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1.
Basement structural architecture and hydrocarbon conduit potential of polygonal faults in the Cooper‐Eromanga Basin,Australia 
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下载免费PDF全文 David Kulikowski Khalid Amrouch Dennis Cooke Michael Edward Gray 《Geophysical Prospecting》2018,66(2):366-396
A thorough and complete understanding of the structural geology and evolution of the Cooper‐Eromanga Basin has been hampered by low‐resolution seismic data that becomes particularly difficult to interpret below the thick Permian coal measures. As a result, researchers are tentative to interpret the basement fault architecture within the basin, which is largely undefined. To provide a better understanding of the basement fault geometry, all available two‐dimensional seismic lines together with 12 three‐dimensional seismic surveys were structurally interpreted with assistance from seismic attribute analysis. The Upper Cretaceous Cadna‐owie Formation and top Permian reflectors were analysed using a common seismic attribute technique (incoherency) that was used to infer the presence of faults that may have otherwise been overlooked. Detailed basement fault maps for each seismic survey were constructed and used in conjunction with two‐dimensional seismic data interpretation to produce a regional basement fault map. Large north‐northeast–south‐southwest‐striking sinistral strike–slip faults were identified within the Patchawarra Trough appearing to splay from the main northeast–southwest‐striking ridge. These sinistral north‐northeast–south‐southwest‐striking faults, together with field‐scale southeast–northwest‐striking dextral strike–slip faults, are optimally oriented to have potentially developed as a conjugated fault set under a south‐southeast–north‐northwest‐oriented strike–slip stress regime. Geomechanical modelling for a regionally extensive system of Cretaceous polygonal faults was performed to calculate the Leakage Factor and Dilation Tendency of individual faults. Faults that extend into Lower Cretaceous oil‐rich reservoirs with strikes of between 060°N and 140°N and a high to near‐vertical dip angle were identified to most likely be acting as conduits for the tertiary migration of hydrocarbons from known Lower Cretaceous hydrocarbon reservoirs into shallow Cretaceous sediments. This research provides valuable information on the regional basement fault architecture and a more detailed exploration target for the Cooper‐Eromanga Basin, which were previously not available in literature. 相似文献
2.
Similarities between strike-slip faults at different scales and a simple age determining method for active faults 总被引：1，自引：0，他引：1
Abstract Several differently scaled strike‐slip faults were examined. The faults shared many geometric features, such as secondary fractures and linkage structures (damage zones). Differences in fault style were not related to specific scale ranges. However, it was recognized that differences in style may occur in different tectonic settings (e.g. dilational/contractional relays or wall/linkage/tip zones), different locations along the master fault or different fault evolution stages. Fractal dimensions were compared for two faults (Gozo and San Andreas), which supports the idea of self‐similarity. Fractal dimensions for traces of faults and fractures of damage zones were higher (D ～1.35) than for the main fault traces (D ～1.005) because of increased complexity due to secondary faults and fractures. Based on the statistical analysis of another fault evolution study, single event movements in earthquake faults typically have a maximum earthquake slip : rupture length ratio of approximately 10?4, although this has only been established for large earthquake faults because of limited data. Most geological faults have a much higher maximum cumulative displacement : fault length ratio; that is, approximately 10?2 to 10?1 (e.g. Gozo, ～10?2; San Andreas, ～10?1). The final cumulative displacement on a fault is produced by accumulation of slip along ruptures. Hence, using the available information from earthquake faults, such as earthquake slip, recurrence interval, maximum cumulative displacement and fault length, the approximate age of active faults can be estimated. The lower limit of estimated active fault age is expressed with maximum cumulative displacement, earthquake slip and recurrence interval as T ? (dmax /u) · I(M). 相似文献
3.
Fault slip rate is one of the most important subjects in active tectonics research, which reveals the activity and seismic potential of a fault. Due to the improvement of dating precision with the development of dating methods, Holocene geological markers, even the young markers of thousands or hundreds of years old, are widely used in fault slip rate calculation. Usually, uncertainties from a single event and erosion of the accumulated offsets are involved in fault slip rate determination. Two types of uncertainties are related to a single event; the first is the time elapsed since the latest (the most recent) event; the second is the period since the formation of the geological marker to the occurrence of the first event. High‐slip‐rate faults are more sensitive to these uncertainties than low‐slip‐rate faults. In this study, we studied quantitatively the effects of a single event on fault slip rate following the three classic earthquake models: the characteristic earthquake, uniform slip and variable slip models. We suggest that the erosion of the accumulated offset–lateral erosion on a strike‐slip fault, should also be considered in fault slip estimation. Therefore, we propose a differential method to obtain a reliable fault slip rate. In the differential method, the slip rate is the ratio of offset differentials and corresponding age differentials between the older and younger terraces along strike‐slip faults. This kind of differential method could avoid the uncertainties from the first and latest events, as well as that from the lateral erosion. By applying the differential method, we got the revised slip rates of ∼5–10 mm/year on the Altyn Tagh and Kunlun faults. These low slip rates could fit previous geodetic and geological fault slip rates and shortening rates as well as the millennial recurrence intervals of strong earthquakes along the major segments of these faults. 相似文献
4.
