A Database of Digitized and Analog Seismograms of Historical Earthquakes in Japan

Seismic and tsunami instrumental observations by seismographs and tide gauges began in Japan in 1875; hence, many analog records of earthquakes and tsunamis are stored at various universities and institutions throughout the country. Re‐examination of historical records using modern waveform analysis methods, high‐performance computing, and current knowledge on seismic velocity structure is expected to produce new results and interpretations of the mechanism of large earthquakes and tsunamis, leading to improved seismic disaster mitigation practices. However, such work requires extensive effort and skills for the digitization of the analog waveforms recorded on papers. To conveniently use the analog seismograms, we currently construct a database of digitized historical records and seismogram image copies of major earthquakes that occurred in Japan (e.g., the 1923 Kanto, 1944 Tonankai, and 1946 Nankai earthquakes). The data can be searched in this database by event, station, and seismograph names. Users can obtain the instrumental response and station information, if available, in addition to the digitized data. We plan to open this database to the public in a few years via the National Museum of Nature and Science and the Earthquake Research Institute of the University of Tokyo. The database on the museum website will be fundamental for outreach activity of seismology for the general public, and the information contained in the database will be useful in various fields such as seismology or earthquake engineering.