The Anninghe-Zemuhe and Daliangshan fault zones are the western and eastern boundaries of the Daliangshan sub-block, respectively, both of which lie in a tectonic setting with potential major earthquakes. The purpose of this work is to estimate the seismogenic depths and seismic risks of these two fault zones relying on limited geodetic and seismic data. Firstly, we use a simple 2D elastic dislocation model to infer the slip rates and the locking depths along these fault zones. We calculate the 90%, 95% and 99% seismic cutoff depths and compare with those from GPS data. The results show that the locking depth of the north segment of the Anninghe fault is 6.2 km, less than half of 16 km for its 90% seismic cutoff depths. It implies that after the 1952 M(s)6(3/4)y, earthquake, this segment gradually tended to become locked. While within a depth range of 6-16 km, energy was released by seismic and aseismic slip, where exists deep creep. The north segment of the Daliangshan fault is completely locked within a depth range of 0 similar to 10 km, while the locking within 10 similar to 25 km is relatively weaker. The south segment of the Anninghe fault, the Zemuhe fault, middle and south of the Daliangshan fault are completely locked, of which the locking depths are close to the 90% cutoff depths of small events with a standard deviation of 0. 94 km. In addition, inversion of profiles A, B and C reveals that the movement of the Daliangshan sub-block from north to south exhibits clockwise rotation, consistent with the movement feature of the Sichuan-Yunnan block. The slip rates of the north, middle, and south segments of the Daliangshan sub-block are 9. 8 mm . a 1, 8. 9 mm . a 1 and 8. 4 mm . a 1, respectively, decreasing from north to south. The accumulated seismic moments of the Butuo fault and Jiaojihe fault, which lie in the south section of the Daliangshan fault, are capable to generate maximum magnitudes of M-W 7. 5 earthquakes, respectively. The elapsed times of the last events of these two faults are close to their earthquake recurrence intervals, and their earthquake occurrence probabilities are estimated to be 7. 1% and 5. 9%, respectively, which should receive much attention.

In this study, 1338 relocated earthquakes (M-s >= 1.6) from 1981 to 2018 and 53 GPS velocities from 2004 to 2017 were processed to obtain the geometry and kinematic characteristics of the Daofu-Kangding segment of the Xianshuihe fault system in southwestern China. By analyzing the seismicity depth distribution of the Selaha-Kangding fault, we inferred its three branches, the Yalahe fault, Selaha fault, and Zheduotang fault converged into one fault at a depth of approximately 15 km and that a flower-shaped structure was observed above this depth. Furthermore, based on a 2D elastic dislocation model, the creep rates, creep depths, slip rates, and locking depths of the Daofu-Kangding segment were analyzed. In case of the Daofu-Qianning fault, the obtained left-lateral slip rate was 4.5 +/- 1.1 mm/a and the locking depth was 5.3 +/- 1.9 km. Because the fault creep rate from a depth of 2.6 km to the surface was 1.3 +/- 1.0 mm/a, the Daofu-Qianning fault cannot generate earthquakes having magnitudes of greater than 7 in the near future. However, the slip rates were 7.5 +/- 1.6, 2.3 +/- 1.5, and 1.9 +/- 1.5 mm/a by assuming a locking depth of 15 km for the Selaha fault, Yalahe fault, and Zheduotang fault, respectively. Furthermore, because the creep depth of the Selaha fault was 3.4 +/- 1.6 km and the creep rate was 7.5 +/- 2.8 mm/a, the accumulated seismic moment since 1725 corresponded to a M(w)7.1 earthquake.

