The destructive earthquakes listed in the "Chronological Scientific Tables (Rika Nenpyo)" and those described in this report are shown (those with the largest magnitude in the case of earthquake swarms) in the figure on the primary destructive earthquakes in each region and surrounding areas. In some cases, earthquake swarms are shown even if they were not destructive.

For earthquakes of a certain magnitude -- M 7.3 or greater for earthquakes at sea and M 6.7 for inland earthquakes -- we have shown the source region whenever known. As a rule, we have used the wave source region from Hatori's papers on earthquakes at sea, and the fault models from the "The Parameter Handbook about the Earthquake Fault in Japan" for inland earthquakes.

For those earthquakes occurring since 1980 for which no fault model exists, we have estimated the source region based on the aftershock distributions observed by research organizations and universities.

We used the "Chronological Scientific Tables" for the location of the hypocenter of earthquakes occurring before 1884; Utsu's papers for earthquakes occurring from 1885 to 1925; and data from the Japan Meteorological Agency (JMA) for earthquakes occurring after 1926.

Generally, we use the figures from the Chronological Scientific Tables for the magnitude (M) of the earthquake. For those earthquakes not listed, we use data for locations of the hypocenter. Estimates are sometimes used for the magnitude of earthquakes known from historical data, i.e., M 7.9 - 8.2. In these cases, the values of the magnitude shown in the figures were obtained from the average value for the interval rounded off from the second decimal place. Also, for the values of magnitudes in which fractions are used, such as M 6 1/4, we rounded off from the second decimal place after conversion to decimal fractions. Finally, we used the lower limit for magnitudes expressed by the phrase, "M 7.5 or greater".

The active faults are those shown in the book "Active Faults in Japan (Revised Edition)" with a degree of certainty of I or II. Please note that some faults have been removed or their degree of certainty modified due to the current information (See the text).

The topographical information is based on the "Digital Map 250m Grid (Elevation)".

The location of volcano is based on the "National Catalogue of the Active Volcanoes in Japan" (Second Edition).

For more details, refer to the references (Appendix 3).

Figures showing topography and active faults

The figures showing the topography and active faults are taken from those included in a degree of certainty I or II in the book "Active Faults in Japan (Revised Edition)". Please note that some faults have been removed or their degree of certainty modified due to the availability of new information (See the text).

The topography is based on the "Digital Map 250m Grid (Elevation)".

For more details, refer to the references (Appendix 3).

Figures showing extension and compression

Each region has a figure that indicates extension and compression over a roughly 100-year period and a 10-year period. The extension and compression for the most recent 100-year period were determined by obtaining the difference between the survey taken in the late 19th century (Meiji era) and the most recent measurements. It requires several years to survey an entire region, so the measurement period of each region differs. Strictly speaking, there are also differences in the survey period for points within the same region. Therefore, we use the descriptive expression, "roughly 100-year period". These same conditions apply for extension and compression for the roughly 10-year period.

Figures showing seismic intensity distribution

We show the seismic intensity distribution in each region for those earthquakes cited as destructive. The data for seismic intensity is generally taken from the Japan Meteorological Agency (JMA). For older earthquakes, we have also used such data as the "Materials for Comprehensive List of Destructive Earthquakes in Japan (Revised and Enlarged Edition)". We use those figures showing seismic intensity distribution in the original text where these are available. Where these figures do not exist, we have quoted contours based on seismic intensity data.

Graphs showing aftershock frequency

We provide graphs showing trends in aftershock frequency for those earthquakes cited as examples of destructive earthquakes. In some instances, the frequency of aftershocks shown is that observed at an observation point (or the frequency of sensing aftershocks in the case of felt earthquakes). Also, in some instances, the number of earthquakes indicated is that detected by the seismological observation network of JMA. For the observations by the JMA's network, the numbers indicate the frequency of the aftershocks that can be felt at any observation station.