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1.
The Bekten Fault is 20-km long N55°E trending and oblique-slip fault in the dextral strike-slip fault zone. The fault is extending sub-parallel between Yenice-Gönen and Sar?köy faults, which forms the southern branch of North Anatolian Fault Zone in Southern Marmara Region. Tectonomorphological structures indicative of the recent fault displacements such as elongated ridges and offset creeks observed along the fault. In this study, we investigated palaeoseismic activities of the Bekten Fault by trenching surveys, which were carried out over a topographic saddle. The trench exposed the fault and the trench stratigraphy revealed repeated earthquake surface rupture events which resulted in displacements of late Pleistocene and Holocene deposits. According to radiocarbon ages obtained from samples taken from the event horizons in the stratigraphy, it was determined that at least three earthquakes resulting in surface rupture generated from the Bekten Fault within last ~1300 years. Based on the palaeoseismological data, the Bekten Fault displays non-characteristic earthquake behaviour and has not produced any earthquake associated with surface rupture for about the last 400 years. Additionally, the data will provide information for the role of small fault segments play except for the major structures in strike-slip fault systems.  相似文献   

2.
2010年青海玉树Ms 7.1级大地震引发了一系列次生地质灾害,其中地震落石是除地震滑坡外沿断裂带及其邻侧最常见的现象。对玉树震区落石的调查发现,该区多处存在非常典型的多期地震落石分布现象,指示该区地震落石的发育与其他古地震现象类似,具有多期性和一定的原地复发性。实地调查表明,该区地震落石分布的主要特征为:多集中发育在活动断裂带附近的陡峭基岩斜坡下方,分布零散,且滚动较远,并常与古地震滑坡相伴生。初步获得的8个地震落石钙膜U系测年结果分布在距今6030±300a BP、4720±210a BP、3530±490~3560±280a BP、2010±160a BP、1090±70a BP、760±20a BP和230±20a BP年龄段,与该区古地震探槽和滑坡反映的地震事件比较吻合,进一步揭示玉树断裂带附近在全新世中晚期发生过多期可导致地表产生地震落石的事件。同时也说明,地震落石及其钙膜测年是特别值得进一步探索的潜在古地震研究方法或途径。  相似文献   

3.
Palaeoseismological and archaeoseismological studies in the Kurai fault zone, along which the Kurai Range is thrust onto Cenozoic deposits of the Chuya intramontane basin, led to the identification of a long reverse fault scarp 8.0 m high. The scarp segments are primary seismic deformations of large ancient earthquakes. The scarp’s morphology, results of trenching investigations, and deformations of Neogene deposits indicate a thrusting of the piedmont plain onto the Kurai Range, which is unique for the Gorny Altai. Similarly for Northern Tien Shan, we explain this by the formation of both a thrust transporting the mountain range onto the depression and a branching thrust dislocation that forms the detected fault scarp. In a trench made in one of the scarp segments, we identified the parameters of the seismogenic fault – a thrust with a 30° dipping plane. The reconstructed displacement along the fault plane is 4.8 m and the vertical displacement is 2.4 m, which indicates a 7.2–7.6 magnitude of the ancient earthquake. The 14C age of the humus-rich loamy sand from the lower part of the colluvial wedge constrains the age of the earthquake at 3403–3059 years BP. Younger than 2500 years seismogenic displacements along the fault scarp are indicated by deformations of cairn structures of the Turalu–Dzhyurt-III burial mound, which was previously dated as iron age between the second half of I BC and I AD.  相似文献   

