The earthquakes

Here I use the most common name for each earthquake, with major alternative names, if any, given in parentheses in the heading. The lunar date for premodern earthquakes is also given in the heading, using the format year/ month/day. Because the epicenter of many of the earthquakes discussed here was located in or near the Kansai region, I begin with a brief description of the geology of this area.

Japan's Kansai (or Kinki) region, which includes the urban areas of Osaka, Kobe, and Kyoto, sits atop many active faults. It includes the so-called Kinki Triangle Region, defined by points at the edge of Wakasa Bay, Awaji
Island, and the middle of Ise Bay, which contains the highest concentration of active faults in Japan. The tectonic geology of the region is largely a result of the Philippine Sea Plate subducting under the Eurasian Plate. This subduction creates the Nankai Trough in the Pacific Ocean off the coast of the Kansai region and areas to the south. Accumulated strain from plate motion generates three types of earthquakes. The first is ocean trench earthquakes, usually originating in areas off the coast of Mie Prefecture or Wakayama Prefecture. Examples include the 1707 Hōei earthquake and the 1854 Ansei Tōkai-Nankai earthquake. Since the late 1970s, popular fear of another earthquake of this type and the tsunami it would generate has prompted significant government spending on monitoring this region.[1] Next are deep intraplate earthquakes, with focal (origin) points in the part of the Philippine Sea Plate pushing underneath the Eurasian Plate. The third type is inland earthquakes with a relatively shallow focus within the Eurasian Plate.[2]

Keicho-Fushimi (Fushimi-Momoyama), 1596 (Keicho1)/7/13

The Keichō-Fushimi earthquake (around midnight, September 5, 1596) was a shallow inland earthquake of M7.5 with an epicenter near Hirano on the outskirts of Osaka. It caused approximately fifteen hundred deaths and extensive property damage. Efforts to map all the faults under Japan

Map 1 Produced by Jeffrey Smits, Cherokee Drafting Specialists.

After the 1995 Hanshin-Awaji (Kobe) earthquake led to the discovery of the likely cause of the Keichō-Fushimi earthquake: a rupture of the ArimaTakatsuki Fault, possibly in conjunction with the Rokkō-Awaji Island Fault.[3] The keep of Fushimi Castle collapsed, and a falling stone wall killed seventy-three high-ranking ladies-in-waiting and some five hundred maids. Toyotomi Hideyoshi, Japan's ruler at the time, was in the castle and escaped into a courtyard. Many shrines and temples in the area incurred major damage.[4]

Kanbun (Kanbun Omi-Wakasa; Biwakoseigan), 1662 (Kanbun 2)/5/1

Approximately ninety kilometers northwest from the epicenter of KeichōFushimi, another shallow inland earthquake struck around noon on June 16, 1662. The epicenter of the Kanbun earthquake was the western bank of Lake Biwa near the present-day town of Kitahama. Magnitude estimates range from 7.25 to 7.6, and people as far away as Fukuyama and Edo felt this powerful earthquake. Some seismologists posit movement of the Hiruga Fault under Wakasa Bay, followed by movement of the central and northern sections of the Hanaore Fault, which extends from a point north of Kyoto along the western shore of Lake Biwa. In this view, the Kanbun earthquake was a two-stage seismic event, and it may have been two earthquakes in succession. According to Okada Yoshimitsu, movement of the Hanaore Fault and the Lake Biwa West Bank Fault Zone caused the earthquake. Damage was severe across the region, varying significantly as a function of local conditions. Estimates of the death toll for the western shore of Lake Biwa range from seven hundred to one thousand, including about two hundred deaths in Kyoto. The situation in some places, however, was much worse than these overall figures suggest. Landslides buried several villages, wiping out the vast majority of their populations. In Kawamura in the Kutsuki Valley, for example, collapsing mountains buried all of the approximately fifty dwellings, and only thirty-seven of the more than three hundred inhabitants survived.[5]

  • [1] For a critical assessment of modern fears of a Tōkai or Nankai earthquake, see Geller, Jishin yochi, 10–11, 92–98. According to Geller, mentioning the four characters “Tōkai earthquake” functions as “a magic mallet” (uchide no kozuchi) that produces budget allocations. The Great East Japan Earthquake and tsunami renewed fears of Tōkai and Nankai earthquakes. To take one example from popular media, see “Massive Tsunami Projected: Panel Forecasts Nankai Trough Quakes Could Affect 11 Prefectures,” Daily Yomiuri Online, April 2, 2012.
  • [2] Okada Yoshimitsu, Saishin Nihon no jishin chizu (Tōkyō shoseki, 2006), 139–143, and Sangawa Akira, Jishin no Nihonshi: Daichi wa nani o kataru ka (Chūōkōron shinsha, 2007), 34–36. Nankai Trough earthquakes took place in 684, 887, 1009, 1361, 1605, 1854, and 1946. These earthquakes have often occurred in close temporal proximity to ocean trench earthquakes originating in the Sagami Trough off the Izu Peninsula, which are known as Tōkai earthquakes. They occurred in 1096, 1498, 1605, 1707, 1854, and 1944. For more details on Tōkai and Nankai earthquakes, see Tsuji Yoshinobu, “Ansei tōkai, nankai jishin no jitsuzō to senjin no saigai kyōkun,” in Chūō bōsai kaigi, 1854 Ansei tōkai jishin, Ansei nankai jishin hōkokusho (Chūō bōsai kaigi, 2005), 4–5, and Noguchi Takehiko, Ansai Edo jishin: Saigai to seiji kenryoku (Chikuma shobō, 1997), 22.
  • [3] Itō Kazuaki, Jishin to funka no Nihonshi (Iwanami shoten, 2002), 184; Okada, Jishin chizu, 144; and Usami Tatsuo, Nihon higai jishin sōran [416]–2001, saishin-ban (Tōkyō daigaku shuppankai, 2003), 52.
  • [4] Okada, Jishin chizu, 144, Itō; Jishin to funka no Nihonshi, 182, 184; and Usami, Higai jishin, 51–52. For reports on damage to the castle, see DNJS, vol. 1 (kō), 157–158, 191. For the specific figures of seventy-three ladies-in-waiting and five hundred maids killed, see pages 202–203.
  • [5] Okada, Jishin chizu, 145; Itō, Jishin to funka no Nihonshi, 185; Sangawa, Jishin no Nihonshi, 121–123, 125; Usami, Higai jishin, 57–58; and Kitahara Itoko, “Saigai to jōhō,” in Kitahara Itoko, ed., Nihon saigaishi (Yoshikawa kōbunkan, 2006), 232. For a detailed analysis of the damage from this earthquake, see Chūō bōsai kaigi, 1662 Kanbun Ōmi-Wakasa jishin hōkokusho (Mizuho jōhō sōken kabushikigaisha, 2005). For extensive diary and other accounts of the earthquake and its damage, see DNJS, vol. 1 (kō), 246–255. Regarding the buried villages, see page 251 (entry “Rakuho zatsudan ichigenshū”).
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