The Xianshuihe fault zone is divided into five segments along its strike. Fault activity parameters are estimated by using crossing fault measuring data of short baselines and short leveling at sites along the fault zone. Regional dynamic gravity and GPS velocity fields are calculated by using gravity and GPS observational data of a large area covering the whole fault zone. We use the ant colony algorithm and particle swarm optimization (PSO) based on resulting data above to invert the fault activity parameters of the five fault segments, and the strike-slip component of each segment is taken as the current fault slip rate. Then we analyze the differences between the three types of the current slip rate as well as geological average slip rates of the five segments, taking the strike slip rate inverted from gravity data as the slip rate of the whole fault zone. Comparing the whole near-field fault rate with the result of short baselines and short leveling, we determine the features of fault segments measured by short baselines and short leveling, and provide the current overall strike-slip rate of the five segments and several branch faults. The resulting slip rates are as follows: (1) 9. 13 mm . a(1) on the Luhuo segment; 2. 46 mm . a (1) on the west branch fault and 5. 84 mm . a (1) on the east branch fault in the Xialatuo area. (1) 8. 57 mm . a (1) on the Daofu segment; on its southeast section, the west branch in the Goupu is 1. 78 mm . a,and the east branch is 6. 79 mm . a (3) 7. 67 mm . a (1) on the Qianning segment. (4) 6. 14 mm . a (1) on the Kangding segment. And (5) 4. 41 mm . a (1) on the Moxi segment. Moreover, we also discuss qualitatively the 3D elastic-plastic deformation model of active blocks on both sides of the fault zone covered by gravity and GPS data and permanent displacements caused by paleoand historical earthquakes.

文中系统整理并计算了1988年以来鲜水河断裂带地区流动重力复测资料,参照以往震例研究总结提出的重力场变化异常指标,分析了区域重力场时-空动态变化及其与测区内发生5级以上地震的关系,进一步研究了区域重力场变化的时-空分布特征及其机理,讨论了近期区域重力场动态变化的强震危险含义.结果表明:1)流动重力测量具备了检测地壳运动与5级以上地震事件的能力;2)1988年以来测区发生的13次5级以上地震中的8个地震与年际重力场变化有较为确定的对应关系,可依据年际重力场变化确定前兆异常,其中3个6级以上地震在异常图像发展3～4a后发生,4个发生在无资料区的地震事件不能确定前兆异常;3)测区重力场的1个明显特征是2004年以前区域重力场时空动态变化图像呈整体的南北贯通,且年度间为正、负值交替变化,其间所发生的5级以上地震不沿鲜水河断裂带分布.重力场变化值反映2004年以前存在2个相似的地壳物质移动波,对应了研究区地震时空分布由强到弱的过程.2010年以后的图像变化为年度内的局部正、负值区域同时存在,无年度间的正负交替变化现象,其间5级以上地震基本发生在断裂带上.1988年以来测区重力场动态变化与地震分布符合印度板块NE向运动强、弱分期的动力学模式,可据此优化重力异常指标.根据文中的分析总结和近期重力场变化趋势,提出磨西断裂北段区域具有中-长期强震危险性的初步结论.

There is the special structure combination and the concentration of strong earthquake in the Pu'er block.The geology phenomena of motion and deformation caused by motion of the active fault and the sub-block which brings the extensive attention and further research to the scholar of geological society.Basing on the past research achievements,we will construct the 2 dimensional shell finite element model of Pu'er region containing the active fault.Applying the velocity of block per year measured by GPS data and the researches on the geology and geomorphology as the boundary conditions of finite element model,we then compute the spatial distribution of deformation in the Pu'er region and simulate the deformation displacement along the NEE and NNW direction.Lastly,we analyze the characteristics of horizontal and vertical displacement field in the Pu'er region.The numerical result shows that extension motion of the southeastern margin of the Qinghai-Tibetan Plateau makes the movement of slump due to the gravity.In the research area,the motion of fault with NEE strike draws the fault with the NNW strike to move in conjugation direction.The vertical deformation caused by the uplift movement is agreed with the result of 60 years of larger regional leveling and the deformation along the NNW direction is distributed irregularly which is made possible by the regional stress accumulation and adjustment after the earthquake.The deformation field along the NEE direction is larger in western part of Pu'er region than that in eastern part,especially the northwest part of region which is corresponding to the recent Jinggu Ms6.6 earthquake.Lastly,we analysis preliminarily the dynamic problems in research area.

