We improved the traditional Cut and Paste (CAP) method in inverting point source parameters by combining local Pnl, surface waveforms and teleseismic P and SH waveforms, and then applied the method (CAPjoint) to study the source parameters of the 2010 Kaohsiung earthquake. The result shows that the best double-couple solution of the event is: 317 degrees, 36 degrees, 52 degrees for strike, dip and rake, respectively. The other nodal plane is 181 degrees, 62 degrees, 114 degrees with 21km focal depth. We tested the sensitivities of several parameters for data at different distances with typical mechanisms. Then we applied the bootstrap method to make statistics and verified that the joint inversion method is effective for constraining source parameters of moderate earthquakes, and the effect is especially good when the distribution of local seismic stations is sparse.

本文改进了传统基于近震波形数据的点源震源参数反演的Cut And Paste(CAP)方法,实现了近震Pnl波、面波和远震P波、SH波的联合反演的CAPjoint算法.对2010年3月高雄地震,分别进行单独反演以及联合反演,获得各自的震源机制解及深度,其中联合反演所得的最佳双力偶机制解参数为,节面1:走向317°,倾角36°,滑移角52°,节面2:走向181°,倾角62°,滑移角114°,深度为21 km.并对不同震中距波形对本次地震以及几种典型机制解断层几何参数的敏感性进行测试.为验证联合反演方法的可靠性,本文采用重抽样思想发展而来的Bootstrap方法,对近震数据的子集及其与远震数据的联合反演所得的参数进行统计,验证了在稀疏近台条件下联合反演中添加远震数据对地震震源参数约束的作用.

The North China area is divided into 11 sub-districts. Based on the recent 1 111 focal mechanism solutions of moderate and small earthquakes in North China，distribution features of the principal stress direction are analyzed employing grid test method. The result shows that the horizontal action plays a main role in the present tectonic stress filed in North China and the predominant directions of the maximam principlal compressive stress are NEE and EW. The directions of the maximam principlal compressive stress are EW in Tangshan sub-district and Southern Shanxi sub-district. The directions of the maximam principal compressive stress in other sub-districts of North China are NEE with values between 60° and 80°. The in-situ stress measurement by hydraulic fracturing in deep rock in Wanfu coal mine shows that the direction of the maximum horizontal compression stress is between 40° and 80°，which is well consistent with the analysis result of focal mechanism solutions of moderate and small earthquakes in the southwest of Shandong Province. Based on a tectonic comparison，the deep stress state in Wanfu coal mine is closely related to the tectonic stress filed in the southwest of Shandong Province.

将华北地区分成11个应力小区，依据华北地区近期1 111条中小地震震源机制解数据，利用格点尝试法分析华北地区主应力方向的分布特征，结果显示，华北地区现今构造应力场以水平作用为主，其中，唐山和晋南地区最大主应力方向为近EW向，其他地区最大主应力方向均为NEE向，方位为NE60°～80°。鲁西南万福煤矿深部水压致裂原地应力测试结果显示，水平最大主应力方向的为NE40°～80°，与鲁西南地区中小地震震源机制解的分析结果十分接近。通过构造类比，认为万福煤矿深部应力状态受控于鲁西南地区区域构造应力场。

Based on analysis of distribution of 2 660 earthquake focal mechanism solutions from “Database of Crustal Stress of China and Adjacent Area” (updated to December, 2003), the regional characteristics of focal mechanism solutions are studied. In the Northeast and North China stress regions, the orientations of maximum horizontal stress mostly are in the near EW direction and NEE-SWW direction. The strike-slip focal mechanism is predominant in Northeast and North China stress regions. In the South China stress region, the predominant orientation of maximum horizontal stress is in NE-SW direction. The focal mechanisms mainly include thrust faulting and strike-slip faulting. In the Xinjiang stress region, the predominant orientation of maximum horizontal stress is in near N-S direction. There is a significant number of thrust faulting events and strike-slip faulting events in Xinjiang stress region. In the south Tibetan stress region, the predominant orientation of maximum horizontal stress is in near N-S direction, and the focal mechanism solutions are of strike-slip and normal faulting. In the stress region of north Tibet plateau and in the northeastern edge, the predominant orientation of maximum horizontal stress is not concentrated, and the focal mechanisms mostly are of strike-slip faulting, with some normal faulting and thrust faulting.

