Geomorphological Study for Better Prediction of Large Earthquakes Generated by Active Faults

准确评价活动断层在重新激活引起大地震时的孕震行为的基础资料是活动断层的几何形状、凹凸不平的位置和破裂起爆、破裂传播方向等。为了获得这些数据，我们编制了日本98个主要活动断裂带的断层滑动分布数据库，该数据库由地震研究促进总部地震研究委员会为日本国家地震危险区图选择。数据收集自2001年以前关于这些断层的文章和报告以及“日本数字活动断层图”（Nakata and Imaizumi， 2002年编辑），并编译为Excel文件，并处理成GIS格式。该数据库包含位置、垂直和水平滑动、估计滑动率以及断层相关特征及其年龄的测量方法。该数据库是同类产品中的第一个产品，但还远远没有达到实质性的水平，特别是在滑动数据上。然而，我们认为这个数据库对于大致定位活动断层上的凸起是有用的，可以更好地估计强地面运动。我们还对大尺度航空照片进行了仔细的解释，以便更详细地绘制活动断层图，重视微小的构造地貌，并获得了与未来地震震级密切相关的活动断层范围的重要信息。利用激光成像技术获得典型逆断层（日本东北部的仙雅断层）和走滑断层（日本中部的阿德拉断层）的综合特征，并测试了几种从详细的DEM图像中获取断层滑动的方法。为了寻找滑移率分布较大的剖面，我们沿断层（带）分析了滑移率分布，并假设该剖面可能与地下断裂面上的凸起位置一致。根据活动断层的分支特征和沿断层垂直滑动分布的特征模式等几何标准，作为预测未来地震地表破裂起始位置和破裂长度的工具（Nakata和Goto(1998)），我们提出了未来大地震的动态断层模型。少

Basic data for accurate assessment of seismogenic behavior of active faults when re-activated causing large earthquakes, are geometry of active faults, location of asperities and rupture initiation, direction of rupture propagation, etc. In order to obtain these data, we compiled a database on fault slip distribution along the 98 major active fault zones in Japan selected for National Seismic Hazard Maps for Japan by The Earthquake Research Committee, the Headquarters for Earthquake Research Promotion. Data were collected from articles and reports on these faults before 2001 as well as 'Digital Active Fault Map of Japan' (Nakata and Imaizumi, edited 2002), and compiled as an Excel file, and processed into GIS format. The database contains location, vertical and horizontal slips and estimated slip rates together with method of measurement on fault related features and their ages.This database is the first product of its kind, but is still far from substantial level, especially on slip r … More ate data. However, we believe that this database is useful to roughly locate asperities on active faults for better estimation of strong ground motion.We also carried out careful interpretation of large-scale air-photographs for more detailed mapping of active faults, paying much attention to minute tectonic landform and obtained important information about extent of active faults, that is closely related to the magnitude of future earthquakes.Laser imagery technique is applied to obtain comprehensive features of typical reverse fault (Senya fault in NE Japan) and strike-slip fault (Adera fault in Central Japan), and tested several methods for obtaining fault slip from detailed DEM images.We analyzed slip rate along faults (zones) in order to find section(s) of large slip rate distribution, presuming that section(s) may be coincide with location of asperities on subsurface fault plane. Base on geometric criteria such as branching features of active fault traces and characteristic pattern of vertical-slip distribution along the fault traces as tools to predict location of surface rupture initiation and rupture length of future earthquakes (Nakata and Goto (1998)), we proposed dynamic fault model for future large earthquakes. Less