共查询到20条相似文献，搜索用时 859 毫秒
1.
Naoyuki Kato Takashi Satoh Xinglin Lei Kiyohiko Yamamoto Tomowo Hirasawa 《Tectonophysics》1999,310(1-4):81-99
An experimental study of stick-slip is performed to examine the effect of a fault bend on the dynamic rupture propagation process. A granite sample used in the experiment has a pre-cut fault that is artificially bent by an angle of 5.6° at the center of the fault along strike, and accordingly the fault consists of two fault segments. The rupture propagation process during stick-slip instability is investigated by analyzing the records of shear strain and relative displacement measured with strain gauge sensors together with the hypocenters of AE (acoustic emission) events detected with piezoelectric transducers. The observed rupture propagation process of typical stick-slip events is as follows. (1) The dynamic rupture started on a fault segment is stopped near the fault bend. (2) The rupture propagation is restarted near the bend on the other fault segment 10.8 ms to 3.5 s after the stop of the first rupture. The delay time of the second rupture decreases with an increase in the slip amount of the first rupture or a decrease in the normal stress acting on the fault segment where the second rupture started. (3) The restarted rupture is not arrested by the presence of a fault bend, and slip occurs over the entire fault. We theoretically analyze the stress concentration near the fault bend to find that the normal stress produced by the preceding slip near the fault bend plays an important part in controlling the rupture propagation. A numerical simulation based on a rate- and state-dependent friction law is performed to interpret physically the retarded rupture in the experiment. The observed time interval of 10.8 ms to 3.5 s between the first rupture and the second is explained by the numerical simulation, suggesting that the rate- and state-dependence of rock friction is a possible mechanism for the retarded rupture on the fault. 相似文献
2.
Ahmadreza Hedayat Laura J. Pyrak-Nolte Antonio Bobet 《Rock Mechanics and Rock Engineering》2014,47(5):1575-1587
Seismic wave transmission and digital image correlation (DIC) are employed to study slip processes along frictional discontinuities. A series of biaxial compression experiments are performed on gypsum specimens with non-homogeneous contact surfaces. The specimens are composed of two blocks with perfectly mated contact surfaces with a smooth surface with low frictional strength on the upper half and a rough surface with high frictional strength on the lower half. Compressional, P, and shear, S, wave pulses were transmitted through the discontinuity while digital images of the specimen surface were acquired during the test. A distinct peak in the amplitude of transmitted wave occurs prior to the peak shear strength and is considered a “precursor” to the failure. Precursors indicate that slip initiates from the smooth surface and extends to the rough surface as the shear load is increased. From the DIC data, slip is identified as a jump in the displacement field along the fracture that initiates from the smooth surface and propagates to the rough surface. Precursors are associated with an increase in the rate of slip across the discontinuity and are a measure of the reduction in the fracture shear stiffness. 相似文献
3.
V. V. Adushkin G. G. Kocharyan A. A. Ostapchuk D. V. Pavlov 《Doklady Earth Sciences》2016,470(2):1100-1103
A new method for controlling the dynamic shear stiffness of interblock contact during stick-slip is proposed. This method enables us to reveal changes in the mechanical properties of the contact long before the macroscopic slip will be recorded. In the experiments conducted, the time of precursor manifestation was about 1/3 of the duration of the “seismic cycle.” 相似文献
4.
Howard R. Williams 《Tectonophysics》1987,140(2-4):327-331
Differential shear stresses acting along or adjacent to a non-planar fault surface or shear zone may cause uneven acceleration during slip. Alternatively, at the initiating and closing stages of motion of parts of a stick-slip fault, localised shear stresses may be variable. Stress variation of this nature causes zones of relative compression and tension, especially close to the “stick” zones on the fault. In fissile rocks adjacent to the fault, kink bands form in zones of local relative compression, while stratal extension features such as veins, fractures and extensional crenulations might be expected in the corresponding zones of relative tension. Repetitive motion on the fault should therefore cause the development of a suite of kink bands superimposed on each other and on any complementary extensional structures. Field evidence indicates that the extensional structures are not developed to the same extent as the kinks, perhaps due to ductile flow during layer-parallel extension of phyllosilicate rocks.
The advantages of this model are that it does not require bulk shortening of the shear zone relative to the enclosing less strained rocks, nor does it depend on complex stress orientation changes. 相似文献
5.