Using the permittivity and resistivity data of 239 measuring points which were collected from seven typical loess profiles in Yanchang,Luochuan and Baoji area of northern Shaanxi,the authors summarized the dielectric and resistivity characteristics of loess,and found that the loess layer and the red soil layer could be significantly distinguished according to their electrical properties.Then the relationship and influence factors of electrical parameters of loess in northern Shaanxi were discussed.With the most detailed Chang-10-well loess section in Yanchang area as an example,the electrical characterization and description of the Chang-10-well loess section were described in detail.In addition,the following three problems were preliminarily explored:the theoretical feasibility for electromagnetic method such as GPR(ground penetrating radar) to distinguish clay layer in the Loess Tableland;whether it's necessary to eliminate the influence of moisture content on electrical parameters;the establishment of a scientific earth-electricity model.The results obtained by the authors provide the theoretical foundation of loess electrical characteristics and the basis of interpretation for electromagnetic profiles and earth-electricity model of loess so as to probe into electromagnetic methods such as GPR (ground penetrating radar) for distinguishing clay layer in the Loess Tableland.

为研究普洱—宁洱地区强震频发与构造应力场和变形场的相关性,以1997-2007年GPS数据计算得到的云南普洱—宁洱块体年运动量为边界约束,建立云南普洱—宁洱地区包含红河断层及澜沧江断层等10个断层的三维摩擦接触有限元模型,计算在GPS年运动速率约束下棋盘式构造格局的变形位移场、应变场及应力场分布,并将计算结果与GPS计算结果进行比较.通过计算发现:普洱—宁洱断层群会使澜沧江及红河断层包围区域变形及应力场更复杂,普洱—宁洱地区复杂变形及应力场可能是该地区中强地震频发的主要原因;镇远—普洱断层可能是影响普洱—宁洱地区变形及应力场的主要断层;普洱—宁洱地区走向共轭断层交汇处,存在较大变形及应力值;变形场与应力场会随断层走向变化而发生变化,在断层走向变化剧烈部位有较大值.

This work is based on 60 strong earthquake records from 20 stations within a distance of 100 km of the epicenter of the Lushan earthquake provided by the China Strong Motion Net-work Center (CSMNC).In this study,we applied zero-crossing and linear acceleration methods to calculate the predominant period and response spectra in three directions from the 20 stations with a damping ratio of 0.05.We then computed the distributions of the peak and predominant periods of the response spectra,the amplification coefficient in the computational region,and their mean values in the hanging wall and foot wall of the fault.Results showed that the peak and pre-dominant periods of the response spectra and the amplification coefficients were different at all 20 stations.The response spectra showed the hanging wall effect and the characteristics of rapid ground motion decay in the hanging wall.Within 100 km of the epicenter,the predominant period was almost equal at both the hanging wall and foot wall.In fact,the mean value of the predomi-nant period in the EW and UD directions in the hanging wall was slightly less than in the foot wall,and the mean value of the predominant period in the NS direction in the hanging wall was slightly larger than in the foot wall.In general,the predominant period in the UD direction was less than in the horizontal direction,and the range of the predominant period in all directions on both sides of the fault was 0.013~0.275 s.The amplification coefficient in the NS direction at 80 percent of the stations was larger than that in the EW direction;therefore,the larger amplification coefficient in the NS direction is possibly the main reason for the landslide during the Lushan earthquake.