4.
Coseismic soft-sediment deformation has been studied by structural and tectononophysical methods in the Selenga Delta area shaken by the devastating M ～ 7.5 Tsagan earthquake in 1862. Among the documented deformation structures (seismites), clastic dikes are the most reliable paleoseismic indicators. The dikes have their sizes and extent showing proximity to the primary coseismic rupture zone and are closely associated with faults of different hierarchic levels. The Tsagan event occurred under SW–NE extension as motion on a stepped system of normal faults dipping at 300°–350°, ∠45°–75°.The amount of vertical motion measured against a reference layer in a trench reached 2.83 m, and the maximum dip displacement measured in a single fracture was 0.5 m. The earthquake was generated by the Delta Fault that dips at 60° on average to the northwest.The distribution of quantitative parameters of brittle and brittle-plastic deformation has been analyzed along two profiles, and two new parameters were introduced: indices of mean intensity (I) of clastic dikes and microdikes; the new parameters were calculated by specially developed equations. Summation of significant peaks in all parameters (SUMspp) allowed contouring the zone of most intense soft-sediment deformation near Dubinino Village.Deformation mostly propagated in the NE–SW and N–S directions. The location of the 1862 Tsagan earthquake at 52.35° N and 106.67° E was inferred from the SUMspp value taking into account the dip of the causative fault plane and the average origin depth of earthquakes in the Baikal rift. The approach we used is applicable to locating preinstrumental events.The recurrence of large earthquakes in the area of Proval Bay (Lake Baikal) has been estimated to be 1120–1230 years proceeding from alternating deformed and undeformed sediments in the sections, their thicknesses and deposition rates according to radiocarbon dating. The seismic activity has been associated with the same fault which can generate M ≥ 7 events.  相似文献   

5.
Luigi Piccardi   《Tectonophysics》2005,408(1-4):113
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6.
The >200 km long Moonlight Fault Zone (MFZ) in southern New Zealand was an Oligocene basin-bounding normal fault zone that reactivated in the Miocene as a high-angle reverse fault (present dip angle 65°–75°). Regional exhumation in the last c. 5 Ma has resulted in deep exposures of the MFZ that present an opportunity to study the structure and deformation processes that were active in a basin-scale reverse fault at basement depths. Syn-rift sediments are preserved only as thin fault-bound slivers. The hanging wall and footwall of the MFZ are mainly greenschist facies quartzofeldspathic schists that have a steeply-dipping (55°–75°) foliation subparallel to the main fault trace. In more fissile lithologies (e.g. greyschists), hanging-wall deformation occurred by the development of foliation-parallel breccia layers up to a few centimetres thick. Greyschists in the footwall deformed mainly by folding and formation of tabular, foliation-parallel breccias up to 1 m wide. Where the hanging-wall contains more competent lithologies (e.g. greenschist facies metabasite) it is laced with networks of pseudotachylyte that formed parallel to the host rock foliation in a damage zone extending up to 500 m from the main fault trace. The fault core contains an up to 20 m thick sequence of breccias, cataclasites and foliated cataclasites preserving evidence for the progressive development of interconnected networks of (partly authigenic) chlorite and muscovite. Deformation in the fault core occurred by cataclasis of quartz and albite, frictional sliding of chlorite and muscovite grains, and dissolution-precipitation. Combined with published friction and permeability data, our observations suggest that: 1) host rock lithology and anisotropy were the primary controls on the structure of the MFZ at basement depths and 2) high-angle reverse slip was facilitated by the low frictional strength of fault core materials. Restriction of pseudotachylyte networks to the hanging-wall of the MFZ further suggests that the wide, phyllosilicate-rich fault core acted as an efficient hydrological barrier, resulting in a relatively hydrous footwall and fault core but a relatively dry hanging-wall.  相似文献   