利用《中国大陆地壳应力环境基础数据库》收录的中国及邻区2660个地震震源机制解资料(数据截止到2003年底),在分析中国及邻区震源机制解及其分布特征的基础上,重点分析探讨了中国境内6级以上地震的震源机制解的分区特征:东北-华北应力区震源机制解水平最大主应力的优势分布方位为近EW向和NEE向,震源机制解类型相对较为单一,以走滑型为主。华南应力区水平最大主应力的优势分布方位为NW-SE向,震源机制解类型主要是逆断型和走滑型。新疆应力区水平最大主应力的优势分布方位为近SN向,类型也主要是逆断型和走滑型。在青藏高原南部应力区,震源机制解水平最大主应力方位的分布相对比较集中,优势方位为近SN向,类型基本上只有走滑型和正断型2类。而在青藏高原北部及北东边缘应力区,水平最大主应力方位变化较大,震源机制解类型以走滑型为主,同时还有一定数量的正断型和逆断型震源机制解。

This paper discusses mainly the spatial distribution and change of stress orientation at focal depth around the Ordos fault block. The stress orientation are inverted by using the Grid Test Method from more than 3 000 earthquake focal mechanism solutions calculated from earthquakes with magnitude less than 5 recorded by local seismological stations around the Ordos during the years of 1980 to 1999. The region around the Ordos is divided into ten subregions based on neotectonic, geomorphologic and GPS data. The P and T axes being close to horizontal in all subregions implies that the Ordos and its vicinity are dominated by strike-slip motion. The spatial distribution pattern of the principal compressive stress axes around the Ordos Block appears as a fan convex toward the southwest of the Ordos Block. The mean orientation of the P axis is NE-directed in the west, ENE-directed in the north, and nearly E-W-directed in the south of the Ordos Block. In fact, the orientation of P axis in each subregion may vary with time. In 1992 and 1996, the direction of P axis in each subregions was gradually turned toward N75癊 direction. Based on the changes of P axis orientation with time in each subregion, three types of subregions are identified: the first type includes the areas where the orientation of P axis is relatively unchanged, such as the Weihe, Liupanshan and Yingchuan subregions; the second type includes the areas where the change of the orientation of P axis with time is complex, such as the Linfen and Tongxin subregions; the third type includes the areas where the orientation of P axis is sensitive to the earthquakes occurred nearby, such as the Datong and Baotou subregions. In Datong and Baotou subregions, the changes of P axis orientation doesn't simultaneously respond to the occurrence of an earthquake; when the direction of P axis in one subregion turns to NNE direction, then an earthquake will occur in this area. However, during the same period, the orientation of P axis in the other subregions doesn't turn to NNE direction. Another interesting thing is that the inconsistency ratio of the Grid Test Method for Datong subregion decreased before the Datong earthquake in 1989, while the ratio for Baotou subregion decreased before the Baotou earthquake in 1996.

利用格点尝试法首先分区对鄂尔多斯地块周边的3 000多个小震震源机制解进行了处理.结果显示,在震源机制解覆盖的时段内,地块周边地区的平均构造应力场有以下特征:地块周边主要以水平构造作用力为主,且其主压应力轴走向以地块西南侧为中心,从北至东呈扇形展布.在分区基础上,对各区的平均主应力轴分布进行了扫描,得到了其随时间的变化过程.其中渭河、六盘山和银川区的构造应力场相对稳定,临汾和同心区的构造应力场变化复杂,临河、包头、呼和、大同和太原区的构造应力场变化与该区的几次中强地震有密切关系.另外,地块周边除个别区外大多数区域在1992年和1996年前后,主压应力轴走向有趋近于N75°E的现象.