Western Sichuan is among the most seismically active regions in southwestern China and is characterized by frequent strong (M 6.5) earthquakes, mainly along the Xianshuihe fault zone. Historical and instrumental seismicity show a temporal pattern of active periods separated by inactive ones, while in space a remarkable epicenter migration has been observed. During the last active period starting in 1893, the sinistral strike–slip Xianshuihe fault of 350 km total length, was entirely broken with the epicenters of successive strong earthquakes migrating along its strike. This pattern is investigated by resolving changes of Coulomb failure function (CFF) since 1893 and hence the evolution of the stress field in the area during the last 110 years. Coulomb stress changes were calculated assuming that earthquakes can be modeled as static dislocations in an elastic halfspace, and taking into account both the coseismic slip in strong (M 6.5) earthquakes and the slow tectonic stress buildup associated with major fault segments. The stress change calculations were performed for faults of strike, dip, and rake appropriate to the strong events. We evaluate whether these stress changes brought a given strong earthquake closer to, or sent it farther from, failure. It was found that all strong earthquakes, and moreover, the majority of smaller events for which reliable fault plane solutions are available, have occurred on stress–enhanced fault segments providing a convincing case in which Coulomb stress modeling gives insight into the temporal and spatial manifestation of seismic activity. We extend the stress calculations to the year 2025 and provide an assessment for future seismic hazard by identifying the fault segments that are possible sites of future strong earthquakes. 相似文献
5.
根据塞积群理论导出了走滑断层两端点固定时位移场随位置的不均匀分布解析表示关系,分析和讨论了断层上不同位置的位移场分布特征, 采用新导出的断层滑动不均匀分布公式对地面的水平位移场和垂直位移场进行了数值模拟计算,并与传统的Okada 位错模型在理论和计算结果上进行了对比分析.理论和计算结果分析表明：断层滑动不均匀分布公式是Okada位错模型在一定条件下理论上的扩展,而Okada位错模型是走滑不均匀公式的零阶近似;断层滑动不均匀分布公式与Okada 位错模型计算的地面位移场在走滑方向、垂直于断层走向和垂直于地面方向的近场变形差异最大在50%至65%之间,而最小差异在1%以内. 相似文献
6.
Ｃｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆｔｅｃｔｏｎｉｃｄｅｆｏｒｍａｔｉｏｎｆｉｅｌｄａｂｏｕｔｓｔｒｉｋｅ－ｓｌｉｐｅａｒｔｈｑｕａｋｅ－ｇｅｎｅｒａｔｉｎｇｓｔｒｕｃｔｕｒｅｉｎｔｈｅＣｈｉｎｅｓｅｍａｉｎｌａｎｄ环文林，张晓东，宋昭仪Ｗｅｎ－Ｌｉｎ... 相似文献
7.
A closed-form analytic solution for the displacement and stress field due to a trapezoidal type of nonuniform slip along a strike slip fault is obtained by following Steketee’s method of integration. A set of displacement and stress contours are plotted and compared with the corresponding cases of uniform slip. A possible explanation of the equidistance distribution of strike slip faults and its relation to the amount of slip and the dimensions of the fault are shown. 相似文献
8.
平行走滑断层相互作用的粘弹模型和减震作用 总被引：6，自引：0，他引：6
研究了二维粘弹性介质中平行走滑断层的相互力学作用及其地震活动性的影响。当一条断层发生滑动,将导致平行断层面上剪切应力减小,因此,可能推迟平行断层发生滑动,推迟时间在几年至几百年的范围内,这取决于发生滑动的断层与平行断层之间的距离,以及平行断层自身应力积累孕育地震过程经历的时间。 相似文献
9.
