天祝-古浪5.4级地震震源机制和发震断层以及海原西断裂大震危险性讨论

研究了发生在海西断裂天祝拉分盆地1996年6月1日5.4级地震的震源机制，利用位于天祝－古浪地区的数字式微震监测台网纪录的余震的精确定位确定了本次地震的发震断层，研究表明这次地震是天祝拉分盆地中垂直于主断裂的近南北向断裂所形成，根据破裂模型和海原西断裂的应力积累状况，讨论了海原西断裂近期的大震危险性。     

1999年山西大同Ms 5.6地震的震源断层

大同震区先后在 1989、1991和 1999年发生MS >5地震 ,利用大同遥测地震台网的记录资料进行比较精确的地震序列震源定位 ,结合宏观烈度分布和震源机制解资料 ,详细地分析对比了 3次子序列的异同。结果显示 ,1999年MS5 .6地震的震源断层是走向NWW、长 16km、宽12km、埋深 5km以下、倾角近直立的左旋走滑断层。而前 2个子序列是NNE为主的右旋走滑断层活动所致 ,表明地震破裂方向发生了变化。这种 2个以上方向先后出现、并且强弱有别的地震破裂是普遍存在的 ,表明震源环境的复杂程度与地震序列的类型有关。虽然震区存在NE向的大王村断裂和NW向的团堡断裂 ,但目前没有证据说明震源断层和 2条构造断层连通。 3次子序列的震源断层都是走滑断层 ,也和 2条构造正断层有别。 1999年的子序列可能属于新破裂。     

2000年6月6日甘肃景泰5.9级地震震源机制解

20 0 0年 6月 6日 1 8时 59分 ,甘肃省景泰发生了ＭＳ5.9地震 .经甘肃省监测台网测定 ,该次地震震中位于 3 7. 0°Ｎ ,1 0 3 . 9°Ｅ ,震源深度 1 5ｋｍ .作者收集了甘肃及青海地区共 2 5个地震台站的Ｐ波初动符号 ,求出了该次地震的震源机制解 .见表 1和图 1 .矛盾比为 0 .2 8. 表 1　震源参数节面Ａ节面Ｂ节面应力轴Ｐ轴Ｂ轴Ｔ轴倾向 2 72° 1 88°方位角 2 3 5° 1 71° 1 3 4°倾角 82° 56°仰角 1 8° 54° 3 0°图 1　震源机制解Ｆｉｇ. 1　ＴｈｅｆｏｃａｌｍｅｃｈａｎｉｓｍｏｆＪｉｎｇｔａｉ 　　　 ＭＳ5. 9ｅａｒｔｈｑ…     

Mechanism of the June 4, 2000 Southern Sumatra, Indonesia, earthquake

Introduction The June 4, 2000 southern Sumatra, Indonesia, earthquake (16h28min26.2s UTC, 4.72, 102.09, 33 km, MS=8.0 [IRIS]) occurred under the Indian Ocean, near the Mentawai fault, along the well-known Sumatran subduction zone and the great Sumatran fault, all of which trend northwest-southeast. 1 800 houses were totally destroyed, 10 196 were heavily damaged, and 18 378 were slightly damaged by the earthquake. At least 97 people were killed, 1 900 were injured, and 122 000 were left…     

低电阻率油气层物理参数变化机理研究

研究了淡水环境下富含粘土矿物、细颗粒砂岩低电阻率油气层. 分析了粘土的附加导电性,认为粘土质量百分数高且富含伊利石和蒙脱石的地层中,若地层水质量浓度小于15g/L等效NaCl盐溶液时,粘土的附加导电性是造成油气层电阻率低的首要原因. 同时分析了细颗粒、粘土质量百分数不高的储层,高的毛细管压力使束缚水饱和度很高,同样能形成低电阻率油气层. 储层中粘土质量百分数的多少对储层岩石电性特征(I-Sw曲线形态)有重要影响,可用于指导测井资料解释模型的选择.     

