Detection of Kuril subduction-zoneearthquakes from remote historic recordsin Honshu, Japan, between 1656 and 1867

K Satake K Satake

doi:10.4401/ag-3306

Abstract

Earthquakes before A.D. 1800 along the Southern Kuril trench, although before the start of written history on nearby islands, probably account for some of the earthquakes noted by local records in Honshu, hundreds of kilometers to the southwest. Earthquake historians have identified about 4800 felt earthquakes in Edo (present Tokyo) and about 3000 felt reports in selected local government records in Tohoku, northern Honshu, for the years A.D. 1656-1867. On the average, 19 earthquakes per year were felt in Edo. Of the Tohoku records, 361 (an average nearly 2 per year) were felt at multiple Tohoku locations; 95 of these (0.4 per year) were also felt in Edo. Since 1926, Tokyo has had a yearly average of 15 felt earthquakes with seismic intensity 2 or more on the Japan Meteorological Agency scale (corresponding to III or more on Modified Mercalli scale). For Tohoku the average annual frequency is about 4. Among them, an average of 0.6 events per year also reached intensity 2 in Tokyo. About one quarter of these events occurred in the southern Kuril trench. If the seismicity is temporally constant, about 80 of the earthquakes recorded in 1656-1867 probably had a Kuril origin.

Highlights

Japan is one of the most seismically-active regions in the world, surrounded by four tectonic plates: the Pacific, Philippine Sea, Eurasia and North America plates
On the basis of such historical documents, recurrence of great earthquakes along the Nankai trough with approximately 100 year intervals has been inferred from historical documents (Imamura, 1928; Ando, 1975)
In A.D. 1603, the Shugun established a centralized government in Edo, and each local government started keeping official records

Summary

Introduction

Japan is one of the most seismically-active regions in the world, surrounded by four tectonic plates: the Pacific, Philippine Sea, Eurasia and North America plates (fig. 1). The oldest documented earthquakes along the Southern Kuril trench occurred in the 19th century. The oldest record in the Eastern Hokkaido is «Nikkan-ki», the official record of a temple in Akkeshi. It started in A.D. 1804, and reports about 70 earthquakes between 1816 and 1861. Because of the short written history of Hokkaido, it seems difficult to infer the pre-19th century seismicity along the Kuril trench. Great earthquakes along the southern Kuril trench are felt in Tohoku (northern Honshu) and Tokyo, and relatively uniform historical records exist in these regions.

Earthquakes along Kuril subduction zone

Historical records

Modern seismic intensity observations

Aomori

Findings

Edo-period Kuril seismicity