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Kenai, located on the west coast of the Kenai Peninsula, Alaska, subsided during the great earthquake of AD 1964. Regional land subsidence is recorded within the estuarine stratigraphy as peat overlain by tidal silt and clay. Reconstructions using quantitative diatom transfer functions estimate co‐seismic subsidence (relative sea‐level rise) between 0.28±0.28 m and 0.70±0.28 m followed by rapid post‐seismic recovery. Stratigraphy records an earlier co‐seismic event as a second peat‐silt couplet, dated to ~1500–1400 cal. yr BP with 1.14±0.28 m subsidence. Two decimetre‐scale relative sea‐level rises are more likely the result of glacio‐isostatic responses to late Holocene and Little Ice Age glacier expansions rather than to co‐seismic subsidence during great earthquakes. Comparison with other sites around Cook Inlet, at Girdwood and Ocean View, helps in constructing regional patterns of land‐level change associated with three great earthquakes, AD 1964, ~950–850 cal. yr BP and ~1500–1400 cal. yr BP. Each earthquake has a different spatial pattern of co‐seismic subsidence which indicates that assessment of seismic hazard in southern Alaska requires an understanding of multiple great earthquakes, not only the most recent. All three earthquakes show a pre‐seismic phase of gradual land subsidence that marked the end of relative land uplift caused by inter‐seismic strain accumulation. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
3.
lvaro Gonzlez Miguel Vzquez-Prada Javier B. Gmez Amalio F. Pacheco 《Tectonophysics》2006,424(3-4):319
Numerical models are starting to be used for determining the future behaviour of seismic faults and fault networks. Their final goal would be to forecast future large earthquakes. In order to use them for this task, it is necessary to synchronize each model with the current status of the actual fault or fault network it simulates (just as, for example, meteorologists synchronize their models with the atmosphere by incorporating current atmospheric data in them). However, lithospheric dynamics is largely unobservable: important parameters cannot (or can rarely) be measured in Nature. Earthquakes, though, provide indirect but measurable clues of the stress and strain status in the lithosphere, which should be helpful for the synchronization of the models.The rupture area is one of the measurable parameters of earthquakes. Here we explore how it can be used to at least synchronize fault models between themselves and forecast synthetic earthquakes. Our purpose here is to forecast synthetic earthquakes in a simple but stochastic (random) fault model. By imposing the rupture area of the synthetic earthquakes of this model on other models, the latter become partially synchronized with the first one. We use these partially synchronized models to successfully forecast most of the largest earthquakes generated by the first model. This forecasting strategy outperforms others that only take into account the earthquake series. Our results suggest that probably a good way to synchronize more detailed models with real faults is to force them to reproduce the sequence of previous earthquake ruptures on the faults. This hypothesis could be tested in the future with more detailed models and actual seismic data. 相似文献
4.
The area of Serravalle, sited in the northern part of the town of Vittorio Veneto (TV), NE Italy, has been the target of a
seismic microzonation campaign. 10 seismic stations have been deployed for a 7 months period to record in continuous mode.
Three stations were installed on bedrock outcrops and seven on sedimentary sites with variable cover thickness. Spectral analyses
have been performed on the collected data-set using the Generalized Inversion Technique (GIT, e.g. Andrews, 1986). In particular,
spectral ratios have been calculated for each station relatively to the average of the three reference, bedrock sites. The
spectral ratios provide quantitative estimates of the seismic motion amplifications which occur in each of the monitored sites.
Two sites show high values of amplification, 5 times larger than signal amplitude at the reference sites, in correspondence
of well discernible peak frequencies of 5 Hz. Results for the other stations show smaller amounts of site amplification spreading
over a broad range of frequencies. Sites where the highest amplifications were recorded all lie on the left bank of the Meschio
River and in areas farther away from its outlet into the plain correlating with the presence of thick layers of Quaternary
deposits. 相似文献
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6.
The Dahuiyeh (Zarand) earthquake of 2005 February 22 in central Iran: reactivation of an intramountain reverse fault 总被引:3,自引:0,他引:3
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8.
宁波台矿泉井水温异常与萨尔瓦多8.0级地震的关系 总被引:10,自引:2,他引:10
2001年1月9日起开始宁波台矿泉井井水温度出现异常,通过检查、分析后认为很可能与萨尔瓦多8.0级地震有关系。从日均值图上看,异常在震前6天开始出现,至震前1天达到最大,表现为打破正常的波动规律,呈负异常;从整点测值图看,主要是震前36小时出现负阶跃。分析认为出现的水温异常可能是一种地震前的长周期波通过上地幔或软流层传播而至,间接地影响地下流体发生微小的温度变化。 相似文献
9.
采用一致的地震震相和台网布局,应用昆明数字地震台网资料,对2002年月1月4日-1月7日的漾濞地震及序列作进一步核定,得出了更精确的地震震源位置,并作出三维空间图。 相似文献
10.
Masao Komazawa Hitoshi Morikawa Kajuro Nakamura Junpei Akamatsu Keiichi Nishimura Sumio Sawada Ayfer Erken Akin Onalp 《Soil Dynamics and Earthquake Engineering》2002,22(9-12):829-836
The 1999 Kocaeli earthquake brought serious damage to downtown of Adapazari. To study why strong motions were generated at the town, a bedrock structure was investigated on the basis of Bouguer gravity anomaly, and SPAC and H/V analyses of microseisms. It was revealed that, the basin consists of three narrow depressions of bedrock with very steep edges, extending in E–W or NE–SW directions along the North Anatolia faults, and the depth to bedrock reaches 1000 m or more. Downtown of Adapazari is located 1–2 km apart from the basin-edge. It is considered that, the specific configuration of bedrock amplifies ground motions at the downtown area by focusing of seismic waves and/or interference between incident S-waves and surface-waves secondarily generated at the basin-edge. Studying 3D bedrock structure is an urgent issue for microzoning an urban area in a sedimentary basin. 相似文献