新疆伽师强震群的震源破裂特征

利用国内外短周期P波初动符号及全球数字地震台网 (GDSN)的宽频带数字记录资料 ,研究了 1997年 1月 2 3日至 1997年 11月 4日伽师强震群的震源机制解和伽师强震群中的 5个强震、后续地震及其周边地震的震源破裂过程。从震源机制解来看 ,伽师强震群主要有走滑和正倾两种破裂类型 ,主压应力轴方向主要为NNE向和近垂直 ,而主张应力轴为NW向并近水平 ,与区域构造应力场方向存在差异 ,具有明显的局部特征。从破裂过程看 ,伽师强震群的破裂过程相对简单 ,破裂面积不大 ,上升时间较短 ,是由一点向四周快速扩散的脆性破裂 ,无明显的伸展方向 ,与阿图什地震完全不同。研究结果表明 ,伽师强震群与震源附近的地壳结构在垂向和横向上的非均匀变化有着密切关系 ,而阿图什地震与塔里木盆地的现今构造运动关系密切。伽师强震群是在震源区附近地壳上部垂向和水平向力共同作用下发生的多次沿NNE向的快速脆性破裂 ,从而形成了以张性破裂和左旋走滑为主的震源特征     

2001年11月14日新疆-青海交界8.1级地震

简要介绍了2001年11月14日新疆－青海交界8．1级地震的预测情况，给出了中、美、日等对此次地震的震源参数测定和震源机制，以及余震的分布和加卸载响应比随时间的变化。进而对震区近期地震趋势进行预测。     

Moment-tensor statistics of the 1997 Long Valley microearthquake swarm

Abstract. A simple, fast, moment-tensor inversion method using bandpass-filtered P-amplitudes was used to study the moment-tensor statistics of Long Valley caldera microearthquakes. The events were recorded in the summer of 1997, during a swarm in the caldera. The swarm was associated with geodetic extension, uplift, and subsequent moderate earthquake activity. The moment tensor solutions for 1,993 events were calculated using the new method. The majority of the resulting focal mechanisms appear to be explained in terms of double couple mechanisms. Since some events did exhibit considerable deviation from double-couples, the moment data were studied for their statistical significance. The moments of the actual data were compared to the moments of synthetic data with varying degrees of random noise in their spectra. The results of this study suggested that unless data from more than 20 stations are used and the earthquake epicenter is located inside or very close to the network area, moment-tensor inversion does not correctly resolve the non-double-couple components of microearthquakes. Analysis of the inversion residuals shows that the average noise in the P-wave spectra was close to 20%. The fluctuations of the volumetric components of the moment-tensor are in good agreement with those of the synthetic pure double-couples with 20% of added noise. Thus the moment-tensor statistics suggests that little if any volume change is required to explain the observed seismic energy release in the swarm. However, the statistics do show that a significant compensated-linear-vector-dipole component maybe present in the bulk of the seismicity. Given the network used in this study, such a component could not be precisely resolved for individual earthquakes. This possibility deserves further investigation because of its bearing on the nature of fluid-fault-earthquake processes in swarms.     

Focal Fault of the 1999 Datong Ms5.6 Earthquake in Shanxi Province

Several earthquakes with Ms≥5.0 occurred in the Datong seismic region in 1989,1991 and 1999,The precise focus location of the earthquake sequence was made by the records of the remote sensing seismic station network in Datong.Using that data together with macro-intensity distribution and focal mechanism solutions,we analyze the difference among three subsequences.The results show that the focal fault of the 1999 Ms 5.6 earthquake was a NWW-trending left-lateral strike-slip fault.It is 16km long and 12km wide.It developed at the depth of 5km and is nearly vertical in dip.The two previous earthquake subsequences,however,were generated by activity along NNE-trending right-lateral strike-slip fault.It can be found that the rupture directioin of the 1999 earthquake has changed.It is generally found that a rupture zone has more than two directions and has different strength along these two directions.The complicate degree of focal circumstance is related to the type of earthquake sequences.There is the NE-trending Dawangcun fault and the NW-trending Tuanbu fault in the seismic region,but no proof indicates a connection between focal faults and these two tectonic faults.The feature that focal faults of three subsequences are strike-slip is different from that of the two tectonic faults.It is suggested that the 1999 earthquake subsequence was possibly generated by a new rupture.     

中国市场群落发展机制

市场群落的崛起已成为21世纪初中国市场经济发展的新景观，在概述市场群落的基本特点后，揭示其形成和演化的动力机制；继而对单个市场与群落型市场上经营者的行为方式特征进行了比较分析，表明群落型市场具有多方面的竞争优势；指出市场群落的空间扩张还促进了经济国际化与本地化的有机融合发展，同时认为，市场群落持续发展的根本在于保证商人的可持续发展，并提出了相应的对策建议。