The Xingguo-Ningdu ore cluster in southern Jiangxi Province, located in the convergent zone of the eastern Nanling EW-trending metallogenic belt and the western Wuyishan NE-trending metallogenic belt, possess several different type of W-Sn polymetallic deposits. However, little research has been done for these deposits. Based on detailed field investigations, high-precision isotope dating on the Zhangjiadi Mo-W deposit, the time-space distribution of W-Sn ore deposits in Cathaysia Block and their geodynamic settings are studied in this paper. SHRIMP zircon U-Pb age for porphyritic fine to medium-grained biotite granite from the Zhangjiadi ore deposit is 154.1±1.8Ma. Molybdenites separated from the quartz vein type orebody in the Wangnipai ore block and the greisen orebody in the Liujiazhuang ore block yield Re-Os isochron ages of 158.4±3.1Ma (weighted mean age 157.7±1.4Ma) and 161.9±3.2Ma (weighted mean age 157.9±1.6Ma), respectively, which are corresponding to Late Jurassic period. The studied molybdenites show quite low Re contents (9.58×10 -6 ~22.65×10 -6 ), suggesting a continental crustal source of the ore metals. Integrated with the latest research results, it is concluded that the W-Sn deposits formed during 240~210Ma, 170~150Ma and 130~90Ma, and are centered by the largest scale in southern Jiangxi Province and southern Hunan Province, and become younger in the east, west, south and north directions. We suggest that the Yanshanian large-scale magmatic and ore-forming processes may have occurred in a Jurassic intraplate extensional geodynamic setting during the Mesozoic lithosphere extension in South China.

地处EW向南岭成矿带和NE向武夷山成矿带叠置部位的赣南兴国-宁都钨锡矿集区产有多处不同矿化类型的钨锡多金属矿床,但总体研究程度较低。本文基于详细野外地质调查,重点开展了张家地钼钨矿床的高精度成岩成矿年代学研究,并探讨了区域钨锡矿床成岩成矿时空分布及地球动力学背景。张家地钼钨矿化产于花岗岩与震旦纪浅变质细碎屑岩的内、外接触带,包括石英脉型(王泥排矿段)和云英岩型(刘家庄矿段)两种矿化类型。利用SHRIMP锆石U-Pb法,获得张家地钼钨矿区似斑状中细粒黑云母花岗岩的年龄为154.1±1.8Ma;利用辉钼矿Re-Os法,获得王泥排矿段石英脉型矿体的辉钼矿Re-Os等时线年龄为158.4±3.1Ma、加权平均年龄为157.7±1.4Ma,刘家庄矿段云英岩型矿体的辉钼矿Re-Os等时线年龄为161.9±3.2Ma、加权平均年龄为157.9±1.6Ma,厘定矿床成岩成矿时代为晚侏罗世,对应于华南中生代第二次大规模成矿作用。石英脉型和云英岩型矿体中辉钼矿的铼含量均较低(9.58×10 -6 ~22.65×10 -6 ),表明成矿物质以壳源为主;综合分析区域最新年代学数据资料,表明钨锡矿床成岩成矿具多期性,主要集中在240~210Ma、170~150Ma和130~90Ma,以赣南和湘南为中心,钨锡矿床向四周成矿年龄均呈变小趋势。燕山期钨锡大规模成岩成矿作用主要形成于华南中生代岩石圈伸展-减薄时期的侏罗纪板内拉张的地球动力学背景。

An earthquake of magnitude 5.5 had taken place in Xunwn, Jiangxi Province, on August 2, 1987. Its epicenter is located at 24? 58′N. 115?39′E and focal depth is 13km. The earthquake-generating structure and its rupture pattern by the shock are analyzed from the characteristics of earthquake hazards, data on activites of crustal structures, focal mechanism, preferred orientation of the damaged structures and the conditions of medium in this paper.

1987年8月2日,江西省寻乌发生 M S 5.5级地震,震中烈度Ⅷ度,震中位于24°58′N,115°39′E,震源深度13km。本文根据震害特征、地壳构造活动性、震源机制、建筑物破坏的优势方向和介质条件,对这次地震的发震构造及其破裂方式作了初步探讨。

