| 断层旋性与地震危险性 |
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| 引用本文： | 郭增建,吴瑾冰.断层旋性与地震危险性[J].地学前缘,2001,8(2):247-252. |
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| 作者姓名： | 郭增建 吴瑾冰 |
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| 作者单位： | 中国地震局兰州地震研究所, |
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| 基金项目： | 地震科学联合基金!资助项目 (19812 1) |
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| 摘 要： | 文中以“平行同旋走滑断层减震”的观点论证了兰州、北京、昆明这些位于强震活动区的大城市今后百年内不会发生 6 .5级以上地震。以“平行异旋走滑断层加震”的观点解释了西南棱形块体北边界和南边界在发生大震方面相互促进的现象。对于由构造分段求震级来说 ,在遇到不同的横交断层作为分段点时 ,还需考虑将来发震时始破裂点的位置以及发震断层的旋性 ,不然就会造成对震级估计不足 ,继而成为抗震建设的潜在不安全因素。在主震后为了预报余震的强度 ,可应用物理学中的科里奥利力理论 ,应用时必须知道断层类型和旋性。对于走滑断层来说 ,左旋余震弱 ,右旋余震强。例如 1997年藏北玛尼 7.5级地震 ,余震仅为 5 .3级 ,震级偏小 ,因主震为左旋的缘故 ;1976年唐山 7.8级地震 ,余震可达 7.1级 ,因主震是右旋。对于逆断层来说 ,上盘错动方向在当地子午面左侧者余震强度大 ,在右侧者余震强度弱。据此讨论了 1999年台湾南投 7.6级大震余震强度达 7.1级是因为主震为逆断层 ,上盘向西错动。
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| 关 键 词： | 同旋与减震 异旋与加震 构造分段与始破裂点 科里奥利力 余震强度 |
| 文章编号： | 1005-2321(2001)02-0247-06 |
| 修稿时间： | 2000年9月15日 |
FAULT LATERAL AND EARTHQUAKE RISK |
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| GUO Zeng-Jian,WU Jin-bing.FAULT LATERAL AND EARTHQUAKE RISK[J].Earth Science Frontiers,2001,8(2):247-252. |
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| Authors: | GUO Zeng-Jian WU Jin-bing |
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| Abstract: | Based on the viewpoint of reducing earthquake intensity for parallel strike faults with the same lateral, the authors demonstrated that there will be no earthquakes with magnitude more than 6.5 in the big city such as Lanzhou, Beijing and Kunming, for a hundred years in the future. From the viewpoint of strengthening earthquake for parallel strike faults with different lateral, the mutual promotion of big earthquake occurrence on both the north and south side of the southwest rhombus block has been explained. For determining earthquake magnitude by means of tectonic segmentation and for identifying the point where a seismogenic fault intersects a transverse fault whether belongs to a segmentation point, it is necessary to take into account the uncertainty of the beginning point of the crack and the fault lateral for an earthquake occurs in the future, otherwise, a potential danger may hide in antiseismic construction because of insufficient assessment of the earthquake magnitude. In order to predict aftershock’s magnitude after a mainshock, the authors suggest that the Corioli force effect should be known based on the fault type and fault lateral. For a strike fault, the magnitudes of aftershocks of the fault with left lateral are weaker, and the magnitudes of aftershocks of the fault with right lateral are stronger. For example, the 1997 Mani earthquake (Ms = 7.5 ) in north Tibet had a maximum aftershock with magnitude of 5.3, which was too small, because the mainshock related to the left lateral strike fault; the Tangshan earthquake in 1976 ( Ms=7.8 ) had a maximum aftershock with magnitude of 7.1, because the mainshock related to the right lateral one. For a thrust fault, if the dislocation direction of upper wall is located in the left side of meridian plane ( to view toward north ), the magnitude of aftershock is big, and if that is in the right side, the magnitude of aftershock is small. On the basis of the criterion, the authors discussed that the magnitude of aftershock of the 1999 Nantou earthquake ( Ms=7.6 ) in the Taiwan island was so big that it reached the magnitude of 7.1. The reason is that the mainshock related to the type that the upper wall of the thrust slipped towards the west. |
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| Keywords: | the same lateral and reducing earthquake different lateral and strengthening earthquake tectonic segmentation and beginning point Corioli force magnitude of aftershock |
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