To investigate the physical processes operating in active fault zones, we conduct analogue laboratory experiments where we track the morphological and mechanical evolution of an interface during slip. Our laboratory friction experiments consist of a halite (NaCl) slider held under constant normal load that is dragged across a coarse sandpaper substrate. This set-up is a surrogate for a fault surface, where brittle and plastic deformation mechanisms operate simultaneously during sliding. Surface morphology evolution, frictional resistance and infra-red emission are recorded with cumulative slip. After experiments, we characterize the roughness developed on slid surfaces, to nanometer resolution, using white light interferometry. We directly observe the formation of deformation features, such as slip parallel linear striations, as well as deformation products or gouge. The striations are often associated with marginal ridges of positive relief suggesting sideways transport of gouge products in the plane of the slip surface in a snow-plough-like fashion. Deeper striations are commonly bounded by triangular brittle fractures that fragment the salt surface and efficiently generate a breccia or gouge. Experiments with an abundance of gouge at the sliding interface have reduced shear resistance compared to bare surfaces and we show that friction is reduced with cumulative slip as gouge accumulates from initially bare surfaces. The relative importance of these deformation mechanisms may influence gouge production rate, fault surface roughness evolution, as well as mechanical behavior. Finally, our experimental results are linked to Nature by comparing the experimental surfaces to an actual fault surface, whose striated morphology has been characterized to centimeter resolution using a laser scanner. It is observed that both the stress field and the energy dissipation are heterogeneous at all scales during the maturation of the interface with cumulative slip. Importantly, we show that the formation of striations on fault planes by mechanical abrasion involves transport of gouge products in the fault plane not only along the slip direction, but also perpendicular to it. 相似文献
6.
Some recent Chinese observations on precursory crustal movements detected by geodetic measurements such as short-range levelling or base-line survey across the active fault corroborate the three gamma phases model of Fujita and Fujii: Gamma 1 phase is pre-slip along the imminent faulting, gamma 2 is coseismic slip and gamma 3 is post-slip along the main or subsidiary faulting after an earthquake. Typical of these are the results of short-range levelling across the earthquake fault that ruptured during the 1976 Tangshan earthquake (Ms = 7.8). Associated with the occurrence of the Tangshan earthquake or the subsequent Ninghe earthquake (Ms = 6.9), remarkable gamma 2 phases were observed. At this same location abnormal gamma 1 or gamma 3 phases were detected from the Lulong 1982 earthquake (Ms = 6.2) that originated from the north end of the Tangshan Fault and was one of the aftershocks of the Tangshan earthquake. These phases are interpreted by analogy with the recent experimental results of stick-slip motion of the frictional sliding of rock. 相似文献
7.
Flexural slip folds are distinctive of mixed continuous-discontinuous deformation in the upper crust, as folding is accommodated by continuous bending of layers and localized, discontinuous slip along layer interfaces. The mechanism of localized, layer-parallel slip and the stress and fluid pressure conditions at which flexural slip occurs are therefore distinctive of shear localization during distributed deformation. In the Prince Albert Formation mudstone sequence of the Karoo Basin, the foreland basin to the Cape Fold Belt, folds are well developed and associated with incrementally developed bedding-parallel quartz veins with slickenfibers oriented perpendicular to fold hinge lines, locally cross-cutting axial planar cleavage, and showing hanging wall motion toward the fold hinge. Bedding-parallel slickenfiber-coated veins dip at angles from 18° to 83°, implying that late increments of bedding-parallel shear occurred along unfavorably oriented planes. The local presence of tensile veins, in mutually cross-cutting relationship with bedding-parallel, slickenfiber-coated veins, indicate local fluid pressures in excess of the least compressive stress.Slickenfiber vein microstructures include a range of quartz morphologies, dominantly blocky to elongate-blocky, but in places euhedral to subhedral; the veins are commonly laminated, with layers of quartz separated by bedding-parallel slip surfaces characterized by a quartz-phyllosilicate cataclasite. Crack-seal bands imply incremental slickenfiber growth, in increments from tens of micrometers to a few millimeters, in some places, whereas other vein layers lack evidence for incremental growth and likely formed in single slip events. Single slip events, however, also involved quartz growth into open space, and are inferred to have formed by stick-slip faulting. Overall, therefore, flexural slip in this location involved bedding-parallel faulting, along progressively misoriented weak planes, with a range of slip increments. 相似文献
8.