Variation of Q value can provide the information of crustal stress, rock cracks, and fluid variation, and evidence to understand preparation and generation of earthquake. In this study, the amplitude data from the Annual Bulletin of Chinese Earthquake and the provincial earthquake bulletins of Sichuan and Yunnan were tentatively divided into 6 time segments. Tomographic M L amplitude method has been applied for each time segment to obtain temporal Q value variations. Firstly, a representative time segment with more than 14000 ray paths was selected to estimate the resolution and error of tomographic attenuation structure by adding random noise to original data and bootstrap method. Then, based on the detailed analysis of reliability, the same tomographic method with the same parameters was applied for all time segments. The research result shows that (1) the imaging error is small from the observation error of original data and ignoring radiation pattern of earthquake source. The error is less than 6% if 40% random noise is added to the original data. (2) The bootstrap method shows that the maximal error is less than 8% of average Q value, that means the tomographic results are stable and reliable because of huge data set in Sichuan and Yunnan region. (3) In checkerboard test, the resolution can reach 20' for the region with more than 50 ray paths in each cell. (4) The Q value variations were obtained after imaging for each time segment. A clear positive relation was found between the average Q value for each time segment and the number of middle and large earthquakes, in other words, the more earthquakes, the larger average Q , that may be resulted from the changes of regional stress. The relation between earthquake distribution and Q value variation was analyzed and we found that most of the large earthquakes did not occur in the maximal variation region of Q , but in the transition zone between maximal increase and drop of Q value. Maybe the differential stress has a maximal change in transition zone and the earthquake is easier to trigger.

Q 值的动态变化能够反映地壳应力、裂隙、地下流体等的变化趋势,为进一步理解地震的孕育发生提供证据.文中尝试将选自中国地震年报、四川省地震台网观测报告及云南省地震台网观测报告的数据分成6个时间段,分别对每个时间段的数据进行成像,来获得 Q 值的动态变化图像.首先选择一个具有超过14000条射线数据的时间段,通过原始数据加噪音的方法和Bootstrap方法对 M L 振幅成像的结果进行误差和可信度分析,然后在误差可接受的基础上,再对每个时间段的数据进行成像.研究结果发现:(1)原始数据的观测误差和忽略震源辐射花样对成像结果的影响比较小,40%的噪音所造成的结果误差最大不超过6%.(2)用Bootstrap方法获得的结果最大误差不超过平均 Q 值的8%,说明振幅层析成像方法在川滇地区的应用因采用大量数据所获得的结果是稳定可靠的,误差是比较小的.(3)分辨率测试发现,川滇地区在射线超过50条的区域,分辨率能够达到20'.(4)分别对每个时间段进行成像,从而获得 Q 值变化的动态图像.每个时段的区域平均 Q 值与中强地震的个数有明显的正相关关系,即地震个数越多,则区域平均 Q 值越大,这可能是区域整体应力变化的结果.通过分析地震的分布和 Q 值动态变化的关系还发现,大多数中强地震不是分布在 Q 值变化最大的区域,而是分布在 Q 增加和降低最大区域之间的过渡区域,这可能是由于差应力变化在过渡区最大,更容易触发地震造成的.