Using mobile gravity measurements from 2011. to 2015 in northeastern margin of Tibetan plateau, we have systematically analyzed the regional gravity field changes and their relation to the M(S)6.4 Menyuan earthquake on January 21, 2016. Combined with GNSS, leveling observations and regional geology, the time-space distribution of the gravity field and its mechanism were further studied.The results show that in the space domain, the gravity field variation is closely linked with the Qilianshan fault. The relation shows that tectonic activity or deformation caused surface gravity changes along the Qilianshan fault during 2011 and 2015. During the early period before M(S)6.4 Menyuan earthquake, regional gravity anomalies in a large area appeared in the measurement region. Gravity changes showed relative locking before the impending earthquake, and gravity field variation distributed in a four-quadrant form. The earthquake happened in the process of gravity reverse changes and the anomaly variations near Menyuan and Tianzhu were over 100 X 10(-8) m . s(-2). Dynamic evolution characteristics of the gravity field generally reflect the dynamic effects of the moving material of the northeastern margin of Tibetan plateau which spread toward east, and the Menyuan epicenter zone by the earth's compression deformation, where compression ratio and gravity change are most significant. The spatial distribution of the gravity field and its changes over time and vertical and horizontal crustal movement and tectonic activity observations have certain corresponding relationships.To study the relation between regional gravity changes and seismic activity is a meaningful method that is developed in recent years. Gravity dynamic variation has important implications for location prediction, which can provide experience and reference for medium-term forecast. Great earthquakes tend to occur at the center of four quadrant distribution of gravity changes or the gradient/transit belts from positive to negative anomalies. The M(S)6.4 Menyuan earthquake occurred nearby the zero contour close to the center of four quadrant distribution of gravity changes.

Using the gravity remeasurement data from 2011 to 2014 in the Sichuan-Yunnan region, We have systematically analyzed the spatial-temporal variations of the regional gravity field and their relation to the occurrence of the Yiliang M(S)5. 7 earthquake in 2012, Lushan M(S)7.0 earthquake in 2013, Ludian M(S)6. 5 earthquake and Kangding M(S)6. 3 earthquake in 2014. Combined with GPS data and leveling observations and regional geologic structure, the time-space distribution of the gravity field and its mechanism were further studied, and its implication for seismic risk is discussed. The interannual variation of gravity dynamic change in the Sichuan-Yunnan region during 2011 to 2012, 2012 to 2013, 2013 to 2014 and the accumulation change during 2011 to 2014 are analyzed. And we have discussed the evolution characters of the gravity field. Combined with regional gravity field variation and seismic activity, and with GPS data during 2011 to 2014, and leveling data during 1971 to 2011, we have found the relationship between strong earthquake and gravity variation in recent years. And on this basis, combined with regional geology structure, we further assess the seismic risk in the Sichuan-Yunnan region in the future. The results show that gravity variation is closely linked with the fault activity in the Sichuan-Yunnan region. It is caused by material migration accompanying active faulting and crustal tectonic motion. The gravity data from the survey area since 2012 have obvious response to four major earthquakes (M-S>5. 7). Regional gravity anomalies and a gravity gradient change may be a seismic precursor. Dynamic evolution characteristics of the gravitational field roughly reflects the dynamic effects of the moving material of the Tibetan plateau which spread toward east and the Longmenshan fault zone by the crust uplift, where compression rates and gravity change are most significant. The spatial distribution of the gravity field and its changes over time and vertical and horizontal crustal movement and tectonic activity observations have certain corresponding relationships. To utilize the remeasurement data to regional gravity change, we have researched its relationship with seismic activity. Gravity dynamic variation has important implications for location prediction of earthquakes, providing experience and reference for medium-term forecast. Earthquakes are easy to occur in four quadrant distribution centers of gravity change or high gradient belts of positive and negative anomalies. Some areas of gravity anomalies have medium-long term seismic risk.

