1 Introduction


The Southern Hyogo Prefecture Earthquake (Hyogo-ken Nanbu Earthquake) of January 17, 1995 left behind an immense trail of destruction: by December 26, 1996 of the following year, the earthquake had claimed 6,427 lives with more than 40,000 people sustaining serious injury. After the earthquake, many people in the area said that they had no idea such a large earthquake could occur in Kobe, which has revealed the importance of acquiring basic knowledge about earthquakes. In response, the Earthquake Research Committee of the Headquarters for Earthquake Research Promotion compiled this report on earthquakes. The objective is to provide accurate information on earthquakes in an easy-to-understand manner.

After the Southern Hyogo Prefecture Earthquake, a Special Measures Law on Earthquake Disaster Prevention was enacted to shore up existing measures against earthquake damage. The Headquarters for Earthquake Research Promotion was established based on this legislation, and a new organization was launched to promote surveys and research on earthquakes. Within this organization, the Earthquake Research Committee is responsible for collecting and organizing the results of seismic surveys, conducting research earthquakes, and analyzing and evaluating this information. One of this committee's objectives is to gain a better understanding of the characteristics of seismic activity in Japan, a second is to evaluate the possibility of earthquakes occurring over the long term. Accordingly, the Subcommittee for Long-Term Evaluation was formed in December 1995. This subcommittee divided Japan into three regions, and established special panels to compile the characteristics of seismic activity in each region.

Chapter 2 of the present report provides an overview of seismic activity throughout Japan, along with some basic information on earthquakes. In Chapters 3 to 9, Japan is divided into the Hokkaido, Tohoku, Kanto, Chubu, Kinki, Chugoku-Shikoku, and Kyushu-Okinawa regions. Each chapter begins with an overview of seismic activity in each region. This is followed by a description of the type of destructive earthquakes that have occurred in each region, an overview of the primary destructive earthquakes that have occurred in each region, and a description of the characteristics of each prefecture (as for Hokkaido, of each district). We also have provided an explanation of technical terms, and appended diagrams for the reader's reference.

One salient feature of this report is that we have described destructive earthquakes from the perspective of each prefecture, or each area in Hokkaido's case. * In addition, we have attempted to provide a comprehensive account of the subject by correlating information obtained from separate fields of earthquake study, including the history of past earthquakes, active faults, and crustal movements. A chart and explanation of terms is provided to make this technical material as easy to understand as possible. Please note that although the information in this report is all up to date, we provide several differing explanations for those points that have yet to be conclusively evaluated.

We expect that future long-term progress in earthquake research will result from the new technology and observational systems now in place. The results of these investigations will be incorporated into this report as soon as they become available.

With improvements in seismological survey and observation under way, progress is anticipated in seismology and other related sciences. This report will be reviewed and revised whenever such occasion arises.

We hope this report will be used widely, and not only by members of local government responsible for dealing with disasters.

* The English edition of this report does not include a description of the characteristics of each prefecture.