7.
河套断陷带大青山山前断裂晚第四纪古地震完整性研究   总被引：11，自引：0，他引：11  
冉勇康  张培震  陈立春 《地学前缘》2003,10(Z1):207-216
通过沿大青山山前断裂 18个探槽的古地震分析 ,分别确定了 5个段落的 2 2次古地震事件。呼和浩特段 ,距今约 1.9万a以来 7次 ,平均重复间隔时间 (2 4 6 2± 4 13)a ;毕克齐段距今 2 .2万a以来 4次 ;土左旗西段距今 1.1万a以来 4次 ,平均重复间隔时间 (2 94 8± 5 6 0 )a ;土右旗西段距今约 1.1万a以来 5次 ,平均重复间隔时间 (2 2 89± 36 0 )a ;包头段距今 2 .3万a以来 2次。由断层位移量限定法和多探槽校验法判定 ,大青山山前断裂已揭露的古地震事件还不完全代表晚第四纪全断裂的大地震活动历史。只有在呼和浩特段 1.9万a以来、土左旗西段和土右旗西段约 1.1万a以来活动历史基本完整。其它两个段落不完整。这是用这些古地震资料评价该断裂未来地震危险性 ,以及今后进一步工作时应注意的问题。  相似文献   

8.
This study's objective was to investigate the Guguan-Xiangong Fault, which lies in the southern Liupanshan area, through satellite image interpretation and field observations. Guguan-Xiangong Fault is divided into five subsegments; among these, the Badu-Longwei segment has been the most recently active. The geomorphic features of the Badu-Longwei segment are clearly displayed, including multiple high fault scarps with fresh bedrock free faces. There is significant evidence for Holocene activity of the three fault sections, located in Renhuashu, Tianjiagou, and Xinjiecun respectively. The three sections feature distinct episodic deposition and fault scratches. Based on 14 Cdating and field observations on the three fault sections, two or more paleoearthquakes across the Badu-Longwei fault segment are ascertained, between 5874±116 and 5430±140 a BP, and after 2037±83 a BP respectively. The Badu-Longwei segment of the Guguan-Xiangong Fault is preliminarily extrapolated as the seismogenic structure of the 600 A.D. Qin-Long earthquake.  相似文献   

9.
Geometric and kinematic analyses of minor thrusts and folds, which record earthquakes between 1200 AD and 1700 AD, were performed for two trench sites (Rampur Ghanda and Ramnagar) located across the Himalayan Frontal Thrust (HFT) in the western Indian Himalaya. The present study aims to re-evaluate the slip estimate of these two trench sites by establishing a link between scarp geometry, displacements observed very close to the surface and slip at deeper levels. As geometry of the active thrust beneath the scarp is unknown, we develop a parametric study to understand the origin of the scarp surface and to estimate the influence of ramp dip. The shortening estimates of Rampur Ghanda trench by line length budget and distance–displacement (D–d) method show values of 23 and 10–15 %, respectively. The estimate inferred from the later method is less than the line length budget suggesting a small internal deformation. Ramnagar trench shows 12 % shortening by line length budget and 10–25 % by the D–d method suggesting a large internal deformation. A parametric study at the trenched fault zone of Rampur Ghanda shows a slip of 16 m beneath the trailing edge of the scarp, and it is sufficient to raise a 8-m-high scarp. This implies that the Rampur Ghanda scarp is balanced with a single event with 7.8-m-coseismic slip in the trenched fault zone at the toe of the scarp, 8–15 % mean deformation within the scarp and 16-m slip at depth along a 30° ramp for a pre-1400 earthquake event. A 16-m slip is the most robust estimate of the maximum slip for a single event reported previously by trench studies along the HFT in the western Indian Himalaya that occurred between 1200 AD and 1700 AD. However, the Ramnagar trenched fault zone shows a slip of 23 m, which is larger than both line length and D–d methods. It implies that a 13-m-high scarp and 23-m slip beneath the rigid block may be ascribed to multiple events. It is for the first time we report that in the south-eastern extent of the western Indian Himalaya, Ramnagar scarp consists of minimum two events (i) pre-1400 AD and (ii) unknown old events of different lateral extents with overlapping ruptures. If the more optimistic two seismic events scenario is followed, the rupture length would be at least 260 km and would lead to an earthquake greater than Mw 8.5.  相似文献   

