Two observations about Japan are relevant. First, Japan has by far the longest written record of any place along the Pacific Rim, so that an earthquake on the Cascadia subduction zone in AD 1700 could be dated by the tsunami it generated, which was recorded in Japan. Second, Japanese tectonics is controlled by two subduction zones that intersect in a T: a trench–trench–trench triple junction southeast of Tokyo (Figure 9.1). The Japanese began recording earthquakes and tsunamis 13 centuries ago in southwest Japan, around their ancient capitals of Kyoto and Nara, in the upper plate of the Nankai subduction zone. The first earthquake recorded in a historical document struck in AD 416. They completed their first (although non-scientific) catalog of earthquakes in AD 900 as part of the chronicles recording their national history, Ruiju Kokushi (Classified National History; cf. Ishibashi, 2004). The most recent update was provided by Usami (2003).
For most of their written history, earthquakes and tsunamis were to be endured and were even the subjects of classical Japanese painting. In 1868, the old feudal government of Japan was brought down, and the Meiji Restoration began, with the objective of raising Japanese society up to the technological standards of the Western world. Japanese students were sent to study overseas, and foreign experts were employed to bring Japanese science up to Western standards. Japan’s problems with earthquakes were brought to the fore by the Ansei subduction-zone earthquakes that had heavily damaged southwest Japan in 1854. The first instrumental observations were made in Tokyo in 1872 by a Dutch scientist, G.F. Verbeek, and a German meteorologist, E. Knipping. Following a moderate-size earthquake in Yokohama of M 5.5–6 on 22 February 1880, the Seismological Society of Japan (SSJ) was founded on 26 April 1880, the world’s first academic society dedicated to the study of earthquakes. This was a landmark event; by the end of 1881, more than half the members of the society were foreigners. John Milne, employed by the Meiji government, had a major role in the foundation of the SSJ. The study of earthquakes was facilitated by Japan’s long tradition of collecting and recording information about earthquakes for more than 1100 years.