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1.
蒙荣国 《中国地质灾害与防治学报》2020,31(3):83-88
由于近年来各种极端天气频发,桂西典型岩溶区发生的岩溶震群活动引起广泛关注。岩溶震群活动具有频度高、震级低、灾害大等特点,为探讨岩溶震群活动震害防治,文章以"6·28"震群研究为基础,分析发现桂西典型岩溶区岩溶震群活动震害主要表现为次生地质灾害的危害及岩溶地基对地表破坏烈度的放大作用,岩溶震群活动主要表现为气爆地震及塌陷地震,通过分析其作用机理,从减小地震发生概率出发,文章认为桂西典型岩溶区岩溶震群活动震害防治可从认知、辅助治理、工程治理三个层次进行探讨。 相似文献
2.
广从断裂是粤中地区一条重要的北东向基底断裂,对于该断裂在珠江三角洲隐伏段的晚第四纪活动性的认识存在分歧.针对最近在广从断裂东侧佛山市西淋岗发现的断错晚第四纪地层现象,开展了地质地貌调查、探槽揭露、第四系年代测定和浅层人工地震探测等工作.对“西淋岗断层”的几何学特征及与基岩断裂的相关性进行了探测和分析,论证了其成因.“西淋岗断层”是新生的重力滑动面,并不是晚第四纪活动断层,与地震无关.目前尚未发现广从断裂晚第四纪以来活动的地质地貌证据,因此不能说明该断裂具备发生强烈地震的构造能力. 相似文献
3.
江娃利 《地壳构造与地壳应力文集》1996,(Z1)
本文从地表地震断层、全新世断裂活动及区域构造讨论了华北平原近300年6次强震的构造特征.研究结果表明,这6次强震均有相应的地表地震断层出现,并与它们各自极震区等震线长轴方向一致.北西向地表地震断层为左旋走滑,北东向地表地震断层为右旋走滑.这些地区存在全新世活动断裂及古地震现象表明这些强震不是当地的首次强震破裂,华北平原强震存在原地重复现象.区域地震构造分析结果表明,强震地点与华北平原内第三纪断陷盆地的关系并不明显,而全新世活动断裂与华北平原周边构造的交叉部位则是近代强震活跃地区,也是值得注意的未来强震危险地点. 相似文献
4.
全球到处发育的隐爆角砾岩表明隐爆作用的普遍性,并标志着古地震的一种形成机制。隐爆角砾岩具有特殊的角砾形状和构造。地震地质资料表明大地震产生的地表破裂带没有肉眼可观测到的断层位移。材料聚集应变能估算值表明岩石聚集的应变能不足以产生大地震。携带高能量的地核-地幔流体不仅为自己逸散提供了能量,而且为产生地震提供了充足的能量。深部流体以运移-聚集-爆炸-运移-聚集-爆炸的循环方式向地表逃逸,在地球内部不同深度产生了不同震级的地震。因此,超高压流体隐爆应该是地震形成的主要机制。地震隐爆成因机制不仅能够更好地解释各种天然地震(中深源地震、震群、慢地震和非双力偶性地震等)以及全球地震、火山和地热带的空间吻合,而且能够解释隐爆角砾岩及其伴生矿的形成。 相似文献
5.
石胜群 《沉积与特提斯地质》2008,28(3):84-88
北部湾盆地的迈陈凹陷东部地区浅层广泛分布第四纪火成岩,地表条件复杂,发育多期断裂系统,构造破碎,导致地震资料品质较差,构造解释及圈闭描述难度大。笔者在开展解释处理一体化以提高地震资料品质的同时,建立区域构造地质模型,综合运用多种解释技术手段,进行构造解释研究。解决了速度及多期活动小断层的识别及断层组合的解释等问题,提高了圈闭的可信度和构造解释方案的准确性。 相似文献
6.
2010年6月28日至8月中旬,广西凤山县至凌云县一带发生3级震群活动(简称"6·28"震群,亦称凌云—凤山3级震群活动),该震群震源浅、频次高、烈度大、灾害重。"6·28"震群发生于包容式岩溶区,该区降雨集中,地下水暴涨暴落,受地层岩性、地质构造及外源水的控制,岩溶发育强烈,巨大洞穴多处可见,尤其发现多处岩溶反虹管。文章通过对地震时的表象现象调查及深入研究当地岩溶水文地质条件,发现"6·28"震群震区存在岩溶气爆地震及岩溶陷落地震的有利条件,并通过研究期间的监测验证,认为"6·28"震群存在岩溶气爆地震及岩溶陷落地震,属暴雨诱发的岩溶震群活动。 相似文献
7.