The Chi‐Chi earthquake (MW = 7.6) took place in central western Taiwan in 1999. The earthquake caused reactivation of the Chelungpu Fault and resulted in 100‐km‐long surface ruptures. The fault strikes mostly north–south to NNE–SSW; however, the northern tip of the southern segment of the surface ruptures rotates clockwise to define an east–west trend, then jumps to a shorter NNW‐trending rupture. The largest vertical displacement is recorded in the Shihkang area of the Shihkang–Shangchi Fault Zone, where vertical slips are up to 8–10 m. The Shihkang–Shangchi Fault Zone displays a complex fault pattern as a linkage damage zone between two fault segments with the greatest concentration of faults and fractures. Our new interpretation, based on recent published geometric, kinematic, and geophysical studies on the Chi‐Chi earthquake fault, suggests that the Shihkang–Shangchi Fault Zone is not a simple termination zone, but may be an ‘overstep zone’ or a ‘transfer zone’. Slip analysis along the surface ruptures indicates that they are composed of three fault segments and the amount of slip partly depends on the intersection angle between slip direction and fault strike. Our numerical modeling for the area indicates that Coulomb stress changes are mainly concentrated on tips and bends of the surface ruptures. Slip patterns indicate that the fault propagates toward the northeast. Therefore, this study suggests high potential for future earthquake activity along the unruptured Shangchi segment. Hence, future geohazard studies should focus on the Shangchi segment to evaluate potential earthquakes, determine recurrence intervals, and reduce future earthquake hazards. 相似文献
10.
利用川滇地区1991-1999年的高精度GPS观测处理结果,采用稳健 - 贝叶斯最小二乘算法与多断裂位错模型,分析研究了川滇菱形块体主要边界运动的定量模型.反演分析表明:川西鲜水河断裂带和安宁河断裂带的左旋走滑运动速率约30mm/a,倾滑运动(逆断层)速率分别约9-11mm/a;滇西红河断裂带、程海断裂带、鹤庆 - 洱源断裂带的走滑运动(分别为右旋、左旋、左旋)速率分别约、11、13mm/a,倾滑运动(正断层)速率分别约16、24、16mm/a;如将其视为弹性应力应变积累,则各断层每年有相当于6级左右的地震能量积累.依据上述反演结果,模拟了区域主要断层运动引起的水平位移、应变速率场图像,显示了边界断裂及其之间的相互作用. 相似文献
11.
运用震源位错模型, 分析矩形垂直断层及倾斜断层走向滑动和倾向滑动的近场地震动场，以地表地震动的傅立叶振幅谱比为参量考察断层附近地震动空间分布的特点. 结果表明, 断层附近的地震动强度主要受近旁子断层的控制，高强度的地震动分布在紧靠断层两侧有限的带状区域内，长周期分量受断层破裂传播方向性的影响. 走向滑动的方向性影响主要表现在垂直于断层走向的分量，倾向滑动则表现在平行于断层走向的分量，且深震在地面上引起的地震动强度分布比浅震要平缓，影响范围宽. 倾斜断层产生的地震动有明显的上盘效应，空间分布不对称，与观测结果相符. 最后给出了断层附近近场地震动强度分布拟合函数的表达式，并与美国的1997统一建筑规范规定的近场因子作了比较. 相似文献
12.
We investigate the evolution of wear and friction along experimental faults composed of solid rock blocks. This evolution is analyzed through shear experiments along five rock types, and the experiments were conducted in a rotary apparatus at slip velocities of 0.002–0.97 m/s, slip distances from a few millimeters to tens of meters, and normal stress of 0.25–6.9 MPa. The wear and friction measurements and fault surface observations revealed three evolution phases: A) An initial stage (slip distances <50 mm) of wear by failure of isolated asperities associated with roughening of the fault surface; B) a running-in stage of slip distances of 1–3 m with intense wear-rate, failure of many asperities, and simultaneous reduction of the friction coefficient and wear-rate; and C) a steady-state stage that initiates when the fault surface is covered by a gouge layer, and during which both wear-rate and friction coefficient maintain quasi-constant, low levels. While these evolution stages are clearly recognizable for experimental faults made from bare rock blocks, our analysis suggests that natural faults “bypass” the first two stages and slip at gouge-controlled steady-state conditions. 相似文献
13.
利用广东新丰江锡场2012和2013年2次MS4.8地震震中附近的2009年1月至2015年6月精定位小震资料,依据小震丛集发生在大震断层面及附近的原则,采用模拟退火算法和高斯-牛顿算法相结合的方法,反演得到了锡场附近2条相交断层的详细参数及地理分布。NEE向断层F1的走向为78.5°,倾角为87.7°,长度约8.2km,以右旋走滑错动为主;NW向断层F2的走向为137.3°,倾角为87.9°,长度约5.9km,以左旋走滑错动为主。用断层附近ML3以上地震的震源机制解证明反演结果是可靠的,并由2次4.8级地震的震源机制解判断出各自的发震断层。 相似文献
14.