Using the observation data of relative gravity measurements from the northeastern edge of the Tibetan plateau,we have systematically analyzed the spatial-temporal variation of the regional gravity field and their relation to the occurrence of the MS6. 6 Minxian-Zhangxian earthquake on July 22,2013. Our research mainly shows that: 1) Spatially the anomaly change of the regional gravity field is closely related to the major fault zones in the region,suggesting that the tectonic activities or deformation which happened along the fault zones( or segments) during 2011 to 2013 would have resulted in the variation in the ground gravity observations. 2) Before the MS6. 6 Minxian-Zhangxiang earthquake,regional gravity anomaly firstly appeared in the whole study region,and then local gravity anomalies and high gradient zone of gravity change appeared at and near the potential source area.Among the areas of gravity anomalies,the anomaly variations near Linxia and Minxian were up to and over 150×10-8ms-2,indicating possibly the tectonic movement or stress enhancement in the study region and around the potential source area,which could be related to the preparation and occurrence of the earthquake. 3) The dynamic change patterns and the differential evolution patterns of gravity variation of one year scale suggest that significant anomalies of gravity variations in the mobile gravity measurements appeared indeed in the last two years of the preparation process of the MS6. 6 MinxianZhangxian earthquake. The earthquake occurred on the NE-trending high gradient zone near the zero curve and the turning part of contours of gravity change. 4) To a certain degree,we made a mediumterm forecast before the Minxian-Zhangxian MS6. 6 earthquake,especially a forecast for the locality of the earthquake based on the anomalous gravity variations.

The observed results of repeated absolute and relative gravity measurements in Chengdu arear during 1996 similar to 2008 are systemically analyzed, and then discuss the relationship between gravity variation of Longmenshan fault zone and Wenchuan M(s)8. 0 earthquake. The results show as follows. (1)The change of gravity field is closely relative to tectonic movement of Longmenshan fault zone. The change of surface gravity field caused by the active faults associated with the mass transfer and structural deformation can be effectively reflect by gravity measurements. (2)The dynamic images of gravity field in Chengdu arear base on absolute gravity measurements can express the precursory gravity information during the selsmogenic process of the Wenchuan M-s 8. 0 earthquake. (3) The temporal changes' value of gravity point (Yingxiu, Beichuan) cumulate to 120 X 10(-8)m.s(-2) shows that gravity field near meizoseismal region have fast increased after the Wenchuan M(s)8. 0 earthquake. (4)Before Wenchuan earthquake, the gravity anomaly in the Sichuan Basin on the east side of Longmenshan fault zone is relative stability, and the gravity anomaly in the West Sichuan Plateau on the west side of Longmenshan fault zone is significant changes.

利用跨鲜水河断裂的二对GPS连续观测点资料,获得了跨鲜水河断裂高精度形变场(误差约1 mm)的动态演化轨迹.该轨迹清晰地反映了鲜水河断裂乾宁段和道孚段形变场的明显不同,前者为稳态、后者为非稳态.道孚段的非稳态形变可能与鲜水河断裂在此分段并呈现东、西二支有关.采用一多段脆韧转换带模型对形变场动态演化给出初步的模拟与解释:鲜水河断裂南段转换带内蠕滑稳定,而北段和道孚段呈现间歇状态且平均滑移率高于南段.这可能与断层面介质的物理性质有关,揭示当前断裂南段转换层强度可能高于北段,对应于更长的发震周期.

Highly precise (σ ∼1 mm) temporal deformation measurements are taken across the Xianshuihe fault from two pairs of continuous GPS stations straddling the fault. Baseline vector changes of the two pairs of stations show clearly the difference in deformation behavior between the Qianning and Daofu segments of the fault: the former deforms steadily, and the latter deforms with a strong transient component. The transient deformation across the Daofu segment is possibly related to its irregular geometry, where the fault splits into two branches, that is, the east and west branches. An attempt is made to interpret the baseline vector changes using a kinematic fault model composed of a brittle layer in the upper crust, a ductile layer in the lower crust, and a transition zone in between. The slip in the transition zone of the south segment of the Xianshuihe fault is steady. The slips in the transition zones of the north and Daofu segments of the Xianshuihe fault, however, are not steady, and the average slip rates there are higher than that of the south segment. The difference in deformation behavior is probably associated with the rheological properties of the fault interface, suggesting that the overall fault strength of the south segment is greater than those of the north and Daofu segments, corresponding to longer earthquake recurrence time.