10.
The Xiaojiang fault is a major active left-lateral fault along the southeastern margin of the Tibetan Plateau.The largest historical earthquake in Yunnan Province, with a magnitude 8 and a mean coseismic left-lateral displacement of ~ 6.9 m, occurred on the western branch of the Xiaojiang fault.Studying this fault is important in understanding current deformation and kinematic characteristics of the Tibetan Plateau.Activities and stretches have been well undertaken on the Xiaojiang fault, while paleoseismic research work is always the weak link on this fault.To investigate the paleoseismic history and large earthquake activity of the Xiaojiang fault, we opened a large trench at the northern edge of Caohaizi sag pond on the western branch of the Xiaojiang fault.Six paleoseismic events have been identified, and named E1 through E6 from the oldest to the youngest.Charcoal and woods are abundant, 20 samples were dated to constrain the ages of the paleoseismic events at 40 000–36 300 BC, 35 400–24 800 BC, 9 500 BC–AD 500, AD 390–720, AD 1120–1620 and AD 1750–present.We associate the youngest event E6 with the 1833 M8 earthquake.Events E4, E5 and E6 show a continuous record of the western strand of the Xiaojiang fault in the late Holocene, with a average recurrence interval of 370–480 yr.Large earthquake recurrence in the late Holocene is far less than the recurrence of 2000–4000 yr posed in previous studies.Thus, the seismic hazard on the Xiaojiang fault should be reevaluated.Furthermore, the irregular recurrence of large earthquakes on the Xiaojiang fault and other faults in the Xianshuihe-Xiaojiang system, indicates the uneven southeastward extrusion of the Sichuan-Yunnan block along the southeastern margin of the Tibetan Plateau.  相似文献   

11.
东昆仑断裂带西大滩段全新世古地震研究*   总被引：2，自引：5，他引：2  
对东昆仑断裂带西大滩段进行了断错地貌填图和古地震探槽揭露,共揭露出6次古地震事件,它们的年龄分别为10302±651aB.P. , 8650±500aB.P. , 7160±506aB.P. , 2830±170aB.P. , 1985±121aB.P.和1540±92aB.P. ;古地震重复间隔分别为1652±820a,1490±711a,4330±534a,845±209a和445±152a。研究发现,西大滩段全新世古地震活动具有丛集现象和重复间隔时间的分段性,第1丛集期在10300~7100aB.P.期间,平均重复间隔1571±543a,第2丛集期在2800~1500aB.P.期间,重复间隔400~800a左右,平均重复间隔645±129a,两个丛集期间隔4300a。西大滩段全新世地震活动规律对昆仑山地区未来地震危险性评估具有重要意义。  相似文献   

12.
The East Anatolian Fault Zone (EAFZ) is among the most important active continental transform fault zones in the world as testified by major historical and minor instrumental seismicity. The first paleoseismological exploratory trenching study on the EAFZ was done on the Palu–Lake Hazar segment (PLHS), which is one of the six segments forming the fault zone, in order to determine its past activity and to assess its earthquake hazard.The results of trenching indicate that the latest surface rupturing earthquakes on this segment may be the Ms=7.1+ 1874 and Ms=6.7 1875 events, and there were other destructive earthquakes prior to these events. The recurrence interval for a surface rupturing large (M>7) earthquake is estimated as minimum 100±35 and maximum 360 years. Estimates for the maximum possible paleoearthquake magnitude are (Mw) 7.1–7.7 for the Palu–Lake Hazar segment based on empirical magnitude fault rupture relations.An alluvial fan dated 14,475–15,255 cal years BP as well as another similar age fan with an abandoned stream channel on it are offset in a left-lateral sense 175 and 160.5 m, respectively, indicating an average slip rate of 11 mm/year. Because 127 years have elapsed since the last surface rupturing event, this slip rate suggests that 1.4 m of left-lateral strain has accumulated along the segment, ignoring possible creep effects, folding and other inelastic deformation. A 2.5 Ma age for the start of left-lateral movement on the segment, and in turn the EAFZ, is consistent with a slip rate of 11 mm/year and a previously reported 27 km total left-lateral offset. The cumulative 5–6 mm/year vertical slip rate near Lake Hazar suggests a possible age of 148–178 ka for the lake. Our trenching results indicate also that a significant fraction of the slip across the EAFZ zone is likely to be accommodated seismically. The present seismic quiescence compared with the past activity (paleoseismic and historic) indicate that the EAFZ may be “locked” and accumulating elastic strain energy but could move in the near future.  相似文献   