2008年5月12日发生在四川汶川的大地震造成映秀—北川断裂和灌县—江油断裂同时破裂,分别形成了240多公里和70多公里的地表破裂带.本文以GPS观测获得的同震位移场为约束,反演地震破裂的空间分布.反演结果显示映秀—北川主破裂带倾向北西,沿破裂带的走向从南到北倾角逐渐变大,破裂断层的平均宽度在10~18 km左右.破裂断层的错动在南段以逆冲为主,在北段走滑分量逐步加大,右旋走滑成为断层破裂的主要特征.断层破裂最大段落错动量分别达到了7.8 m和7.4 m,恰好对应这次地震中地表破坏最为严重的映秀和北川地区.本次地震释放地震矩6.70×1020N·m,相应矩震级Mw=7.9. 相似文献
15.
Recognition of shear heating on a long‐lived major fault using Raman carbonaceous material thermometry: implications for strength and displacement history of the MTL,SW Japan 下载免费PDF全文
下载免费PDF全文 The extent to which movement on major faults causes long term shear heating is a contentious issue and an important aspect in the debate about the strength of major faults in the crust. Comparing the results of experimental work on the kinetics of crystallization of carbonaceous material with results of thermal modeling show that the Raman carbonaceous material (CM) geothermometer is well suited to studying shear heating on geological time scales in suitable lithologies exposed around exhumed major fault zones. The Median Tectonic Line (MTL), SW Japan, is the largest on‐land fault in Japan with a length of > 800 km. Application of Raman CM thermometry to pelitic schist adjacent to the fault reveals the presence of a rise in peak temperature of around 60 °C over a distance of around 150 m perpendicular to the MTL fault plane. The spatial association of this thermal anomaly with the fault implies it is due to shear heating. Thermal modeling shows the recorded thermal anomaly and steep temperature gradient is compatible with very high rates of displacement over time scales of a few thousand years. However, the implied displacement rates lie outside those generally observed. An alternative explanation is that an originally broader thermal anomaly that developed during strike slip faulting was shortened due to the effects of normal faulting. Constraints on displacement rate, width of the original anomaly, duration of heating and peak temperature imply a coefficient of friction, μ, greater than 0.4. 相似文献
16.
Internal structures and high-velocity frictional properties of a bedding-parallel carbonate fault at Xiaojiaqiao outcrop activated by the 2008 Wenchuan earthquake 下载免费PDF全文
下载免费PDF全文 Linfeng Hou Shengli Ma Toshihiko Shimamoto Jianye Chen Lu Yao Xiaosong Yang Yuji Okimura 《地震科学（英文版）》2012,25(3):197-217
This paper reports internal structures of a bedding-parallel fault in Permian limestone at Xiaojiaqiao outcrop that was moved by about 0.5 m during the 2008 MW7.9 Wenchuan earthquake. The fault is located about 3 km to the south from the middle part of Yingxiu-Beichuan fault, a major fault in the Longmenshan fault system that was moved during the earthquake. The outcrop is also located at Anxian transfer zone between the northern and central segments of Yingxiu-Beichuan fault where fault system is complex. Thus the fault is an example of subsidiary faults activated by Wenchuan earthquake. The fault has a strike of 243° or N63°E and a dip of 38°NW and is nearly optimally oriented for thrust motion, in contrast to high-angle coseismic faults at most places. Surface outcrop and two shallow drilling studies reveal that the fault zone is several centimeters wide at most and that the coseismic slip zone during Wenchuan earthquake is about 1 mm thick. Fault zone contains foliated cataclasite, fault breccia, black gouge and yellowish gouge. Many clasts of foliated cataclasite and black gouge contained in fault breccia indicate multiple slip events along this fault. But fossils on both sides of fault do not indicate clear age difference and overall displacement along this fault should not be large. We also report results from high-velocity friction experiments conducted on yellowish gouge from the fault zone using a rotary shear low to high-velocity frictional testing apparatus. Dry experiments at normal stresses of 0.4 to 1.8 MPa and at slip rates of 0.08 to 1.35 m/s reveal dramatic slip weakening from the peak friction coefficient of around 0.6 to very low steady-state friction coefficient of 0.1-0.2. Slip weakening parameters of this carbonate fault zone are similar to those of clayey fault gouge from Yingxiu-Beichuan fault at Hongkou outcrop and from Pingxi fault zone. Our experimental result will provide a condition for triggering movement of subsidiary faults or off-fault damage during a large earthquake. 相似文献
17.