With more and more densely seismic stations deployed, a large number of P wave first motion data are observed, which provides us an opportunity to further study the tectonic stress field. In this paper, by using the 49844 P wave first motion polarity data from 8499 earthquakes, which occurred in and around the Ordos block from August 1, 2007 to July 21, 2013, we obtained the precise and detailed stress field in the study area. The composite focal mechanism method was used in this study. By fitting the focal mechanism radiation pattern with P wave polarity data from a large number of earthquakes, this method can obtain the composite focal mechanism in specific grid, and P, B, T axes can be regarded as the principal stress axes of the tectonic stress field. The grid search method is used to fit the focal mechanism radiation pattern, the focal mechanism which has the minimum contradictory ratio was regarded as the optimal solution. The inconsistent ratio is the ratio of the number of P wave first motion polarity which is inconsistent with the focal mechanism and the total number of P wave first motion polarity data, which is weighted by the distance of the earthquake epicenter to the grid point. The study results show that the stress field has the following characteristics: First, in the rift zone of the Yinchuan-Jilantai, Hetao, Daihai, Shanxi, and Weihe around the Ordos block, the main types of composite focal mechanism are normal types, and the strike of the nodal planes is consistent with the strike of the main fault which controls the boundary of the rift zone, that is, in accord with the extension regime in the rift zone around the Ordos block. Second, the main types of the composite focal mechanism are thrust, thrust-strike-slip and strike-slip types in the southwest boundary of the Ordos block, which reflects that the Ordos block is subjected to the northeastward squeezing of the Qinghai-Tibetan plateau. The principal compressive stress direction is eastward in the distance from the southwest boundary of Ordos block, that may derived from the northeastward squeezing of the Qinghai-Tibetan plateau, the principal compressive stress direction turns to NE-SW direction when near the Ordos block. Third, the P-axis azimuth shows generally regular changes except in some local areas. From south to north, the P -axis azimuth becomes more to the north direction in the west boundary of the Ordos block. From west to east, the P -axis turns more to the east direction in the north boundary of the Ordos block. In the south and east boundary of the Ordos block, the P -axis azimuth has small change and is parallel to the main fault's strike which controls the boundary of the rift zone. The dip angle of the P -axis is nearly horizontal in the southwest boundary of the Ordos block, and nearly vertical in the basins around the Ordos block. Fourth, the T -axis azimuth is NW-SE overall. The T -axis is generally perpendicular to the strike of the main fault which controls the boundary of the rift zone and the strike of the basin in the basins around the Ordos block. Fifth, under the NE pushing force from the Qinghai-Tibetan plateau and the NW-SE extension caused by the uplifting of the deep substance, the regions around the Ordos block are shear zones with extensional components, except for the compressional region in the southwest of Ordos-block; these results are consistent with the previous studies which suggest that the Circum-Ordos block is in extensional stress field, also better explain the fault basins surrounding the Ordos block, also accord with the formation of right-lateral shear zones with extension components in its western and eastern boundary and left-lateral shear zones with extensional components in its southern and northern boundary. Overall, we obtained the stress field around the Ordos block, and its general characteristics are consistent with the results of previous study, our results are more consistent with the basin structure around the Ordos block. In this study we focus on the general characteristics of our results. In the further study, we will pay more attention on the inconsistency of our study with the previous study, try to find out the reason and give a reasonable explanation; and pay more attention on the phenomenon of sudden changes in the direction of the stress axis, try to find whether it caused by the inhomogeneity of stress field, or the complex geological structure, or other reasons.

利用2007年8月1日至2013年7月21日发生在鄂尔多斯块体周缘的8499个地震的49844个P波初动符号资料,应用综合震源机制解法获得了鄂尔多斯块体周缘0.25°×0.25°的精细地壳应力场,所得应力场结果基本上覆盖了整个鄂尔多斯周缘地区.研究结果表明鄂尔多斯周缘地壳应力场具有以下特征: (1)在环绕鄂尔多斯周缘的银川—吉兰泰断陷带、河套断陷带、岱海断陷带、山西断陷带和渭河断陷带内,综合震源机制解结果以正断层型为主,且综合震源机制解节面走向大体与控制断陷带边界的主要断裂走向相一致,与鄂尔多斯周缘断陷带现今的拉张状态相一致.(2)在鄂尔多斯西南缘,综合震源机制解类型主要为逆冲、逆冲走滑和走滑型,反映了鄂尔多斯块体在西南缘受到青藏高原北东向挤压作用.鄂尔多斯西南缘的应力场的主压应力方向在远处为东向,源自于青藏高原向东北挤压作用,靠近鄂尔多斯块体表现为北东—南西向.(3) P 轴方位在局部地区变化较大,但总体呈现规律性变化. P 轴方位在鄂尔多斯块体西缘,从南向北,主压应力轴方位更加偏北;在其北缘,由西向东,主压应力轴方位更加偏东.在其南缘和东缘,主压应力轴方位变化不大,大体上平行于控制各断陷带主要断裂走向. P 轴倾角在西南缘为近水平,在其周缘各盆地内 P 轴倾角近直立.(4) T 轴方位总体表现为北西—南东向;在鄂尔多斯周缘各断陷带内, T 轴走向大体与控制断陷带主要断裂走向以及断陷盆地走向相垂直.(5)鄂尔多斯块体在其西南角受到来自青藏高原的北东向挤压和其东北角深部物质上涌形成的北西—南东向拉张力联合作用,上述作用使得鄂尔多斯块体周缘地区除西南区为挤压区外,其余区域均为剪切拉张区,与先前研究认为鄂尔多斯周缘地区处于引张应力场作用相符合,较好地解释了环鄂尔多斯周缘的断陷盆地构造,亦符合鄂尔多斯块体东西两侧的右旋剪切拉张带以及南北两侧的左旋剪切拉张带的认识.