四川蒲江地区熊坡断层带（区域上称蒲江-新津断裂带）在第四纪还有强烈活动,是一条活动断层。该断层在新津地区被第四系覆盖,往北东通过成都市主城区。通过野外地质调查发现：该断层无强烈地震所具有的高滑动速率;在构造方面该断层未断入地壳深部的高能干岩层中,断层的岩性强度较低,因此该断层积蓄较大的能量是不容易的,发生较大地震的可能性也不大。 相似文献
8.
四川汶川5.12大地震同震滑动断层泥的发现及意义 总被引：4，自引：0，他引：4
2008年汶川8.0级地震沿龙门山断裂带内的映秀—北川断裂和灌县—安县断裂产生了近300 km的同震地表破裂带。震后地质科学考察发现地表变形以逆冲为主,并伴有右旋走滑。地震地表破裂带大多沿古生代碳质泥岩、页岩和三叠系煤系地层内的滑动面出露地表,这些软弱地层为地震破裂带冲到地表提供了超低摩擦滑动带。我们发现在同震垂直和水平位错达6m左右的地表破裂带,地震的同震滑动发生在厚度约0.5~2cm 的狭窄滑动带内,以发育新鲜的灰色断层泥为特征,这些断层泥是地震断层快速滑动过程中岩石—流体相互作用的结果。 相似文献
9.
近10年以来,在四川盆地南部的川黔滇交界地区发生了一系列中、强地震,其发震机理引起了广泛的关注和讨论。本文基于历史地震震中分布和区域活动断裂构造编图,发现四川盆地南部地震主要集中在4个地震亚区,分别为马边—永善、鲁甸、长宁和自贡—荣昌等地震亚区,华蓥山断裂带西南段是其中一条重要的地震构造边界带。通过综合分析主、余震分布特征、震源深度和震源机制解等资料,认为该地震区存在2类发震断层,其中马边—永善、鲁甸、长宁地震亚区以基底断层走滑型或走滑逆冲型地震为主,而自贡—荣昌亚区则以浅层滑脱断层逆冲型地震为主。区域挤压应力方向从WNW ESE向至ENE WSW向。双震型地震频发,一次走滑地震往往会触发一组共轭基底断层的同时活动。这些地震构造特征表明它们不同于盆地西缘的龙门山—岷山逆冲走滑型地震构造带,也不同于鲜水河—安宁河—小江走滑型地震构造带,属于一个新生的克拉通地震构造区,因西南扬子地块遭受青藏高原的向东推挤和压迫,构造应力通过“大凉山地块”传递并作用到四川盆地南部,导致扬子地块的断块型结构及其基底断层的逆冲走滑活动,进而主导了该地区的一系列中、强地震的破裂事件。 相似文献
10.
南海海槽是全球大地震发生频率最高的地区之一,该地区增生楔上斜坡盆地内的重力流沉积记录了多分支断层及大地震活动历史.利用国际综合大洋钻探计划(IODP)314-316航次岩心-地震-综合测井资料,在详细分析南海海槽增生楔上斜坡盆地内重力流沉积特征基础上,阐明了其对多分支断层和大地震活动的响应机制.研究结果表明,南海海槽增生楔上斜坡盆地内依次充填了楔形块体流、峡谷和表层块体流沉积:楔形块体流形成于多分支断层活动早期,表现出北厚南薄的楔形特征,反映了多分支断层的持续活动的特征,沉积物中富含的粗颗粒泥质角砾岩反映了早期多分支断层剧烈活动的特征;峡谷系统由密集峡谷,大型块体流和轴向峡谷组成,主要受到多分支断层耦合造成斜坡变陡、区域地层孔隙流体压力增大和盆地不均衡抬升的影响;表层块体流位于盆地顶部,由多期次弱振幅块体流叠加组成,现今海底表面表现为大量“马蹄形”的垮塌地形,这些相对短期内广泛分布的块体流应该是由地震引起的地表震动触发的.斜坡盆地内重力流沉积特征反映了多分支断层活动历史以及大地震的发生过程:即1.95~1.55 Ma,多分支断层形成初期活动剧烈,逆冲活动造成了断层上盘沉积物垮塌,楔形块体流沉积在斜坡盆地底部;1.55~1.07 Ma,多分支断层西部耦合,导致斜坡盆地出现东高西低的构造格局以及盆地西部区域楔体和断层处能量的集聚;1.07 Ma至今,断层处能量间断释放,引发多次大地震. 相似文献
11.