13.
At 08:02 on April 20, 2013, a Ms7.0 earthquake occurred in Lushan, Ya'an, in the Longmenshan fault zone, Sichuan. The epicenter was located between Taiping Town and Shuangshi Town, Lushan County and the maximum earthquake intensity at the epicenter reached class IX. Field investigations in the epicenter area found that, although buildings were seriously damaged, no obvious surface rupture structure was produced, only some ground fissures and sand blows and water ejection phenomena being seen. An integrated analysis of high-resolution remote sensing image interpretation, mainshock and aftershock distribution, and focal mechanism solutions indicated that this earthquake was an independent rupturing event in the southwestern segment of the Longmenshan fault zone, belonging to the thrust-type earthquake. Ruptures occurred along the south-central segment of the Shuangshi-Dachuan fault and the principal rupture plane dipped SW at 33-43°. It is inferred that the Lushan earthquake might be related to the ramp activity of the basal detachment zone (13-19 km) of the Longmenshan fault zone. Historically, there occurred at least two Ms6-6.5 earthquakes along the Shuangshi-Dachuan fault zone; thus it is thought that the Lushan earthquake, different from the Wenchuan earthquake, was a characteristic one in the southwestern segment of the Longmenshan fault zone. In-situ stress measurements indicated the Lushan earthquake was the result of stress release of the southwestern segment of the Longmenshan fault zone after the Wenchuan earthquake. This paper analyzes the tectonic setting of the seismogenic structure of this earthquake.  相似文献   

14.
芦山地震发震构造及其与汶川地震关系讨论   总被引：14，自引：0，他引：14  
芦山地震发生在巴彦喀拉块体与华南块体之间龙门山推覆构造带南段。野外考察表明,芦山地震在震中区没有形成具有构造地质意义的地震地表破裂带,仅在各山前陡坡地带出现平行于山麓陡坡的张性地裂缝、山地基岩崩塌、滑坡等边坡震动失稳现象和震动引起的砂土液化现象。重新定位的芦山地震余震分布、震源机制解和地表构造地质等分析表明,芦山地震的发震断层为一条现今尚未出露地表、其上断点仍埋藏在地下9 km以下地壳中的一条盲逆断层,走向212°,倾向NW,倾角38°±2°,上断点以上至地表的构造变形符合断层扩展背斜模型。根据汶川地震和芦山地震的余震空间分布、地震破裂过程、深浅构造关系等差异反映出它们是分别发生在龙门山推覆构造带中段和南段的两次独立地震破裂事件。  相似文献   

15.
The 2004 Mid-Niigata Prefecture earthquake sequence (mainshock magnitude, MJMA 6.8), which occurred in an active fold-and-thrust belt in northern central Japan, generated a small thrust surface rupture (< 20 cm of vertical displacement) along a previously unmapped northern extension of the active Muikamachi–Bonchi–Seien fault zone, on the eastern margin of the epicentral region. To better understand past seismic behavior of the rupture, we conducted a paleoseismic trenching study across the 10-cm-high west-side-up surface rupture at the foot of a pre-existing 1.8-m-high east-facing scarp, which probably resulted from past earthquake(s). A well-defined west-dipping thrust fault zone accompanied by drag folding and displacing the upper Pliocene to lower Pleistocene strata and the unconformably overlying upper Pleistocene (?) to Holocene strata was exposed. The principal fault zone is connected directly to the 2004 surface rupture. From the deformational characteristics of the strata and radiocarbon dating, we inferred that two large paleoseismic events occurred during the past 9000 years prior to the 2004 event. These two pre-2004 events have a nearly identical fault slip (at minimum, 1.5 m), which is ≥ 15 times that of the 2004 event (∼ 10 cm). These paleoseismic data, coupled with the geological and geomorphological features, suggest that the 2004 event represented non-characteristic behavior of the fault, which can potentially generate a more destructive earthquake accompanied by meter-scale surface displacement. This study provides insight into the interpretation of past faulting events and increases our understanding of rupture behavior.  相似文献   

