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

为了准确评估活动断裂在重新激活后引发大地震时的孕震行为，基础数据是活动断裂的几何形状、凹凸体和破裂起始位置、破裂传播方向等。为了获得这些数据，我们编制了一个关于日本98个主要活动断裂带的断层滑动分布的数据库，该数据库由地震研究委员会为日本地震研究促进总部为日本国家地震危险图选定。数据收集自2001年前有关这些断层的文章和报告以及《日本数字活动断层图》(Nakata和Imaizumi，2002年编辑)，并编译为Excel文件，并处理为地理信息系统格式。该数据库包括位置、垂直和水平滑动以及估计的滑动速率，以及断层相关特征及其年龄的测量方法。该数据库是此类数据库的第一个产品，但仍远未达到实质性的水平，特别是在滑动r…方面更多ATE数据。然而，我们认为该数据库有助于粗略地定位活动断层上的凹凸体，以便更好地估计强地面运动。我们还对大比例尺航空照片进行了仔细的解释，以更详细地绘制活动断层图，非常关注精细的构造地貌，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。应用激光成像技术获得了典型的逆断层(日本东北部的Senya断层)和走滑断层(日本中部的Adera断层)的综合特征，并对几种从详细DEM影像中提取断层滑动的方法进行了验证，分析了沿断层(带)的滑动速率，以找出大滑动速率分布的断面(S)，假定该断面(S)可能与地下断层面上的凹凸体位置重合。基于活动断裂道的分支特征和沿断裂道的垂直滑动分布特征等几何判据，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。较少

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