Evaluation of fault activity along the major active fault zone based on new and detail fault data

活断层的位置是过去大地震活动、陆地地震预报和减轻地震灾害的重要资料之一。即使在地震大国日本，在1995年科比大地震之前，人们对活动断层的危险性也没有很好的认识。为了提供有关活断层的基本信息，如其分布和特征活动，我们重新解释了日本的航空照片，并描绘了活动断层痕迹的详细位置和相关信息。活动断层是指在第四纪晚期以1000 ~ 10000年的间隔反复活动，在地表形成与断层相关的明显构造特征的断层。2002年出版了1：25000的《日本第四纪逆冲断层图集》和《日本活动断层数字地图》。这些图为我们提供了关于其位置和活动特征的详细信息，为其他科学领域和减轻地震灾害提供了基础数据。但应注意的是，活动断裂的“活动”标准和编图目的各不相同，与以往的编图不同，有关活动断裂的特征和发震机制的问题还有待进一步研究：（1）断裂活动的复发间隔时间是否一致;（2）每个断层的位移量分布是否具有特征性，（3）在一次地震中，一条长的活动断层有多少段，或有多少组断层;四、如何通过地震反射剖面的研究来区分主断层和副断层，以及地表活动断层与地下发震断层的关系和他们的地质资料

The location of active faults is one of the most important data for large seismic activities in the past, earthquake prediction on land and the relevant seismic hazard mitigation. Even in an earthquake country Japan, danger of active faults was not well understood among the people before 1995 Kobe earthquake. In order to provide the fundamental information regarding active faults such as their distribution and characteristic activities, we have re-interpreted air-photographs in Japan and depicted the detailed location of active fault traces together with related information. We defined active faults as faults that have repeatedly moved during the late Quaternary with intervals of one thousand to ten thousand years forming distinctively fault-related tectonic features on the surface.In 2002, "Atlas of Quaternary Thrust Faults in Japan" and "Digital Active Faults Map of Japan" were published in the scale of 1:25,000. These maps provide us with detailed information regarding their location and characteristic of fault activities for basic data of other science fields and seismic hazard mitigation. It is, however, important to know that criteria as "active" for the active faults and aims for compilation of the maps vary each other as well as from previously published maps.We need to study further problems and questions concerning the characteristics of active faults and the mechanism of the occurring of earthquake ;1) whether the recurrence interval of faulting has been uniform over time or not ;2) whether or not each fault has a characteristic distribution of the amount of displacement ;3) how many segments divide a long active fault or how many faults group in a particular earthquake ;4) how we can distinguish between the main fault and the subsidiary faultand how active faults on the surface related to underground seismogenic faults through the investigation of seismic reflection profiles and their geological data.