1997年1月2日~1998年12月31日新疆伽师地震群的发生,使柯坪断裂的滑动速率和运动方向发生了改变。利用MD系列断层仪对柯坪断裂东段的运动特征进行了观测与研究。结果表明,柯坪断裂带东段在伽师地震群前后,垂直滑动速率由0.037 mm/a提高到0.069 mm/a,水平错动速度由左旋0.033 mm/a改变为右旋0.016 mm/a;水平运动方向发生了改变,垂直运动强度提高了近一倍;伽师震群发生前后,柯坪断裂东段附近的应力场发生了改变,最大和最小水平应变率的大小虽未变化,但主应变率轴绕顺时针方向旋转了16.7°。 相似文献
12.
滇西南2014年景谷中-强震群的地质构造成因——茶房-普文断裂带贯通过程的构造响应 总被引：1，自引：1，他引：0
2014年10—12月期间,云南景谷接连发生了Ms6.6、Ms5.8、Ms5.9三次中-强地震。为确定地震的地质构造成因,在地表调查的基础上,综合该区的地质构造情况、烈度与余震分布、震源机制解等资料,确定此次震群活动的宏观震中位于永平盆地东南侧山地,发震断层为地质与地貌表现不显著的NW向右旋走滑断层。此次震群活动及余震迁移过程指示,由于断层斜接部位岩桥的临时阻碍,Ms6.6地震破裂在向南东扩展过程中发生短暂停滞,突破障碍后进一步引发了Ms5.8和Ms5.9地震,这符合震源破裂沿NW向发震断裂分段破裂的行为。区域活动断裂的遥感解译结果发现,发震断层位置恰好处于NW向右旋走滑的茶房断裂与普文断裂之间,区域上属于该断裂带的不连贯部位,指示此次中-强震群活动应该是茶房-普文断裂带贯通过程的构造活动表现。结合思茅地块的历史地震资料发现,思茅地块地震活动多以小于等于6.8级为主,发震构造多为NW向断裂。指示在现今构造应力场作用下,该区NW向断裂的活动性相对NE向断裂更加显著,属于该区主要控震构造,应在今后的地震地质工作中给予更多关注。 相似文献
13.
Tomomi Okada Akira Hasegawa Jun''ichi Suganomata Norihito Umino Haijiang Zhang Clifford H. Thurber 《Tectonophysics》2007,430(1-4):67-81
A shallow M6.4 inland earthquake occurred on 26 July 2003 in the northern part of Miyagi Prefecture, northeastern Japan. This earthquake was a typical inland thrust earthquake, a type that is common in NE Japan. We obtained a detailed seismic velocity structure in the focal area of this earthquake by the double-difference tomography method. Arrival-time data came from temporary seismic stations deployed above the mainshock fault plane. Both the P-wave and S-wave velocities in the hanging wall were lower than those in the footwall. Aftershocks were aligned along a zone where the seismic velocity changes rapidly. This is consistent with the interpretation that the 2003 northern Miyagi earthquake occurred along a fault that acted as a normal fault in the Miocene and has been reactivated as a reverse fault under the present compressional stress regime. The large slip area by the main shock rupture (asperity) corresponds to an area with relatively high P- and S-wave velocities. A zone with low Vp/Vs was detected along the aftershock area. One of the possible causes of this low-Vp/Vs zone is the existence of high-aspect-ratio pores that contain water. Hypocenters of the main shock, largest foreshock, and largest aftershock are also located within the low-Vp/Vs zone. 相似文献
14.
The Killari earthquake of September 29, 1993 (Mw=6.2) in peninsular India triggered several aftershocks that were recorded by a network of 21 stations. We computed the change in regional static stress caused by coseismic slip on the earthquake rupture and correlated it with the aftershocks with a view to constrain some of the rupture parameters of this earthquake. We evaluated the six available estimates of fault plane solutions for this earthquake and concluded that reverse slip on a 42° dipping, N112° trending fault, which extends up to the surface from a depth of 7 km, produces maximum correlation between the increased static stress and aftershock distribution. Our analysis suggests that the majority of coseismic slip occurred on the part of the rupture that lies in the depth range of 3–6.5 km. 相似文献
15.