The P-wave first motion polarity was picked up according to the seismic waveform data, which was recorded by the seismic station of Nantong city and its adjacent area in 2001-2011, the crustal stress direction of Nantong was calculated by using the composite focal mechanism method. 1391 P wave first motion data were used, we give each data a weight according to the distance between the earthquake and Nantong city, the total weight of the P wave first motion data is 289.39 after weighted, the P wave first motion contradictory ratio is 0.37 after weighted. The study results show that, the azimuth and dip angle of principal compressive stress axis are 97? and 53?, the azimuth and dip angle of middle principal stress axis are 196? and 7?, the azimuth and dip angle of principal extensional stress axis are 291? and 36?, respectively. Just one optimal solution was searched, shows that the resolution of research data is very high. The geographical location of Nantong city is between the tectonic stress region of north China and the tectonic stress region of south China, the azimuth of principal compressive stress axis we obtained is between the azimuth (NEE-EW) of principal compressive stress axis of north China stress region and the azimuth (NWW) of principal compressive stress axis of south China stress region, that reflects the continuity of the stress field. The dip angle of principal compressive stress axis is large, and the dip angle of the other two principal stress axes is relatively small, which is consistent with the normal fault of Nantong-Shanghai fault, the Nantong-Shanghai fault is through Nantong city, that reflect the reliability of our results.

根据南通市及周边地震台2001-2011年的波形资料,拾取P波初动,应用综合震源机制解法研究了该地区的地壳应力场方向,在本研究中使用了1391个P波初动.而在计算中,我们根据每个地震离南通市距离的不同赋予其P波初动符号不同的权重,加权后P波初动数据的总权重为289.39,加权后的初动符号矛盾比为0.37.研究结果表明:主压应力轴方位和倾角分别为97°和53°;中间应力轴方位和倾角分别为 196°和7°;主张应力轴方位和倾角分别为291°和36°.只搜索到一个最优解,说明研究数据的分辨率还是相当高的.南通市位于华北应力分区和华南应力分区之间,所得主压应力方位介于华北应力分区主压应力场方向NEE-EW和华南应力分区主压应力方向NWW之间,这体现了应力场的连续性.此外,主压应力轴倾角较大,其它两个应力轴倾角相对较小,和穿过南通市的NNW向正断性南通—上海断裂相吻合,反映了本研究结果的可靠性.

We apply the composite focal mechanism method and use more than half million P wave polarity data to invert for the 3-D stress field in Taiwan region. At a given location, composite focal mechanism is estimated using all the P wave polarity data originated from its neighborhood, and the data are weighted using a Gaussian distance weighting function. This method has the advantage of allowing maximum amount of data input in the solution, including polarity data from small earthquakes whose focal mechanisms are undeterminable with too few observation data available. Comparing to traditional focal mechanism estimation methods, this method produces focal mechanism estimates covering a broader area, and provides better averages of local focal mechanism solutions. We present: the focal mechanism result in a 0.25 degrees X 0.25 degrees X 2.5 km grid in Taiwan and its adjacent areas. The preliminary result shows that the P and T axis directions change markedly across the Moho discontinuity. The P and T axis directions in the 15 similar to 45 km depth range also correlate with P wave velocity perturbations and delineate the northwestward subduction of the Philippine Sea plate in northeast Taiwan. This 3-D stress field result may provide new constraints on geodynamics process in Taiwan region.