以GPS数据给出的川滇地区(96°~108°E,21°~35°N)速度场为约束,依据研究区已知断裂分布情况建立连接断层元模型,用最小二乘方法反演了该地区主要活动断层的现今错动速率.结果显示,印藏碰撞引起的北北东向推挤和高原隆升引起的重力势能作用造成青藏高原物质东向挤出.遇到来自稳定华南块体的阻挡后,高原东南部物质相对稳定欧亚板块转向南东方向继而向南运动,使得川滇地区围绕喜马拉雅东构造结作顺时针转动,造成川滇地块东侧断裂作左旋走滑活动,而其西侧断裂以右旋走滑活动为主.其中甘孜-玉树、鲜水河、安宁河、则木河、大凉山、小江断裂及其向南西方向延伸的部分和打洛-景洪、湄沾断裂构成青藏高原东南部东向挤出的东北边界和东边界,左旋速率分别为0.3~14.7,8.9~17.1,(5.1±2.5),(2.8±2.3),(7.1±2.1),(9.4±1.2),(10.1±2.0),(7.3±2.6)和(4.9±3.0)mm/a.青藏高原东南部东向挤出的西南边界似乎不是由单一断裂带构成,而是在较宽范围内形成的一条右旋剪切带.位于红河断裂北东侧的南华-楚雄-建水断裂和西南侧的无量山断裂带、龙陵-澜沧断裂活动性较强,分别具有(4.2±1.3),(4.3±1.1)和(8.5±1.7)mm/a的右旋走滑活动.但金沙江断裂目前基本不活动,红河断裂的活动性不强.龙门山一带没有发现明显的地壳活动,而其西北方向的活动带(龙日坝断裂)约有(5.1±1.2)mm/a的右旋走滑分量.川滇菱形块体内部的一些断裂表现出较强的活动性,其中理塘断裂左旋走滑速率为(4.4±1.3)mm/a,拉张速率(2.7±1.1)mm/a;玉农希断裂及其周边地区右旋剪切形变速率为(2.7±2.3)mm/a,地壳缩短速率(6.7±2.3)mm/a.丽江-小金河断裂中段活动性强于北段和南段,达到左旋走滑(5.4±1.2)mm/a,拉张(0.5±1.0)mm/a.与此同时,讨论了不同断裂锁定深度对结果的影响,并得到鲜水河断裂的锁定深度为15km,70%置信区间为11~19km.上述反演结果表明,研究区存在多条错动速率非常有限的活动断裂,将地壳分割成多个相互运动的地块,青藏高原的东向挤出通过这些断裂的活动被吸收和调整,而不是少数大型走滑断裂的快速走滑造成向东南方向的"逃逸".

A linked-fault-element model is employed to invert for contemporary slip rates along major active faults in the Sichuan-Yunnan region (96°–108°E, 21°–35°N) using the least squares method. The model is based on known fault geometry, and constrained by a GPS-derived horizontal velocity field. Our results support a model attributing the eastward extrusion of the Tibetan Plateau driven mainly by the north-northeastward indentation of the Indian plate into Tibet and the gravitational collapse of the plateau. Resisted by a relatively stable south China block, materials of the Sichuan-Yunnan region rotate clockwise around the eastern Himalayan tectonic syntaxis. During the process the Garzê-Yushu, Xianshuihe, Anninghe, Zemuhe, Daliangshan, and Xiaojiang faults, the southwest extension of the Xiaojiang fault, and the Daluo-Jinghong and Mae Chan faults constitute the northeast and east boundaries of the eastward extrusion, with their left slip rates being 0.3–14.7, 8.9–17.1, 5.1 ± 2.5, 2.8 ± 2.3, 7.1 ± 2.1, 9.4 ± 1.2, 10.1 ± 2.0, 7.3 ± 2.6, and 4.9 ± 3.0 mm/a respectively. The southwestern boundary consists of a widely distributed dextral transpressional zone other than a single fault. Right slip rates of 4.2 ± 1.3, 4.3 ± 1.1, and 8.5 ± 1.7 mm/a are detected across the Nanhua-Chuxiong-Jianshui, Wuliangshan, and Longling-Lancang faults. Crustal deformation across the Longmenshan fault is weak, with shortening rates of 1.4 ± 1.0 and 1.6 ± 1.3 mm/a across the Baoxing-Beichuan and Beichuan-Qingchuan segments. Northwest of the Longmenshan fault lies an active deformation zone (the Longriba fault) with 5.1±1.2 mm/a right slip across. Relatively large slip rates are detected across a few faults within the Sichuan-Yunnan block: 4.4±1.3 mm/a left slip and 2.7±1.1 mm/a shortening across the Litang fault, and 2.7±2.3 mm/a right-lateral shearing and 6.7±2.3 mm/a shortening across the Yunongxi fault and its surrounding regions. In conclusion, we find that the Sichuan-Yunnan region is divided into more than a dozen active micro-blocks by a large number of faults with relatively slow slip rates. The eastward extrusion of the Tibetan Plateau is absorbed and adjusted in the region mainly by these faults, other than a small number of large strike-slip faults with fast slip rates.