In the southern South–North Seismic Zone, China, seismic activity in the Yingjiang area of western Yunnan increased from December 2010, and eventually a destructive earthquake of Ms5.9 occurred near Yingjiang town on 10 March 2011. The focal mechanism and hypocenter location of the mainshock suggest that the Dayingjiang Fault was the site of the mainshock rupture. However, most of foreshocks and all aftershocks recorded by a portable seismic array located close to the mainshock occurred along the N–S-striking Sudian Fault, indicating that this fault had an important influence on these shocks. Coulomb stress calculations show that three strong(magnitude ≥5.0) earthquakes that occurred in the study region in 2008 increased the coulomb stress along the plane parallel to the Dayingjiang Fault. This supports the Dayingjiang Fault, and not the Sudian Fault, as the seismogenic fault of the 2011 Ms5.9 Yingjiang earthquake. The strong earthquakes in 2008 also increased the Coulomb stress at depths of ≤5 km along the entire Sudian Fault, and by doing so increased the shallow seismic activity along the fault. This explains why the foreshocks and aftershocks of the 2011 Yingjiang earthquake were located mostly on the Sudian Fault where it cuts the shallow crust. The earthquakes at the intersection of the Sudian and Dayingjiang faults are distributed mainly along a belt that dips to the southeast at ~40°, suggesting that the Dayingjiang Fault in the mainshock area also dips to the southeast at ~40°. 相似文献
16.
强降雨可诱发新近纪软岩质滑坡滑移变形。1955年至今,降雨在陕西宝鸡诱发超过十起大型滑坡灾害。2011年9月19日,宝鸡市区72 h内的降雨量达到332 mm,北坡金鼎寺、簸箕山与高家崖滑坡出现裂缝,威胁市区居民安全。为分析滑坡的变形机制与降雨触发的滑体内地下水位的波动关系,2012—2015年,开展了降雨量、地下水位、孔隙水压力、滑坡应力与位移等物理量的实时监测,统计分析了它们的频率、活动强度及累积变化规律,提出了滑坡的位移扩展模型。研究显示:(1)地下水的活动会影响新近纪软岩质滑坡的变形,但降雨量、地下水位、孔隙水压力、滑坡体应力与位移等物理量变化机制有差异,地下水位、孔隙水压力呈周期性变化,滑坡体的应力、位移的变化具有累积效应;(2)宝鸡市北坡滑坡运动变形具有蠕变、快速滑移两个阶段。降雨会触发的滑坡体各物理量出现加速变化,地下水位波动幅度为0.27~1m,孔隙水压力的变化幅度为10kPa,滑体浅层的水平应力变化幅度为5.6kPa;(3)在判断降雨能否诱发滑坡快速滑移过程中,既需分析滑体应力、位移变化的累积效应,又需分析新近纪软岩质滑带的摩擦破坏机制。 相似文献
17.
贵州印江朗溪岩溶槽谷龙洞湾泉流量衰减分析 总被引：2，自引：2，他引：0
文章对贵州省印江县朗溪隔槽式向斜岩溶槽谷轴面南东侧的龙洞湾岩溶泉流量衰减规律进行了分析,通过在泉口设置复合堰、安放水文气象自动监测仪,获取了该泉降雨量和相对水位的高时间分辨率监测数据,并采用水力学公式计算了泉流量,分析了降雨过后岩溶泉流量的动态特征,再利用分区间指数函数衰减方程确定了该泉所在含水介质的结构特征及亚储水量,结果发现:（1）龙洞湾泉流量峰值滞后时间受降雨过程特征影响较大,当降雨量大或前期有降雨影响时,滞后时间短;当降雨量小或前期无降雨影响时,滞后时间长;（2）强降雨后,龙洞湾泉流量的衰减可分为三个亚动态,且衰减系数的差异较大,第I亚动态和第II亚动态的衰减系数分别是第III亚动态的11倍和3倍,这表明其三重岩溶含水介质的特征明显;（3）龙洞湾泉的含水介质具有不均匀性,以管道流和裂隙流为主,岩溶发育强烈。 相似文献
18.