采用综合震源机制方法,利用503393个P波极性数据反演了台湾地区的三维应力结构.对于给定点,根据该点及邻近区域地震的所有P波极性数据采用地震综合震源机制进行估算,P波极性数据的权重由高斯距离函数给定.该方法可以采用大量P波极性数据,包括不能确定单个地震震源机制的P波极性数据.与传统的震源机制确定应力场的方法相比,该方法可以提供更好的震源机制的平均结果并覆盖更为广泛的地区.本文求得了台湾及邻区0.25°×0.25°×2.5 km的综合震源机制.初步结果表明, P 轴和 T 轴方向在Moho间断面附近变化明显. P 轴和 T 轴方向在15~45 km深度范围内与P波速度异常相关,描绘出菲律宾板块在台湾西北部的北西向俯冲消减.该三维应力场结果可为台湾地区的地球动力学过程提供新的约束.

On the basis of the “Basic database of crustal stress environment in China”, this paper summarizes the basic characteristics of recent tectonic stress field in China and adjacent areas, proposes the principle of dividing the tectonic stress districts. The recent tectonic stress field of China and adjacent areas is classified into four classes: The characteristic of the first order tectonic stress district shows uniformity and stability in large areas and long time. This stress field is mostly controlled by the geometry character of plate boundary and the force acting on plate boundary. The stress action of second order tectonic stress district shows coherence in a relatively large area. This stress field is controlled by regional block interaction. The stress regime of the third order tectonic stress district shows comparability in finite areas. This stress field is mostly influenced by interior block interaction inside the areas. The stress character (direction, intensity, structure, etc) of the forth order stress district shows better coherence. This stress field is mostly controlled by block and fault interaction. The paper preliminarily analyzes the dynamic environment which controlled the recent tectonic stress field in China and adjacent areas.

以“中国大陆地壳应力环境基础数据库”资料为基础，总结了中国大陆及邻区现代构造应力场的基本特征，提出了划分构造应力分区的原则，将中国大陆及邻区现代构造应力场划为四级应力区. 指出一级构造应力区主要受板块边界的几何特征和作用在边界上的力所控制，应力作用在大范围和长时间内保持均匀和稳定；二级构造应力区受控于区域块体间的相互作用，在较大区域范围内应力作用具有较强的相关性；三级构造应力区受控于区域内部块体间的相互作用，在一定区域范围内应力结构具有相似性；四级构造应力区受控于块体和断裂相互作用的影响，其应力性状(方向、强度、结构等)一致性较好. 论文还初步分析了控制中国大陆及邻区现代构造应力场分布的动力学环境.

The directions of mean principal stress axes in parts of Xinjiang and Xizang area are deduced from the polarity readings of P-wave first motion of a number of small earthquakes. Based on the results previously obtained for North China, the eastern and southeastern part of Chinese continent, after correcting the results for a few subrcgions in these areas with supplementary data, and adding the new results of this study for the Xinjiang and Xizang area, a map of the tectonic stress directions for Chinese continent is compiled.The uncertainties in deducing the mean P and T axes from P-wavc first motion polarity data of multiple earthquakes are estimated by applying the probability model proposed by Bril-linger et al. （1980）. The deviation of the P axes of individual focal mechanism solutions for large earthquakes from the mean P axes of the corresponding subregions is analysed, and thought to be possibly related to the frictional angles of the faults. Finally, this study sums up the main feartures of the tectonic stress field for the Chinese continent.

利用多个小地震的P波初动方向数据推断了新疆和西藏部分地区主应力轴的方向.根据以前华北、东部大陆和西南地区的工作结果,对个别地区补充新数据后重新作了分析;加上本文关于新疆和西藏地区的新结果,编制了我国大陆的地震构造应力场方向图.利用Brillinger等的概率模型,估计了用多个地震P波初动方向推断平均P、T轴的误差.讨论了单个大地震震源机制解的P轴与所在地区平均P轴方位角的差异.总结了我国大陆地震构造应力场的主要特征.

