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161.
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郭燕平 《地震地磁观测与研究》2008,29(4):116-120
据中国地震局地球物理研究所中国数字地震台网数据管理中心(CDSNDMC)美国地震学联合研究会数据管理中心(IRISDMC)得到的最新地震资料统计,2008年5月全球范围内共发生M≥5.0地震151次。M5~5.9中强震139次,其中M5~5.5地震116次,M5.6~5.9地震23次;M6.0~7.9强震12次,其中M6.0~7.0地震11次,M7.1~7.9地震1次。最大的一次地震发生在中国四川,发震时间2008年5月12日06:28:01.5700,MW-7.9。全球发生的151次j坦≥5.0地震中有119次发生在东半球,32次发生在西半 相似文献
163.
2008年5月12日四川省汶川县(31.0°N,103.4°E)发生8.0级强烈地震.这是我国建国以来破坏性较大的一次地震.研究该地震发生前川滇地区构造活动及区域应力特征,认识地震孕育、发生和震后调整的过程及对未来地震形势的判定具有十分重要的意义. 相似文献
164.
2008年3月30日16时33分,甘肃肃南发生Ms=5地震,微观震中在(38.0°N,102.0°E).甘肃地震速报台网给出的地震参数:震中(37°55′N,101°55′E),震级帆5.8(Ms5.5),震源深度h=27km.这是继2003年山丹一民乐6.1级地震后,河西走廊中强地震平静4年半的一次5级地震. 相似文献
165.
The temporal and spatial distribution characteristics of earthquakes in the Ordos block are studied by using historical earthquake data,instrument data of the regional seismic network around the Ordos block and the historical felt earthquake data,and the relationship between seismicity in the Ordos block and seismicity around the Ordos block is discussed. The result shows that the Ordos block is a typical moderate-strong earthquake active region where many M_S≥5.0 destructive earthquakes have occurred. The temporal and spatial distribution of earthquakes in the Ordos block is asymmetrical. The temporal distribution of earthquakes shows a periodic characteristic and the activity of earthquakes in the southeastern Ordos block is higher than in the northwest Ordos block. The M_S≥5.0 moderate size earthquakes in the Ordos block are controlled by the M_S≥6.0 earthquake around the Ordos block. 相似文献
166.
The M8.0 Wenchuan earthquake occurred on the Longmenshan fault zone. Based on field investigation of the surface rupture and focal mechanism study of the aftershocks, we discuss the geological relationship of the main, secondary and triggered ruptures. The main rupture is about 200km long and can be divided into the south part and the north part. The south part consists of two parallel fault zones characterized by reverse faulting, with several parallel secondary ruptures on the hanging wall of the main fault, and the north part is a single main fault zone characterized by lateral strike-slip and reverse faulting. Compared to a 300km long aftershock distribution, the surface rupture only occupies 200km, and the remaining 100km on the northeast of the main rupture was triggered by aftershocks. Study on the ruptures of this earthquake will be useful for studying the earthquake risk evolution on the Longmenshan fault system. 相似文献
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Variability in rainfall threshold for debris flow after the Chi-Chi earthquake in central Taiwan, China 总被引:6,自引:0,他引:6
The purpose of this study is to analyze variability in rainfall threshold for debris flow (critical rainfall for debris flow triggering) after the ML 7.3 Chi-Chi earthquake in central Taiwan in 1999. Two study sites with different geological conditions were surveyed in the earthquake area. Streambed surveys were conducted to continuously monitor debris flows between 1999 and 2006. During the 7-year study period, every debris flow event was identified, and the streambed characterized. Results show that the rainfall threshold for debris flow was remarkably lower just after the Chi-Chi Earthquake, but gradually recovered. To date, this rainfall threshold is still lower than the original level prior to the earthquake. This variability in rainfall threshold is closely related to the mount of sediment material in the initiation area of debris flow, which increased rapidly due to landslides resulting from the earthquake. With the increase in sediment material, the rainfall threshold was lowered severely during the first year following the Chi-Chi earthquake. However, heavy rainfalls mobilized the sediment material, causing debris flows and transporting sediment downstream. With the decrease in sediment material, the rainfall threshold recovered gradually over time. Furthermore, debris flows occurred only in the subbasins that had sufficient sediment material to cause significant movement. Hence, these results confirm that the sediment material in the initiation area of debris flow is a crucial component of the rainfall threshold for debris flow. 相似文献
170.