We have performed physical modeling of stick-slip on a large fault in the elastic-viscous-plastic model. It was found that, after each full activation, slips on the fault took place on its particular segments and evolved with time in a regular manner. This evolution is divided into the regressive and progressive phases. In the former phase, against the background of stress relaxation, the segment structure of the fault gradually disappears owing to the directed partitioning of larger segments into smaller ones, with some of them attaining a passive state. With the onset of the progressive phase, the decrease in stresses changes to increase. As stresses increase, some active segments reach a critical density and then decrease owing to the growth of smaller segments and their merging to form larger ones. The mean and total lengths of the recurrence graph, as well as its angle (β-value), increase as this process evolves. 相似文献
9.
《Journal of Structural Geology》1997,19(6):835-847
Fracture mechanics theory and field observations together indicate that the shear stress on many faults is non-uniform when they slip. If the shear stress were uniform, then: (a) a physically implausible singular stress concentration theoretically would develop at a fault end; and (b) a single curved ‘tail fracture’ should open up at the end of every fault trace, intersecting the fault at approximately 70 °. Tail fractures along many small faults instead range in number, commonly form behind fault trace ends, have nearly straight traces and intersect a fault at angles less than 50 °. A ‘cohesive zone’, in which the shear stress is elevated near the fault end, can eliminate the stress singularity and can account for the observed orientation, shape, and distribution of tail fractures. Cohesive zones also should cause a fault to bend. If the cohesive zone shear stress were uniform, then the distance from the fault end to the bend gives the cohesive zone length. The nearly straight traces of the tail fractures and the small bends observed near some fault ends implies that the faults slipped with low stress drops, less than 10% of the ambient fault-parallel shear stress. 相似文献
10.
Toshihiko Shimamoto 《Tectonophysics》1985,119(1-4)
Seismicity, deformation, state of stress, and abundance of fluids along subducting plate boundaries are reviewed, and the origin of large or great thrust-type earthquakes is discussed based on the recent experimental results on the slip behavior of halite and serpentine gouges.Shallow subducting plate boundaries above 20–25 km in depth are characterized by low seismicity, low tectonic stress, inter-plate decoupling, ductile deformation associated with the formation of metamorphic schistosity (except at very shallow depths), metamorphism suggesting solution processes on massive scale, and presence of abundant H2O. It is argued that these unique features are due to pressure-solution processes, to high fluid pressure, to low strength and stable behavior of clayey sediments under wet environments, and/or to the deformation of soft, unconsolidated sediments at very shallow depths. The low seismicity in this zone is in marked contrast with major strike-slip faults along which large earthquakes occur at depths shallower than 15–20 km. It is emphasized that these unique features are expected only for restricted regions where there is constant supply of H2O due to progressive metamorphism or where fluids in the rocks are trapped and cannot escape to the surface.Large or great thrust-type earthquakes in subduction zones initiate at depths of 30–50 km, below the shallow decoupled zone. In this focal depth range, the supply of H2O during progressive metamorphism perhaps diminishes downwards, the overriding and subducting plates are coupled and stick to each other during much of the inter-seismic period, and the resistance to slip (or shear stress) is presumably high. It is suggested that these earthquakes begin to occur at a depth where the plate-boundary zone becomes fairly dry. Deformation at these depths appears to be predominantly ductile, so that the earthquakes cannot be regarded simply as a brittle phenomenon. (1) Creep instability i.e., instability associated with plastic deformation, and (2) dehydration-induced instability are the most likely mechanisms for initiating the earthquakes, and both have some experimental support. Stick-slip of halite gouge while undergoing ductile deformation primarily by intracrystalline gliding is described and discussed as a supporting evidence for (1). Shear resistance of halite gouge increases with increasing confining pressure in stick-slip regimes. Hence the observed stick-slip may be a semi-brittle phenomenon with respect to the pressure dependence of the shear resistance, although the deformation texture cannot be distinguished from that formed by pressure-insensitive flow. Serpentine gouge exhibits violent stick-slip upon its decomposition under dry, not wet, environments, supporting the mechanism (2) above. Exact mechanisms which lead to the unstable fault motion are poorly understood as yet, but stick-slip of both halite and serpentine gouges is recognized only when the slip-rate dependence of friction is negative i.e., lower friction at faster slip rate, consistent with the theoretical prediction of Rice and Ruina (1983). There is a possibility that the thrust-type earthquakes can be explained essentially within the framework of fault constitutive laws developed by Dieterich (1979) and Ruina (1983). 相似文献
11.
A common problem encountered in studies of gouge-bearing natural faults is the difficulty of ascertaining whether the observed gouge was sheared seismically or aseismically; this problem arises because of the scarcity of indicators of fault slip rates for gouge. Recently, clay–clast aggregates (CCAs; a CCA comprises a clastic core mantled by a rim of ultrafine particles) were proposed as a possible indicator of seismic slip in gouge, on the basis of shear experiments on gouge at seismic slip rates. To examine the processes and conditions of CCA formation, we conducted rotary shear experiments on quartz and quartz–bentonite gouges under normal stresses (0.3–3.0 MPa) and slip rates (0.0005–1.3 m s−1), and in both room-humidity (room-dry) and water-saturated (wet) conditions. We found that CCAs could be produced in room-dry gouges even at the lowest slip rates, which are considerably slower than actual seismic slip rates. This finding demonstrates that thermal pressurization and fluidization at elevated temperature during seismic slip are not necessarily needed for the formation of CCAs, contrary to previous views. Given the occurrence of CCAs over a wide range of slip rates, we suggest that the presence of CCAs is not an unequivocal indicator of fault slip at seismic slip rates. 相似文献
12.
准噶尔盆地南缘断裂带显微构造特征与活动时代 总被引：1，自引：0，他引：1
对准噶尔盆地南缘霍尔果斯-玛纳斯-吐谷鲁逆断裂带中的断层泥和构造岩显微构造进行了研究,并对断裂带中的石膏、石英脉和断层泥进行了ESR测年。显微构造研究表明,断裂带至少经历了3期构造变形,断层泥和石英碎粒中既发育有线状擦痕、阶步等粘滑活动显微构造,也发育有剪切滑动、定向排列等蠕滑活动变形现象。ESR测年结果显示,霍尔果斯-玛纳斯-吐谷鲁逆断裂带形成于1.5Ma前,在0.4~1.0 Ma和0.08~0.12 Ma期间进行了二次再调整。断裂活动时间与青藏高原阶段性隆升的时间一致,说明准噶尔盆地南缘霍尔果斯-玛纳斯-吐谷鲁逆断裂带的形成与青藏高原的隆升过程密切相关。 相似文献
13.
We have analysed the earthquake sequence occurred at Campi Flegrei during an unrest episode of strong ground uplift and seismicity, occurred in the period 1982–1984. The maximum magnitude of these events was about 4. Both earthquake occurrence and ground deformation have been interpreted in terms of the role played by a ring fault system, inward dipping, related to phenomena of caldera collapse and resurgence. Earthquakes are of mixed strike-slip and normal fault type. They show a dip movement opposite to the static ground deformation. The rising of the internal block with respect to the zone external to the ring fault, as observed by ground deformation, should cause thrust fault slip on the fracture system, whereas a normal fault dip component is observed. The simulation of the stress field generated by overpressure in a magma chamber in presence of lateral discontinuities, as performed by a boundary element method, allows to hypothesise that reverse fault slip on the ring fault is mainly aseismic, and such aseismic movement is able to focus normal fault shear stress along the lateral discontinuities. Aseismic slip on the ring fault in response to static deformation is also supported by the low amount of seismic moment released (M0 ≅ 1015 Nm), about two orders of magnitude lower than expected from the shear slip on the discontinuities needed to accomplish the total static surface deformation (1.8 m). Such results have been compared with observations at Rabaul caldera, during a similar unrest episode. In such area, the seismic moment release is in good agreement with shear slip produced on a system of outward dipping ring faults, and seismicity is much more focused on the fault structures. The comparison between the two areas shed new light about the dynamics of earthquakes in calderas, as due to the role of bordering ring fault systems. 相似文献
14.
Seismic events can take place due to the interaction of stress waves induced by stope production blasts with faults located in close proximity to stopes. The occurrence of such seismic events needs to be controlled to ensure the safety of the mine operators and the underground mine workings. This paper presents the results of a dynamic numerical modelling study of fault slip induced by stress waves resulting from stope production blasts. First, the calibration of a numerical model having a single blast hole is performed using a charge weight scaling law to determine blast pressure and damping coefficient of the rockmass. Subsequently, a numerical model of a typical Canadian metal mine encompassing a fault parallel to a tabular ore deposit is constructed, and the simulation of stope extraction sequence is carried out with static analyses until the fault exhibits slip burst conditions. At that point, the dynamic analysis begins by applying the calibrated blast pressure to the stope wall in the form of velocities generated by the blast holes. It is shown from the results obtained from the dynamic analysis that the stress waves reflected on the fault create a drop of normal stresses acting on the fault, which produces a reduction in shear stresses while resulting in fault slip. The influence of blast sequences on the behaviour of the fault is also examined assuming several types of blast sequences. Comparison of the blast sequence simulation results indicates that performing simultaneous blasts symmetrically induces the same level of seismic events as separate blasts, although seismic energy is more rapidly released when blasts are performed symmetrically. On the other hand when nine blast holes are blasted simultaneously, a large seismic event is induced, compared to the other two blasts. It is concluded that the separate blasts might be employed under the adopted geological conditions. The developed methodology and procedure to arrive at an ideal blast sequence can be applied to other mines where faults are found in the vicinity of stopes. 相似文献
15.
通过选取南黄海盆地中部隆起内部地震反射清晰、构造特征明显的典型地震剖面,开展精细的构造解释,系统梳理了南黄海盆地中部隆起的构造样式特征,识别出挤压（滑脱、高角度逆冲、对冲/背冲）、走滑（正花状、y字型）、伸展（铲式正断层）等多种构造组合样式.首次提出在中部隆起内部发育2条NW-SE向走滑断层.在此基础上,结合区域应力场特征和深部地球动力学背景,明确了中部隆起构造样式的发育期次、成因机制和构造演化历程.研究结果表明:（1）滑脱构造主要位于中部隆起北部,滑脱面位于志留系底部的泥页岩.滑脱构造应力机制来源于三叠纪末印支运动时期华北板块与下扬子板块之间的碰撞造山作用;（2）高角度逆冲主要位于中部隆起南部,其应力机制来源于早侏罗世燕山运动早期,古太平洋板块初始高速、低角度NW向俯冲;（3）走滑断层主要表现为具有压扭特征的正花状构造,位于中部隆起东南部、中西部,对应于早白垩世时期,古太平洋板块低角度俯冲由NW向转变为NNW向引起的左旋剪切作用,中国东部郯庐断裂在该时期亦表现为左旋剪切特征;（4）伸展正断表现为铲式正断层特征,发育在中部隆起南北边界,即在中部隆起与南黄海盆地南部坳陷、北部坳陷的接触部位,对应于晚白垩世燕山运动晚期,古太平洋板块由低角度俯冲转为高角度俯冲,此时中国东部构造应力体制经历着由挤压向拉张的转换. 相似文献
16.
本文利用新的有限元方法研究了铲状正断层带在非均匀应力场下错动引起的位移场和应力场。研究发现：① 铲状正断层错动引起的断层面上的最大错距不是发生在地表,而是发生地表下面断层的中部;② 地表面最大水平位移和垂直位移都不是发生在地表断层上,而是发生在偏离断层一定距离的地方;③ 铲状正断层错动会在地表附近产生两个破裂区,一个在地表断层附近,一个在远离断层的上盘地表附近,这两个区与野外观测到的次生正断层区一致;④ 断层错动的应力降在断层内不是均匀的,最大值也是位于断层中部。 相似文献
17.
Michele Dragoni 《地学学报》1992,4(4):501-508
A model is proposed for studying the mechanical behaviour of faults during their interseismic periods. The model considers a plane fault surface in an elastic medium, subject to a uniform shear stress which increases slowly with time. A1-D friction distribution is assumed on the fault, characterized by asperities and a weaker zone. The traction vector on the fault plane has an arbitrary orientation: in particular, it can be nonperpendicular to the asperity borders. Aseismic fault slip takes place when the applied stress exceeds the frictional resistance: slip starts in weak zones and is confined by asperities, where it propagates at increasing velocity. Propagation into asperities is characterized by a dislocation front, advancing perpendicularly to the asperity border. Fault slip does not take prate in the direction of traction, except when traction is perpendicular or parallel to the asperity border. The propagation of such aseismic dislocations produces a stress redistribution along the fault and can play a key role in determining the conditions which give rise to earthquakes. 相似文献
18.
Guang-an Zhu Lin-ming Dou Chang-bin Wang Jing Li Wu Cai Zi-wei Ding 《Arabian Journal of Geosciences》2017,10(24):549
A systematic approach to numerically simulating an island longwall panel operation is proposed: it aims to investigate the evolution of overlying strata, static stress and displacement response and dynamic load arising from roof fracturing and fault slip. The results show that due to a small gob width (70 m) on both sides, the evolution height of overlying strata is limited, i.e. the heights of the cave-in zone and fracture zone are 30.98 and 66.91 m, respectively. The numerical model matches the theoretical analysis and field observations. Dynamic analysis reveals that the envelope of mine tremors confirms the good correlation with the evolution of the fracture zone. As the mining panel is far from the fault, fault slip does not occur; at this time, the dynamic load mainly comes from roof fracturing. When mining activities approach the fault, the calculation of the dynamic response of fault slip is performed over the area where the increase of relative shear displacement during dynamic analysis exceeds 0.05 m and where the shear stress along the fault decreases. It is shown that during the initial stage of the mining process, and in a square mining panel, fault slip is more likely to occur, leading to strong tremors and rock bursts, which become more notable in the later stages of the mining of the island panel. 相似文献
19.
Summary Direct shear tests were conducted on a granite to granite interface for the purpose of tracing the evolution of frictional resistance as the initially smooth and polished surface wears during continuing shearing displacement. At the moment when sliding on the freshly manufactured interface starts (first slip), the friction angle is very low, between 15° and 20°, but then it increases with displacement rapidly without reaching a peak in the first test (maximum displacement less than 25 mm). Upon repeated shearing of the same surface (without re-finishing), this process of displacement-strengthening continues until a total accumulated displacement of about one half of one meter is reached. At this point, the angle of friction would typically be between 42° and 44°.Once the residual surface was established, the effect of time-related parameters, the duration of stationary contact under constant normal and shear load and variable displacement rate, were investigated. The frictional resistance is shown to increase with decreasing displacement rate and to increase with the duration of stationary contact.At a normal load greater than about one half of one MPa, shear displacement on a residual surface proceeds in an unstable, stick-slip manner. The change from stable to unstable sliding, that can be effected by either decreasing the sliding velocity or increasing the normal load, is not instantaneous, but occurs over a finite amount of displacement. 相似文献
20.
We have conducted dynamic rupture propagation experiments to establish the relations between in-source stress drop, fracture energy and the resulting particle velocity during slip of an unconfined 2 m long laboratory fault at normal stresses between 4 and 8 MPa. To produce high fracture energy in the source we use a rough fault that has a large slip weakening distance. An artifact of the high fracture energy is that the nucleation zone is large such that precursory slip reduces fault strength over a large fraction of the total fault length prior to dynamic rupture, making the initial stress non-uniform. Shear stress, particle velocity, fault slip and acceleration were recorded coseismically at multiple locations along strike and at small fault-normal distances. Stress drop increases weakly with normal stress. Average slip rate depends linearly on the fault strength loss and on static stress drop, both with a nonzero intercept. A minimum fracture energy of 1.8 J/m2 and a linear slip weakening distance of 33 μm are inferred from the intercept. The large slip weakening distance also affects the average slip rate which is reduced by in-source energy dissipation from on-fault fracture energy.Because of the low normal stress and small per event slip (∼86 μm), no thermal weakening such as melting or pore fluid pressurization occurs in these experiments. Despite the relatively high fracture energy, and the very low heat production, energy partitioning during these laboratory earthquakes is very similar to typical earthquake source properties. The product of fracture energy and fault area is larger than the radiated energy. Seismic efficiency is low at ∼2%. The ratio of apparent stress to static stress drop is ∼27%, consistent with measured overshoot. The fracture efficiency is ∼33%. The static and dynamic stress drops when extrapolated to crustal stresses are 2–7.3 MPa and in the range of typical earthquake stress drops. As the relatively high fracture energy reduces the slip velocities in these experiments, the extrapolated average particle velocities for crustal stresses are 0.18–0.6 m/s. That these experiments are consistent with typical earthquake source properties suggests, albeit indirectly, that thermal weakening mechanisms such as thermal pressurization and melting which lead to near complete stress drops, dominate earthquake source properties only for exceptional events unless crustal stresses are low. 相似文献