The Zoige fifteenth-century 7.2 earthquake ruptures on the Eastern Kunlun Fault,China

Journal of Seismology - The Kunlun Fault System (KFS), situated on the northern border of the Bayan Har block, central-eastern Tibetan Plateau, is among the most important active regional transform...     

龙门山断裂带映秀-北川断裂的古地震及其复发间隔初步研究(英文)

The activity of the Longmenshan thrust belt has concentrated mainly on its Wenchuan-Maoxian Fault, Yingxiu-Beichuan Fault, and Guanxian-Jiangyou fault since the Quaternary time.     

Ground motion simulations for the 23 October 2011 Van,Eastern Turkey earthquake using stochastic finite fault approach

The 23 October 2011 Van (Mw 7.1) earthquake that occurred in Eastern Turkey resulted in heavy damage particularly in the city of Van and town of Ercis. This paper presents ground motion simulations of Van earthquake by using stochastic finite fault method (EXSIM, Motazedian and Atkinson in Bull Seismol Soc Am 95:995–1010, 2005; Boore in Bull Seismol Soc Am 99:3202–3216, 2009) that provides a simple and effective tool to generate high frequency strong motion. The input parameters related to source, path, and site effects are calibrated on the basis of minimizing the error functions between simulations and observations both in time and frequency domain. Validated model parameters are used to produce synthetics in regional extent with the aim of understanding the level and distribution of the ground shaking particularly in the near fault region where no recordings are available within the 40 km of the epicenter. This paper evaluates the effect of two different slip models on ground motion intensity measures over the area of interest and addresses the variability in the near fault region associated with the source effect. The synthetics are compared with the corresponding estimations of ground motion prediction equations by Boore and Atkinson (Earthq Spectra 24:99–138, 2008), Akkar and Bommer (Seismol Res Lett 81:195–206, 2010) and Akkar and Cagnan (Bull Seismol Soc Am 100:2978–2995, 2010). Our results indicate that despite the limitation of the method for incorporating the directivity effect and inadequate representation of the soil conditions at the individual stations, a satisfactory match between synthetics and observations are obtained both in time and frequency domain. Spatial distributions of the synthetics in regional level also show reasonable correlation with ground motion prediction equations and damage observations.     

Archaeological evidence for a destructive earthquake in Patras,Greece

Oriented collapse of columns, large-scale destruction debris and temporary abandonment of the area deduced from an archaeological excavation provide evidence for a major (intensity IX) earthquake in Patras, Greece. This, and possibly a cluster of other earthquakes, can be derived from archaeological data. These earthquakes are not included in the historical seismicity catalogues, but can be used to put constraints to the seismic risk of this city. Patras was affected by a cluster of poorly documented earthquakes between 1714 and 1806. The city seems to be exposed to risks of progressive reactivation of a major strike-slip fault. A magnitude 6.4 earthquake in 2008 has been related to it. This fault has also been associated with a total of four events in the last 20 years, a situation reminiscent of the seismic hazard at the western edge of the North Anatolian Fault.     

Characteristics of fault rocks and paleo-earthquake source along the Koktokay-Ertai fault zone,Xinjiang,China

ＣｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆｆａｕｌｔｒｏｃｋｓａｎｄｐａｌｅｏｅａｒｔｈｑｕａｋｅｓｏｕｒｃｅａｌｏｎｇｔｈｅＫｏｋｔｏｋａｙＥｒｔａｉｆａｕｌｔｚｏｎｅ，Ｘｉｎｊｉａｎｇ，ＣｈｉｎａＬＡＮＢＩＮＳＨＩ１）（史兰斌）ＣＨＵＡＮＹＯＮ...     

Integrated geophysical evidence for a new style of continent-continent collision beneath the western Kunlun in the northwestern China

Along the western Kunlun-Tarim-Tianshan geoscience transect in the northwestern China,an integrated geophysical investigation was carried out. Owing to the abominable natural conditions there,the sounding profile could not cross the whole transect,consequentially,a variety of velocity structures in the transverse and vertical orientations beneath the whole transect were not obtained,such as the case within the western Kunlun orogenic belt. To supply a gap of deep seismic soundings within the western Kunlun ...     

东昆仑断裂带东端的构造转换与2017年九寨沟MS7.0地震孕震机制

2017年四川九寨沟M_S7.0地震是继2008年汶川M_S8.0地震和2013年芦山M_S7.0地震之后,青藏高原东缘在不到十年的时间内发生的第三个震级M_S7.0以上的强震.这次地震发生在东昆仑断裂带东端,作为青藏高原东北缘的一条大型左旋走滑断裂带,东昆仑断裂带与东端其它构造之间的转换关系仍不清楚,因区内地质构造和地形复杂,东昆仑断裂带东端的主要构造仍缺少深入的研究.本文在总结区域地震构造活动特征、历史地震和现代地震基础上,通过东昆仑断裂带东端已有的和最近开展的活动构造定量研究结果,并结合现今GPS变形场资料和2017年九寨沟M_S7.0地震灾害特征分析,发现东昆仑断裂带最东段塔藏断裂上的左旋走滑除了一小部分继续向东传播转移到文县断裂带上外,大部分转化为其南侧的龙日坝断裂带北段、岷江断裂和虎牙断裂上的近东西向地壳缩短,这可能是岷山隆起的构造机制,而2017年九寨沟M_S7.0地震正是左旋走滑的东昆仑断裂带在东端继续向东扩展的结果.

     

The earthquake of Carnuntum in the fourth century a.d. – archaeological results, seismologic scenario and seismotectonic implications for the Vienna Basin fault, Austria

Excavations in the former Roman provincial capital of Pannonia Superior, Carnuntum, 40 km east of Vienna revealed damaged masonry structures from many parts of the ancient settlements. A compilation of structurally damaged buildings has formerly been given by Kandler (Acta Archaeol Acad Sci Hung, 41:313–336, 1989), who related damage to an earthquake in the middle of the fourth century a.d. This paper reviews and supplements these data, and discusses the significance of the style of damage. It is concluded that seismic damage is the only likely interpretation for the damaging mechanism. Although archaeological age dating for the individual collapsed buildings only constrains the timing of their destruction to a few decades around 350 a.d., we assume a single damaging event. In spite of the restrictions on damage assessment by the nature of the archaeological data, it is possible to give a reasonable appraisal of macroseismic intensity. The tentative seismological interpretation of damage leads to an intensity estimate of about nine of the European macroseismic scale (EMS-1998). Comparison with macroseismic data of modern earthquakes in the region, which show a rapid decrease of intensity with distance form the epicentre, indicate a near-by seismic source unless exceptionally high epicentral intensities are assumed for the fourth century event. The most likely source is an active sinistral strike-slip fault (Lassee Fault) passing about 8 km NW of the archaeological site. The fault belongs to Vienna Basin fault system with about 2 mm sinistral movement per year. The system is characterized by fault segmentation and distinct seismicity along the different segments. Moderate seismicity during the last centuries at the southern segments (e.g., Schwadorf 1927, I ₀=8) strongly contrasts from the Lassee fault segment with Carnuntum as the only known severe earthquake. The earthquake of Carnuntum provides evidence for the overall seismic style of deformation along this segment, which previously has not been regarded seismically active. Also, the fourth century earthquake is the strongest event known from the Vienna Basin fault so far.     

1994年台湾海峡7.3级地震发震断层的地震学证据

通过地震学观测资料的分析和研究,并综合其他作者的研究成果,论证了台湾海峡１９９４年７．３级地震发震断层的主破裂面走向应为北西向,地震的发生是由分布于该区域的巴士系构造活动所致。     

昆仑山口西Ms8.1级地震前兆

2001年11月14日,在中国青海、新疆交界地区（35.93°N, 90.54°E）发生了Ms 8.1级地震.在此地震前,距震中超过2000公里的北京工业大学地震研究所 （39.88°N, 116.47°E）收到三种非常清晰的临震信息：次声波异常信号、地应力突变信号及虎皮鹦鹉跳动频率异常信号.     

昆仑山口西地震后中国大陆未来地震形势研究

基于动力学背景和强震活动格局，从多个角度研究了中国大陆及其各次级块体的强震活动趋势。结果表明：2001年11月14日昆仑山口西8．1级地震并不是第五个强震轮回的结束地震，中国大陆特别是青藏块体今后1～3年还将继续发生7级以上地震以进行应力场调整。青藏川交界—四川中部地区是未来最有可能发生7级大震的危险区。     

On a simple method for determining the potential strain energy stored in the earth before a large earthquake

This paper describes a technique for determining the potential energy of deformed material around a future earthquake rupture, with this energy being stored during the precursory period. The basic parameters are the following: rupture length on the Earth’s surface after the earthquake has occurred L, rupture depth h, and the relative block movement along the rupture strike line [`(u)]\bar u. We compared the results for 44 large earthquakes with those derived by determining seismic wave energy from earthquake magnitude.     

Average slip-rate and recent large earthquake ruptures along the Garzê-Yushu fault

Our field investigation obtains new evidence of the later Quaternary activity and recent large earthquake ruptures of the Garzê-Yushu fault. The average left-lateral slip-rate along the fault is determined to be (12 ± 2) mm/a for the last 50000 years from both offset landforms and ages of the correlative sediments. This result is very close to the estimated average left-lateral slip-rate for the Xianshuihe fault, suggesting that the horizontal movement along the northern boundary of the Sichuan-Yunnan active tectonic block and the northeastern boundary of the Qiangtang active tectonic block has been basically harmonious during the later Quaternary period. Remains of ground ruptures of recent large earthquakes have been discovered along all 3 segments of the fault, of which, the 1896 rupture on the northwestern segment is at least 70 km long, and its corresponding earthquake could be of moment magnitude 7.3. The latest rupture on the middle segment of the fault has a length of about 180 km, and was produced by an unknown-age large earthquake that could have a moment magnitude of about 7.7. Along the southeastern segment of the fault, the latest unknown-age rupture is about 65 km long and has a maximum left-lateral coseismic displacement of 5.3 m, and its corresponding earthquake is estimated to be as large as about 7.3 of moment magnitude. Based on relevant investigation, an inference has been drawn that the later two large earthquakes probably occurred in 1854 and 1866, respectively. These demonstrate that the individual segments of the studied Garzê-Yushu fault are all able to produce large earthquakes.     

我国地震断层土壤气流动观测调查

地球是一个巨大的开放系统,地壳放气现象是地壳不同层次进行物质、能量、信息交换的重要形式。因此,强烈放气通道实际上是一个洞察地球内部物理变化、化学变化、应力应变的"窗口"。通过系统观测和记录释放地点、释放量与释放方式,可以了解地壳内压力的变化与通道的开启状况,从而给地震预报、构造活动监测提供重要信息。断层土壤气测量在地震科学领域中应用广泛,且发挥了一定作用。本文在前人研究基础上归纳断层土壤气流动观测研究现状,并对其技术思路、数据分析等展开调查,为深入开展断层土壤气与气体运移关系的研究提出设想,以期形成相对成熟的观测技术系统,为开展地震相关研究服务。笔者认为,地震断层土壤气观测方法尚处于研究初期,不够成熟,但因其具有轻便、快捷、价廉的优点,具有广阔的应用前景与巨大的科学潜力。     

Average slip-rate and recent large earthquake ruptures along the Garzê-Yushu fault

Our field investigation obtains new evidence of the later Quaternary activity and recent large earthquake ruptures of the Garzê-Yushu fault. The average left-lateral slip-rate along the fault is determined to be (12±2) mm/a for the last 50000 years from both offset landforms and ages of the correlative sediments. This result is very close to the estimated average left-lateral slip-rate for the Xianshuihe fault, suggesting that the horizontal movement along the northern boundary of the Sichuan-Yunnan active tectonic block and the northeastern boundary of the Qiangtang active tectonic block has been basically harmonious during the later Quaternary period. Remains of ground ruptures of recent large earthquakes have been discovered along all 3 segments of the fault, of which, the 1896 rupture on the northwestern segment is at least 70 km long, and its corresponding earthquake could be of moment magnitude 7.3. The latest rupture on the middle segment of the fault has a length of about 180 km, and was produced by an unknown-age large earthquake that could have a moment magnitude of about 7.7. Along the southeastern segment of the fault, the latest unknown-age rupture is about 65 km long and has a maximum left-lateral coseismic displacement of 5.3 m, and its corresponding earthquake is estimated to be as large as about 7.3 of moment magnitude. Based on relevant investigation, an inference has been drawn that the later two large earthquakes probably occurred in 1854 and 1866, respectively. These demonstrate that the individual segments of the studied Garzê-Yushu fault are all able to produce large earthquakes.

     

Estimation of the 2001 Kunlun earthquake fault slip from GPS coseismic data using Hori's inverse method

The Horios inverse method based on spectral decomposition was applied to estimate coseismic slip distribution on the rupture plane of the 14 November 2001 <i<M</i<<sub<S</sub<8.1 Kunlun earthquake based on GPS survey results. The inversion result shows that the six sliding models can be constrained by the coseismic GPS data. The established slips mainly concentrated along the eastern segment of the fault rupture, and the maximum magnitude is about 7 m. Slip on the eastern segment of the fault rupture represents as purely left-lateral strike-slip. Slip on the western segment of the seismic rupture represents as mainly dip-slip with the maximum dip-slip about 1 m. Total predicted scalar seismic moment is 5.196?×10<sup<20</sup<N·m. Our results constrained by geodetic data are consistent with seismological results.     

龙门山断裂带大地震孕震环境的岩石磁学证据

地震断裂带的孕震环境对于研究地震的发生至关重要.本文以汶川地震断裂带科学钻探2号（WFSD-2）钻孔岩心中的假玄武玻璃、碎裂岩及其围岩为研究对象,通过岩石磁学测试,并结合显微结构观察探讨龙门山断裂带大地震的孕震环境.WFSD-2岩心碎裂岩中的假玄武玻璃是龙门山断裂带曾经发生过大地震活动的岩石学证据,假玄武玻璃具有高磁化率特征,而碎裂岩的磁化率值与围岩相似,假玄武玻璃中的新生磁铁矿是其高磁化率值异常的重要原因之一.假玄武玻璃中较少量的新生磁铁矿暗示了假玄武玻璃的生成环境为含氧量较低的高温还原环境.大地震断裂的摩擦热是改变龙门山断裂带中假玄武玻璃岩石磁学特征的主导因素,流体作用较弱.无高磁化率异常的碎裂岩经历的温度小于300℃,推测假玄武玻璃的生成深度较深.WFSD-2岩心中20余层假玄武玻璃脉体证明映秀—北川断裂带是一条长期活跃的断裂带,龙门山断裂带上曾经发生了多次大地震断裂活动,这些大地震可能发生在深度较大、流体作用较弱的还原性孕震环境中.

     

运用古地震数据评价东昆仑断裂带东段未来百年的强震危险性

通过收集、整理和分析青藏高原东北部22条断裂带上古地震定量数据,拟定了该区的地震复发概率密度函数.根据此函数对区内东昆仑断裂带东段不同段落上未来100年内强震原地复发的条件概率进行了初步研究.结果表明,该断裂带上自西向东的3个破裂段中,玛沁段和塔藏段未来20、50、100年的复发概率值介于0.76%~7.36%之间,玛曲段未来20、50年的复发概率值介于2.0%~5.26%,属于低概率事件;玛曲段未来100年的复发概率值为10.82%,属于中概率事件;整个段未来100年内至少发生一次7级以上强震的联合概率可达21.87%,属于中概率事件.考虑到概率模型的不确定性,进一步对各段进行了危险性的定性分类,综合评价认为玛沁段在未来百年内发生大震的危险性较低,玛曲段和塔藏段未来百年发生大震的危险性较高.最后将本文拟合的概率密度函数与传统通用函数计算的条件概率值进行比较,发现通用的复发概率函数随着自变量t/R的增大,因变量P的反映不如本文拟合函数的敏感.     

运用古地震数据评价东昆仑断裂带东段未来百年的强震危险性

通过收集、整理和分析青藏高原东北部22条断裂带上古地震定量数据,拟定了该区的地震复发概率密度函数.根据此函数对区内东昆仑断裂带东段不同段落上未来100年内强震原地复发的条件概率进行了初步研究.结果表明,该断裂带上自西向东的3个破裂段中,玛沁段和塔藏段未来20、50、100年的复发概率值介于0.76%~7.36%之间,玛曲段未来20、50年的复发概率值介于2.0%~5.26%,属于低概率事件;玛曲段未来100年的复发概率值为10.82%,属于中概率事件;整个段未来100年内至少发生一次7级以上强震的联合概率可达21.87%,属于中概率事件.考虑到概率模型的不确定性,进一步对各段进行了危险性的定性分类,综合评价认为玛沁段在未来百年内发生大震的危险性较低,玛曲段和塔藏段未来百年发生大震的危险性较高.最后将本文拟合的概率密度函数与传统通用函数计算的条件概率值进行比较,发现通用的复发概率函数随着自变量t/R的增大,因变量P的反映不如本文拟合函数的敏感.