16.
The 1515 M7? Yongsheng earthquake is the strongest earthquake historically in northwest Yunnan. However, its time, magnitude and the seismogenic fault have long been a topic of dispute. In order to accurately define those problems, a 1:50000 active tectonic mapping was carried out along the northern segment of the Chenghai–Binchuan fault zone. The result shows that there is an at least 25 km–long surface rupture and a series of seismic landslides distributed along the Jinguan fault and the Chenghai fault. Radiocarbon dating of the ~(14) C samples indicates that the surface rupture should be a part of the deformation zone caused by the Yongsheng earthquake in the year 1515. The distribution characteristics of this surface rupture indicate that the macroscopic epicenter of the 1515 Yongsheng earthquake may be located near Hongshiya, and the seismogenic fault of this earthquake is the Jinguan–Chenghai fault, the northern part of the Chenghai–Binchuan fault zone. Striations on the surface rupture show that the latest motion of the fault is normal faulting. The maximum co–seismic vertical displacement can be 3.8 m, according to the empirical formula for the fault displacement and moment magnitude relationship, the moment magnitude of the Yongsheng earthquake was Mw 7.3–7.4. Furthermore, combining published age data with the ~(14) C data in this paper reveals that at least four large earthquakes of similar size to the 1515 Yongsheng earthquake, have taken place across the northern segment of the Chenghai–Binchuan fault zone since 17190±50 yr. BP. The in–situ recurrence interval of Mw 7.3–7.4 characteristic earthquakes in Yongsheng along this fault zone is possibly on the order of 6 ka.  相似文献   

17.
汶川M_s 8.0级地震地表破裂带近断层水平缩短量研究   总被引：1，自引：0，他引：1  
2008年5月12日四川汶川发生Ms8.0特大地震后,地表同震位移量已有了大量的详细调查和研究,然而对于近断层同震水平缩短量的研究却相对较少。笔者在中央断裂、前山断裂以及北西向分支断裂上选择合适地点进行大量探槽开挖,获得了近断层同震水平缩短量的分布情况为:中央断裂清平镇(2.8 m)、擂鼓镇(3.2 m)、平通镇(1.3 m),前山断裂白鹿镇(2.5 m)、九龙镇(1.4 m)、汉旺镇(0.6 m)。文中进一步在中央断裂和小鱼洞分支断裂地表破裂带上开挖数个探槽研究其近断层水平缩短量的问题,得到结果如下:龙门山中央断裂带映秀镇、擂鼓镇、平通镇探槽近断层水平缩短量分别约为(2.6±0.1)m、(2.6±0.2)m、(1.8±0.1)m;小鱼洞分支断层近断层水平缩短量约为(2±0.1)m。汶川5.12地震中央断裂地表破裂近断层较大水平缩短量出现在深溪沟和擂鼓一带,分别约为3.4 m、3.2 m;前山断裂地表破裂带近断层水平缩短量最大值出现在白鹿一带,约为2.5 m,白鹿以北,近断层水平缩短量逐渐减小。中央断裂和前山断裂联合破裂段水平缩短量值之和大于中央断裂带其两侧段落,最大水平缩短量总和可能约为5.3 m,地表破裂带近断层水平缩短量为整个地壳缩短量的主体部分。  相似文献   

18.
鲜水河断裂带色拉哈段是2014年康定MS6.3地震的发震断裂段, 其最新一次地表破裂事件(1725年康定7级地震)的离逝时间较长, 是最可能发生7级以上地表破裂型大震的危险地段之一。获得色拉哈段最新地震地表破裂的展布范围对确定断裂带的地震活动历史、评估断裂带的未来地震危险性以及防震减灾具有重要意义。然而, 迄今色拉哈段最新地表破裂的北西端位置仍存有较大争议。对此, 在以往资料认为没有同震地表破裂的中谷村一带开挖了探槽组, 获得了这一带的破裂历史, 其最新一次事件(E6)的限定年代为A.D.746±51之后。综合探槽剖面证据和附近的断错地貌特征以及历史地震资料, 探槽揭露的最新事件E6可能对应1725年康定7级地震, 色拉哈段的地表破裂北西端至少已延伸到中谷村一带。   相似文献   

19.
The East Anatolian Fault Zone is a continental transform fault accommodating westward motion of the Anatolian fault. This study aims to investigate the source properties of two moderately large and damaging earthquakes which occurred along the transform fault in the last two decades using the teleseismic broadband P and SH body waveforms. The first earthquake, the 27 June 1998 Adana earthquake, occurred beneath the Adana basin, located close to the eastern extreme of Turkey’s Mediterranean coast. The faulting associated with the 1998 Adana earthquake is unilateral to the NE and confined to depths below 15 km with a length of 30 km along the strike (53°) and a dipping of 81° SE. The fixed-rake models fit the data less well than the variable-rake model. The main slip area centered at depth of about 27 km and to the NE of the hypocenter, covering a circular area of 10 km in diameter with a peak slip of about 60 cm. The slip model yields a seismic moment of 3.5?×?1018 N-m (Mw???6.4). The second earthquake, the 1 May 2003 Bingöl earthquake, occurred along a dextral conjugate fault of the East Anatolian Fault Zone. The preferred slip model with a seismic moment of 4.1?×?1018 N-m (Mw???6.4) suggests that the rupture was unilateral toward SE and was controlled by a failure of large asperity roughly circular in shape and centered at a depth of 5 km with peak displacement of about 55 cm. Our results suggest that the 1998 Adana earthquake did not occur on the mapped Göksun Yakap?nar Fault Zone but rather on a SE dipping unmapped fault that may be a split fault of it and buried under the thick (about 6 km) deposits of the Adana basin. For the 2003 Bingöl earthquake, the final slip model requires a rupture plane having 15° different strike than the most possible mapped fault.  相似文献   

20.
On April 20 th, 2013, an earthquake of magnitude MW 6.6 occurred at Lushan of Sichuan on the southern segment of the Longmenshan fault zone, with no typical coseismic surface rupture. This work plotted an isoseismal map of the earthquake after repositioning over 400 post–earthquake macro–damage survey points from peak ground acceleration(PGA) data recorded by the Sichuan Digital Strong Earthquake Network. This map indicates that the Lushan earthquake has a damage intensity of IX on the Liedu scale, and that the meizoseismal area displays an oblate ellipsoid shape, with its longitudinal axis in the NE direction. No obvious directivity was detected. Furthermore, the repositioning results of 3323 early aftershocks, seismic reflection profiles and focal mechanism solutions suggests that the major seismogenic structure of the earthquake was the Dayi Fault, which partly defines the eastern Mengshan Mountain. This earthquake resulted from the thrusting of the Dayi Fault, and caused shortening of the southern segment of the Longmenshan in the NW–SE direction. Coseismal rupture was also produced in the deep of the Xinkaidian Fault. Based on the above seismogenic model and the presentation of coseismic surface deformation, it is speculated that there is a risk of more major earthquakes occurring in this region.  相似文献   

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