Fault movements and stress accumulation before the 1976 Tangshan earthquake in North China 总被引：1，自引：0，他引：1
This paper analyses geodetic data including the results of short baseline and short levelling surveys across active faults, and of relevellings over a wide area collected at Tangshan and in its vicinity during the several years before the 1976 Tangshan earthquake of magnitude 7.8. Using a theoretical model for slip on a fault plane with an arbitrary dip in a viscoelastic half-space, the parameters of the aseismic fault slip prior to the shock are obtained, and the stress changes caused in the area of Tangshan by such slip are estimated. The results are comparable with the seismic activity and the changes in time and space of the b-value in the relation N = exp(a - bM) observed in the same period. It is demonstrated that during 1968–1975 the Cangdong fault, the main NNE-trending active fault in the southwest of the seismic region, had gradually started aseismic right-lateral strike-slip and that the occurrence of the Tangshan earthquake was related to the stress field produced by the slip. Finally, two sequences of periodic earthquake migration that took place in North China during 1966–1976 are discussed in connection with the Tangshan earthquake. 相似文献
19.
Francisco H.R. Bezerra Mrio K. Takeya Maria O.L. Sousa Aderson F. do Nascimento 《Tectonophysics》2007,430(1-4):27-39
Northeastern Brazil is, within the present knowledge of historical and instrumental seismicity, one the most seismic active areas in intraplate South America. Seismic activity in the region has occurred mainly around the Potiguar basin. This seismicity includes earthquake swarms characterized by instrumentally-recorded events ≤ 5.2 mb and paleoseismic events ≥ 7.0. Our study concentrates in the João Câmara (JC) epicentral area, where an earthquake swarm composed of more than 40,000 aftershocks occurred mainly from 1986 to 1990 along the Samambaia fault; 14 of which had mb > 4.0 and two of which had 5.1 and 5.0 mb. We describe and compare this aftershock sequence with the present-day stress field and the tectonic fabric in an attempt to understand fault geometry and local control of seismogenic faulting. Earthquake data indicate that seismicity decreased steadily from 1986 to 1998. We selected 2,746 epicenters, which provided a high-quality and precise dataset. It indicates that the fault trends 37° azimuth, dips 76°–80° to NW, and forms an alignment 27 km long that cuts across the NNE–SSW-trending ductile Precambrian fabric. The depth of these events ranged from 1 km to 9 km. The fault forms an echelon array of three main left-bend segments: one in the northern and two in the southern part of the fault. A low-seismicity zone, which marks a contractional bend, occurs between the northern and southern segments. Focal mechanisms indicate that the area is under an E–W-oriented compression, which led to strike–slip shear along the Samambaia fault with a small normal component. The fault is at 53° to the maximum compression and is severely misoriented for reactivation under the present-day stress field. The seismicity, however, spatially coincides with a brittle fabric composed of quartz veins and silicified-fault zones. We conclude that the Samambaia fault is a discontinuous and reactivated structure marked at the surface by a well-defined brittle fabric, which is associated with silica-rich fluids. 相似文献
20.
LU Renqi HE Dengf JOHN Suppe MA Yongsheng GUAN Shuwei SUN Yanpeng GAO Jinwei 《《地质学报》英文版》2011,85(6):1277-1285
In January 2010, the Suining Ms5.0 earthquake occurred in central Sichuan Basin, with the epicenter in Moxi-Longnvsi structural belt and a focal depth of 10 km. Based on structural interpretations of seismic profiles in this area, we recognized a regional detachment fault located at a depth of 9–10 km in the Presinian basement of the Suining area, transferring its slipping from NW to SE orientation. This detachment fault slipped from NW to SE, and underwent several shears and bends, which caused the basement to be rolled in and the overlaying strata fold deformation. It formed a fault-bend fold in the Moxi area with an approximate slip of 4 km. Correspondingly, the formation of the Moxi anticline is related to the detachment fault. With the earthquake’s epicenter on the ramp of the detachment fault, there is a new point of view that the Suining earthquake was caused by re-activation of this basement detachment fault. Since the Late Jurassic period, under the influence of regional tectonic stress, the detachment fault transfered its slip from the Longmen Mountains (LMS) thrust belt to the hinterland of the Sichuan Basin, and finally to the piedmont zone of southwest Huayingshan (HYS), which indicates that HYS might be the final front area of the LMS thrust belt. 相似文献