607.
[12] Aki,K 1967. Scaling law of seismic spectrum. .l. Geophys. Rer., 72. 1217——1230.
[13] Chouet, B., and Aki, K., 1978. Regional variation of the scaling law of eartliqnake source spectra. Bull.Seism.. Sor. Amcr.,68, 49——79.
[14] Zobin, V. M、1986. Variation in source parameters of small earthquakes before large earthquakes. Tectonaphysicr, 126, 229——243.[1] 陈运泰、林邦慧、李兴才等,1976.巧家、石棉的小震震源参数的测定及其地震危险性的估计.地球物理学报,19,206——233,
[2] 朱传镇、傅昌洪、罗胜利,1977,唐山7.8级地震前后微震震源参数.地球物理学报,20,264——269,
[3] Bakun, W. H., Bufr, C. G., and Stewart, R. M., 1981. P——wave spectra from d1a5 furcshocks and isolated earthquakes near Parkfield, California. Bull. Seism. Sov. Amer,71, 423——436.
[4] O'Neill, N. E., 1984. Source dimension and stress drop of small earthquakes near Parkfield, California.Bull. Seism. Soc, Amer., 74, 27——40.
[5] Frankel, A,and Knnamori, H., 1983. Determinatiion of rupture duration and stress drop for earthquakes in Southern California. Bull. Seism. Soc. Amen, 73, 1527——1551.
[6] Boatwright, J., 1980. A special theory for circular seismic sources, Simple estimates of source dimension,dynamic stress drop and radiated seismic energy, Bull. Seism. Sac, Ainer., 74, 1——28.
[7] 中国科学院地球物理研究所,1977.近震分析,256,地震出版社.
[8] 韦士忠、陈培善、辛书义,1986.由中小地震波谱研究华北北部地区的应力场和地震危险性,中国地震学会第三次全国地震科学学术讨论会论文摘要汇编,35——37,
[9] Brune, J. N., 1970. Tectonic stress and the spectra of seismic waves from earthquakes. J. Geophys Re.s.,75. 4997——5009.
[10] Schcrbaum, F., and Stoll, D., 1983. The 1978 Stwabian Jura aftershocks B+ll Scrsm. Sac. Amer.73,1321——1343.
[11] Archulata, R. J., Cranswick, E., Mueller, C., and Spudiclt. P., 1982. Source parameters of the 1980 Mammoth Lakes, California, earthquake sequence, J. Gcophyr. Res,87. 4595——4607.
[12] Aki,K 1967. Scaling law of seismic spectrum. .l. Geophys. Rer., 72. 1217——1230.
[13] Chouet, B., and Aki, K., 1978. Regional variation of the scaling law of eartliqnake source spectra. Bull.Seism.. Sor. Amcr.,68, 49——79.
[14] Zobin, V. M、1986. Variation in source parameters of small earthquakes before large earthquakes. Tectonaphysicr, 126, 229——243.
计量
- 文章访问数: 1574
- HTML全文浏览量: 14
- PDF下载量: 53
下载:
