Seismicity, deformation and seismic hazard in the western rift of Corinth: New insights from the Corinth Rift Laboratory (CRL)   总被引：1，自引：2，他引：1  

P. Bernard  H. Lyon-Caen  P. Briole  A. Deschamps  F. Boudin  K. Makropoulos  P. Papadimitriou  F. Lemeille  G. Patau  H. Billiris  D. Paradissis  K. Papazissi  H. Castarde  O. Charade  A. Nercessian  A. Avallone  F. Pacchiani  J. Zahradnik  S. Sacks  A. Linde 《Tectonophysics》2006,426(1-2):7

This paper presents the main recent results obtained by the seismological and geophysical monitoring arrays in operation in the rift of Corinth, Greece. The Corinth Rift Laboratory (CRL) is set up near the western end of the rift, where instrumental seismicity and strain rate is highest. The seismicity is clustered between 5 and 10 km, defining an active layer, gently dipping north, on which the main normal faults, mostly dipping north, are rooting. It may be interpreted as a detachment zone, possibly related to the Phyllade thrust nappe. Young, active normal faults connecting the Aigion to the Psathopyrgos faults seem to control the spatial distribution of the microseismicity. This seismic activity is interpreted as a seismic creep from GPS measurements, which shows evidence for fast continuous slip on the deepest part on the detachment zone. Offshore, either the shallowest part of the faults is creeping, or the strain is relaxed in the shallow sediments, as inferred from the large NS strain gradient reported by GPS. The predicted subsidence of the central part of the rift is well fitted by the new continuous GPS measurements. The location of shallow earthquakes (between 5 and 3.5 km in depth) recorded on the on-shore Helike and Aigion faults are compatible with 50° and 60° mean dip angles, respectively. The offshore faults also show indirect evidence for high dip angles. This strongly differs from the low dip values reported for active faults more to the east of the rift, suggesting a significant structural or rheological change, possibly related to the hypothetical presence of the Phyllade nappe. Large seismic swarms, lasting weeks to months, seem to activate recent synrift as well as pre-rift faults. Most of the faults of the investigated area are in their latest part of cycle, so that the probability of at least one moderate to large earthquake (M = 6 to 6.7) is very high within a few decades. Furthermore, the region west to Aigion is likely to be in an accelerated state of extension, possibly 2 to 3 times its mean interseismic value. High resolution strain measurement, with a borehole dilatometer and long base hydrostatic tiltmeters, started end of 2002. A transient strain has been recorded by the dilatometer, lasting one hour, coincident with a local magnitude 3.7 earthquake. It is most probably associated with a slow slip event of magnitude around 5 ± 0.5. The pore pressure data from the 1 km deep AIG10 borehole, crossing the Aigion fault at depth, shows a 1 MPa overpressure and a large sensitivity to crustal strain changes.  相似文献   

Ferguson rock slide buries California State Highway near Yosemite National Park     

Edwin L. Harp  Mark E. Reid  Jonathan W. Godt  Jerome V. DeGraff  Alan J. Gallegos 《Landslides》2008,5(3):331-337

During spring 2006, talus from the toe area of a rock-block slide of about 800,000 m³ buried California State Highway 140, one of the main routes into heavily-visited Yosemite National Park, USA. Closure of the highway for 92 days caused business losses of about 4.8 million USD. The rock slide, composed of slate and phyllite, moved slowly downslope from April to June 2006, creating a fresh head scarp with 9–12 m of displacement. Movement of the main rock slide, a re-activation of an older slide, was triggered by an exceptionally wet spring 2006, following a very wet spring 2005. As of autumn 2006, most of the main slide appeared to be at rest, although rocks occasionally continued to fall from steep, fractured rock masses at the toe area of the slide. Future behavior of the slide is difficult to predict, but possible scenarios range from continued scattered rock fall to complete rapid failure of the entire mass. Although unlikely except under very destabilizing circumstances, a worst-case, rapid failure of the entire rock slide could extend across the Merced River, damming the river and creating a reservoir. As a temporary measure, traffic has been rerouted to the opposite side of the Merced River at about the same elevation as the buried section of Highway 140. A state-of-the-art monitoring system has been installed to detect movement in the steep talus slope, movement of the main slide mass, local strong ground motion from regional earthquakes, and sudden changes in stream levels, possibly indicating damming of the river by slide material.  相似文献   

长白山天池火山的危险性和火山碎屑流灾害评估   总被引：6，自引：0，他引：6  

李春风  吕纪宁 《东北地震研究》1999,15(3):64-73

本文以长白山天池火山１２１５ＡＤ大喷发为参照系,采用了“以古论今”的历史分析方法,对天池火山的危险性和火山碎屑流灾害进行了评估。认为长白山天池火山是具有潜在喷发能力的高危险火山,给出了长白山天池火山的火山碎屑流灾害预测分区图,为各级政府部门合理制定土地使用规划和防灾活动提供了理论依据。  相似文献   