通过卫星影像解译、野外实地调查与地质填图,对滇西南地区黑河断裂中西段晚第四纪构造活动特征进行了研究.结果表明,黑河断裂为一条规模较大的区域性活动断裂带,西起沧源县南,向东南止于澜沧江断裂,全长约168 km,走向280°～310°.该断裂晚第四纪新活动性具有一定的差异性和分段性.根据其几何结构、最新活动性及1988年澜沧7.6级地震破裂带特征,可将黑河断裂从西向东划分为沧源-木戛、木戛-南代和南代-勐往三条次级断裂段.其中的中、西段长约88 km,全新世活动显著,活动性质以右旋走滑为主.沿断裂形成了丰富的断错地貌现象.西段断裂的最新活动断错了全新世晚期地层;中段是1988年澜沧7.6级地震的发震断裂之一.根据对断错冲沟的测量和年代测试,得到其全新世以来右旋滑动速率为(3.54±0.78)mm/a,与区域上其它断裂的滑动速率大致相当,反映了其区域构造活动的整体性和协调性. 相似文献
18.
Yongge Wan Zheng-kang Shen Min Wang Yuehua Zeng Jichao Huang Xiang Li Huawei Cui Xiwei Gao 《地震科学（英文版）》2015,28(3):187-195
We analyze co-seismic displacement field of the 26 December 2004, giant Sumatra–Andaman earthquake derived from Global Position System observations,geological vertical measurement of coral head, and pivot line observed through remote sensing. Using the co-seismic displacement field and AK135 spherical layered Earth model, we invert co-seismic slip distribution along the seismic fault. We also search the best fault geometry model to fit the observed data. Assuming that the dip angle linearly increases in downward direction, the postfit residual variation of the inversed geometry model with dip angles linearly changing along fault strike are plotted. The geometry model with local minimum misfits is the one with dip angle linearly increasing along strike from 4.3oin top southernmost patch to 4.5oin top northernmost path and dip angle linearly increased. By using the fault shape and geodetic co-seismic data, we estimate the slip distribution on the curved fault. Our result shows that the earthquake ruptured *200-km width down to a depth of about 60 km.0.5–12.5 m of thrust slip is resolved with the largest slip centered around the central section of the rupture zone78N–108N in latitude. The estimated seismic moment is8.2 9 1022 N m, which is larger than estimation from the centroid moment magnitude(4.0 9 1022 N m), and smaller than estimation from normal-mode oscillation data modeling(1.0 9 1023 N m). 相似文献
19.
The earthquake was modeled using regional broad-band stations in Greece (epicentral distances up to 340 km). Inversion of the amplitude spectra of complete waveforms (0.05–0.08 Hz), later confirmed by the forward waveform modeling, provided strike = 150°, dip = 70°, rake = 10°, scalar moment M
o = 4.1e18 Nm, and depth of 8 km. As the aftershock distribution had the same strike, the earthquake was interpreted as a left-lateral strike slip. The fault length was estimated by combining observed mainshock spectra and synthetic spectra of a weak event, representing impulse response of the medium. This gave the fault length estimate of 16 to 24 km. Similar results were obtained by means of a true M
w = 5 aftershock. The waveform modeling (0.05–0.20 Hz) was performed for the 20 × 10 km finite-extent fault, with a homogenous slip of 0.63 m. It showed that the rupture propagation along the 150° strike was predominantly unilateral, from NW to SE. 相似文献
20.
Onur Tan Eleftheria E. Papadimitriou Zumer Pabucçu Vassilis Karakostas Ahmet Yörük Kostas Leptokaropoulos 《Acta Geophysica》2014,62(6):1283-1309
A detailed investigation of microseismicity and fault plane solutions are used to determine the current tectonic activity of the prominent zone of seismicity near Samos Island and Kusadasi Bay. The activation of fault populations in this complex strike-slip and normal faulting system was investigated by using several thousand accurate earthquake locations obtained by applying a double-difference location method and waveform cross-correlation, appropriate for areas with relatively small seismogenic structures. The fault plane solutions, determined by both moment tensor waveform inversions and P-wave first motion polarities, reveal a clear NS trending extension direction, for strike slip, oblique normal and normal faults. The geometry of each segment is quite simple and indicates planar dislocations gently dipping with an average dip of 40–45°, maintaining a constant dip through the entire seismogenic layer, down to 15 km depth. 相似文献