P-wave first motion, an unambiguous physical quantity, is a kind of steady seismic information. When enough data were available, it could be used to ideally determine focal mechanism solutions. The most popular method for employing P-wave first motion to determine focal mechanism solutions is the grid search method. However, when applied to earthquakes with few data points, grid search method still has great uncertainty, although it is believed to be better than the iterative method. By now, no satisfactory settlement has been found, which greatly restricts the application of this method. In this paper, we focus on the improvement of former grid search methods. Firstly, possible solutions are selected by weighted inconsistency ratio. Here, the weighting scheme retains the data-quality weighting factor so as to consider the influence of data quality, omits the weighting factor reflecting the distance between data points and nodal planes for avoiding over-reducing the weights of the observations near nodal planes, and adds another weighting factor which gives more power to sparse data points on the focal sphere for partly canceling out the influence of uneven distribution of the employed data points. Meanwhile, we divide the focal sphere into several roughly equal-square areas, which prevent deviation from real mean solution by artificial concentration of test solutions. We improve our inversion quality by employing jackknife technique, which enlarges the solution set by adding those possible solutions for one observation being ignored. This technique, along with clustering analysis, not only increases the possibility of finding out true solutions, but also makes us comprehend the quality of focal mechanism solutions unambiguously. Finally, we provide a new scheme for evaluating the quality of focal mechanism solutions based on the dispersion of selected solutions as well as the minimum weighted inconsistency ratio.

P波初动符号物理图像明确，是稳定的地震波信息.在资料充分时，可以较好地确定震源机制解.网格搜索法是目前流行的利用P波初动符号求解地震震源机制解的方法.不过，在实际观测资料不充分时，虽然较迭代算法优越，但网格搜索法依然有较大的不确定性.到目前为止，人们还没有找到合理的解决方案，极大地制约了这一类方法的应用.针对这一现状，本文在许忠淮提出的格点尝试法的基础上对网格搜索法进行了几个方面的改进.首先，采用新的加权方法计算加权矛盾比：权重因子包括反映初动符号质量的权重以体现资料质量的影响；不包括反映观测点与节面距离的权重以避免因节面附近资料权重的双重减小带来的系统偏差；通过减小震源球上密集资料点的权重以部分地抵消震源球上P波初动符号资料分布不均匀对可能解的影响.在通过加权矛盾比筛选可能的震源机制解时，把震源球分为面积相对均匀的网格进行解的搜索，避免了因网格划分不均匀所导致的平均解的计算偏差.针对资料不足情况下震源机制解会受控于个别观测点P波初动符号的情况，我们借鉴杰克刀（jackknife）技术，在可选解中增加了那些一个观测点被去除后的可选解，既对解的质量有了更好的把握，又增加了找到真解的可能性.进一步地，针对可选解存在多个解簇的情况，本文提出了通过聚类提供多组可选解的做法.最后，针对目前缺乏对解的合理评价体系的现状，提出了主要基于解的离散度并参考加权最小矛盾比对震源机制解质量进行评价的新方案.

The seismological observation system in China has experienced rapid development over the Tenth Five-year Plan period. The technical system construction of Data Backup Centre for China Seismograph Network is one of the most important parts of China Digital Seismological Observation Network program, which has been completed in Institute of Geophysics, China Earthquake Administration at the end of 2007. The data centre is capable of receiving near real-time continuous waveform data from more than 1000 permanent seismic stations, and also manipulating that data, including data quality control, data format converting, event data extraction by user order and data download service via internet. By now, we have supplied about 70 TB waveform data to over 70 researches of over 10 academic institutes and universities, especially the studies concerned with the Wenchuan great earthquake. The paper will give a brief introduction to the technical system construction, rapid response of data service to the Wenchuan earthquake studies, construction of automatic event-extracted system for rapid response of large earthquake in near real-time and data support to scientific researches.

“十五”期间中国地震观测系统得到了迅速的发展, 中国地震局地球物理研究所于2007年底完成“中国数字地震观测网络”项目“国家数字测震台网数据备份中心”技术系统的建设.该数据备份中心可以准实时地接收并存储全国1000多个固定地震台站的信号，具备海量数据校验、数据格式转换、以用户定制方式截取地震事件波形数据和数据网络下载的功能.到目前为止，已累计为国内10多个科研单位开展的70多项研究提供了近70TB海量波形数据的服务，特别在快速开展的汶川特大地震震后相关研究中提供了重要的数据支撑和保障作用.本文介绍了“国家数字测震台网数据备份中心”技术系统建设、汶川特大地震数据服务快速响应、大地震快速响应波形数据自动截取系统建设，以及对地震学及相关科学研究的数据支持情况.