设定地震的分类及其确定方法   总被引：1，自引：0，他引：1       下载免费PDF全文

郭星全  赵文星  雷建设 《地震工程学报》1999,21(1):102-106

讨论了震害预测中的设定地震,将其分为检验型设定地震、预测型设定地震和重现型设定地震,并论述了３种设定地震的确定原则和方法．作者还进一步论述了３种设定地震在不同震害预测方法中的应用  相似文献   

走向21世纪的城市减灾研究     

金磊 《华南地震》1999,19(3):79-84

探索城市的综合减灾能力从而保持城市的可持续发展,是摆在所有城市建设科技工作者及管理者面前的一个重要问题。选取这个问题的一个重要方面即城市灾害现象、致灾因子、城市综合减灾等进行分析,并对２１世纪的中国城市综合减灾提出可供参考的建议。  相似文献   

浙江省文泰震区地震滑坡危险性评估     

李环宇  陈涛  杨福平  陈奇  徐晓桐  戴陈兵  周怀斌 《中国地震》2023,39(3):636-649

地震滑坡灾害的震前预测与震后快速评估已成为减轻地震次生灾害的重要手段之一。本文使用简化Newmark模型,设定地震震级(M_S5.0),利用区域地质图、数字高程模型等基础数据,考虑地形对地震动的放大效应,对文泰震区潜在同震滑坡区域开展评估工作。研究表明,干燥与饱和状态下,设定地震作用下研究区内地震滑坡高危险区均主要分布在距设定震中15km以内的范围内,其分布与区内岩土体处于临界稳定状态的分布趋势相同。区内水库坝址与水库库体未受到潜在同震滑坡的影响,划定的重点关注区内位于潜在滑坡体下方的千秋门村、驮加村、高西村、杜山村、南峤村、包坑村、龙前村、新厂村以及各级公路易受到同震滑坡的影响,应提升重点关注区内承灾体的风险防范能力,尽可能减少潜在同震滑坡对区内生命财产安全造成的威胁。  相似文献   

Modern and historical tropical cyclone and tsunami deposits at the coast of Myanmar: Implications for their identification and preservation in the geological record     

Dominik Brill  Katharina Seeger  Anna Pint  Felix Reize  Kay Thwe Hlaing  Martin Seeliger  Stephan Opitz  Khin Mi Mi Win  Win Thuzar Nyunt  Nilar Aye  Aung Aung  Kyaw Kyaw  Frauke Kraas  Helmut Brückner 《Sedimentology》2020,67(3):1431-1459

The catastrophic storm surge of tropical cyclone Nargis in May 2008 demonstrated Myanmar's exposure to coastal flooding. The investigation of sediments left by tropical cyclone Nargis and its predecessors is an important contribution to prepare for the impact of future tropical cyclones and tsunamis in the region, because they may extend the database for long-term hazard assessment beyond the relatively short instrumental and historical record. This study, for the first time, presents deposits of modern and historical tropical cyclones and tsunamis from the coast of Myanmar. The aim is to establish regional sedimentary characteristics that may help to identify and discriminate cyclones and tsunamis in the geological record, and to document post-depositional changes due to tropical weathering in the first years after deposition. These findings if used to interpret older deposits will extend the existing instrumental record of flooding events in Myanmar. Evaluating deposits that can be related to specific events, such as the 2006 tropical cyclone Mala and the 2004 Indian Ocean tsunami, indicates similar sedimentary characteristics for both types of sediments. Landward thinning and fining trends, littoral sediment sources and sharp lower contacts allow for the differentiation from underlying deposits, while discrimination between tropical cyclone and tsunami origin is challenging based on the applied methods. The modern analogues also demonstrate a rather low preservation potential of the sand sheets due to carbonate dissolution, formation of organic top soils, and coastal erosion. However, in coastal depressions sand sheets of sufficient thickness (>10 cm) may be preserved where the shoreline is prograding or stable. In the most seaward swale of a beach-ridge plain at the Rakhine coast, two sand sheets have been identified in addition to the deposits of 2006 tropical cyclone Mala. Based on a combination of optically stimulated luminescence, radiocarbon and ¹³⁷Cs dating, the younger sand layer is related to 1982 tropical cyclone Gwa, while the older sand layer is most probably the result of an event that took place prior to 1950. Comparison with historical records indicates that the archive is only sensitive to tropical cyclones of category 4 (or higher) with landfall directly in or a few tens of kilometres north of the study area. While the presented tropical cyclone records are restricted to the last 100 years, optically stimulated luminescence ages of the beach ridges indicate that the swales landward of the one investigated in this study might provide tropical cyclone information for at least the past 700 years.  相似文献