“ Active fault” is a technical term used in the field of geosciences, but it has become familiar among the Japanese society since the January 17,1995 Kobe earthquake, which attacked the southern part of Hyogo Prefecture, resulting in a terrible disaster, because the seismogenetic fault for that earthquake just appeared on the already mapped active fault. The decade after the Kobe earthquake can be defined as“ the time when active fault has commonly has been accepted and its significance has been generally understood”. One of important concept is that the active faults have been repeatedly occurred on the same fault traces, and then those traces will be active in future. Thus we need to know the nature, magnitude and frequency of faulting for the understanding of future earthquakes as the fundamental data to reduce the possible disaster. In this paper I review the active fault research introduced by mass media and mention what kind of information on active faults are necessary for confirming the safety of critical facilities or safe town planning. In 2007, Japanese Society of Active Fault Studies was established, as the first academic society of active fault studies in the world. I expect that this society can contribute for disaster mitigation, urban design, social infrastructures, and safety for nuclear power plant, based on accurate scientific data.