Based on the data of historical earthquakes and seismotectonic we analysised the parameters of seismogenic fault of the earthquakes more then MS 6.5 occurred in North of China since 1300 A.D..Using the earthquake parameters of Longyao,Haicheng,Bohai Sea and Tangshan earthquakes since 1968 A.D.We studied and developed the regression equations between the length of long axis of Ⅷ isoseismal curve and long axis of aftershork series as well as earthquake magnitude and the long axis of aftershork series.Using the long axis of aftershork series instead of the length of seismogenic fault,we gave the length of seismogenic fault of earthquake occurred in Huabei of China since 1300 A.D..On studying the data of explosion seismic sounding profile of crustal structure and tectonic,focal distribution of aftershork series,low velocity belts in the crust and tectonic of upcrust,basin's tectonic and distribution of Curie surface and distribution of known earthquake focal we implied the rupture width of seismogenic fault.Under some reasonable hypothesis we calculated the displacement of the seismogenic fault and the rakeangle on the fault plane.

甘肃筏子坝铜矿矿体赋存在喷发旋回晚期变质中基性—基性火山岩层向沉积岩层过渡部位,主含矿层为含铜磁铁石英岩;各类岩（矿）石物性差异明显,Cu、Zn、Mo、Co及Au、Ag主要成矿元素异常浓度分带明显;矿体上均有明显物化探异常;提出了地质-地球物理-地球化学综合找矿标志。

目前地震断层相互作用问题已引起地震学家的广泛关注.许多研究表明一条断层的破裂可以影响附近其他断层趋于破裂的进程,两条断层间的确切作用取决于它们的相对位置、破裂机制、错动量和介质力学性质.本研究给出了华北地区700年来由于长期构造加载及地震断层错动导致的累积库仑破裂应力变化(△CCFS)的演化过程.长期构造加载场由GPS观测得到的地壳平均应变率场给出.关于历史地震断层破裂参数的估算,根据的是华北地区有现代仪器记录的大震资料归算地震烈度与断层破裂长度、震级和地震矩的统计关系;根据地质调查得到的地震断层走向、倾角以及本地区的构造应力场方向估计滑动角.考虑粘弹性成层介质地壳模型,计算长期构造加载和地震形变(同震及震后介质粘弹性驰豫变形)造成的累积应力场变化.将累积应力场变化投影到后续地震断层面和滑动方向上得到△CCFS,并研究其对后续地震发生的触发作用.对1303年以来华北地区发生的49个M≥6.5地震研究结果表明:△CCFS对48个后续地震中的38个有触发作用,触发率达到79.2%.应用当今累积应力场变化于华北地区1303年～2003年发生的M≥5地震,我们发现触发率达到75.5%,于1976年以来发生的M≥5地震触发率达82.1%.未被触发的地震中有些是发生在断层破裂区附近的余震,很可能是由于历史地震破裂参量估计的误差落入影区中,若排除这些影响,触发率会更高.研究表明△CCFS与发生的后续地震有很好的相关性.当前△CCFS显著上升的地区包括渤海及其邻域地区、西秦岭北缘断裂带、张家口-渤海地震带西端和太原盆地,其地震危险性应引起重视.