Zenkoji, 1847 (Koka 4)/3/24
Disaster struck Zenkōji and its surrounding areas in present-day Nagano Prefecture around 10 p.m. on May 8, 1847, in the form of a powerful M7.4 shallow-focus inland earthquake. Activity in the Shinano Fault Zone caused the earthquake, whose epicenter was at the western part of the Nagano Basin, near Nagano City. It caused massive destruction and death around the region and was particularly devastating because of the seven to eight thousand pilgrims from all parts of Japan lodged in cramped quarters around Zenkōji, a major temple. The pilgrims were there for a kaichō, the public display of an ordinarily hidden image of Amida and two attendants, which takes place once every seven years at the temple. According to Sangawa Akira's analysis, three to four thousand of these visitors died, many in fires, as did forty-four of the forty-six priests in attendance. The whole area inside and outside the temple was illuminated by lanterns that night, which soon led to a blazing inferno. The other dramatic locus of destruction was an area of the Sai River blocked by a landslide when Mt. Iwakura (also called Mt. Kokuzō) collapsed. Heavy rains on May 22 and 23 swelled the accumulated water. The landslide-dam gave way on the twenty-seventh, causing massive flooding downstream. It was, according to one account, “a disaster of shaking, fire, and water all at once.” These three scourges left as many as twelve thousand dead and caused widespread destruction to fields and structures. Rumors of even higher death tolls circulated in
the days after the main shock. One diary entry for the twenty-ninth day, for example, includes hearsay that several tens of thousands were crushed to death by collapsing houses.
Odawara, 1853 (Kaei 6)/2/2
“The earthquake of the fourth hour of the second day of this month,” began one local account, “did much damage to the castle's keep. The lord's mansion suffered great damage. Nothing remained of the inner wall, the second wall, and the outer wall, which collapsed into the moat. Many pieces of the stone wall ended up in the water, and structures like the connecting watch towers were completely destroyed.” Similarly, a dramatic print entitled Great Earthquake in Sagami (Sagami no kuni ōjishin) showed the area to the north-northeast of the castle in flames and claimed a greatly exaggerated death toll of 3,780. The more likely death toll from this M6.7–7.0 earthquake that struck around 10 a.m. on March 11, 1853, was less than one hundred. Damage to structures was severe in areas with a poor soil base, especially to the north-northeast of the castle. It appears that two main shocks occurred about ten to fifteen seconds apart, and the earthquake generated a tsunami that came ashore at Manatsuru but did little serious damage. Shaking could be felt in parts of Edo and produced some minor damage there.
Iga-Ueno (Ansei Iga), 1854 (Kaei 7/Ansei 1)/6/15
Movement along the Kizugawa Fault Zone in western Mie Prefecture caused the Iga-Ueno earthquake. It was a M7.25 shallow inland earthquake that struck around 2 a.m. on July 9, 1854. Over twenty precursors shook the ground prior to the main shock. Starting on the twelfth day of the lunar month, and again on the thirteenth day, two especially large precursor earthquakes shook the area. Foreshocks combined with aftershocks constituted an ideal combination for putting the population of the area psychologically on edge. One typical account explains that people “only worried, forgetting to eat and sleep” and that “although there has never been a natural disaster in the country of Iga since the age of the deities, the frequency of daily shaking goes up and down, and just tonight there were six or seven shakes.” The death toll was about thirteen hundred, and the shaking destroyed nearly six thousand houses and shops. The earthquake shook Kyoto and Osaka, and it caused significant damage in and around Iga, Nara, and Yokkaichi. In Osaka, many residents near the harbor or waterways
fled to the safety of boats, and because this inland earthquake did not generate a tsunami, they suffered no problems. About six months later, however, during the Ansei Nankai earthquake, such a move proved fatal for several hundred tsunami victims.
-  For an extended discussion of the causes and other seismological details, see Tsukahara Hiroaki, “Zenkōji jishin wa dono yō nishite hasseishita ka,” in Akahane Sadayuki and Kitahara Itoko, eds., Zenkōji jishin ni manabu (Nagano-shi, Japan: Shinano mainichi shinbunsha, 2003), 35–47.
-  Okada, Jishin chizu, 118–119; Itō, Jishin to funka no Nihonshi, 128–142; Sangawa, Jishin no Nihonshi, 164–170; Kitahara, “Saigai to jōhō,” 246–246; Usami, Higai jishin, 137–144; and Shinano mainichi shinbunsha kaihstsukyoku shuppanbu, ed., Kōka yonen Zenkōji daijishin (Nagano-shi: Shinano mainichi shinbunsha, 1977), 111–204. For documentation of the changing condition of the Sai River and other rivers, see “Shinetsu jishinki,” 9, 11–12; “Fujikawa Kan zakki,” 46–47; “Kamahara Dōzan jishin kiji,” 71–78, 92–93; “Kenshūroku,” 105–107, 109–111, 114–115, 120–127; “Nogizono zakki,” 131, 138–139; “Tokutake-shi jishin kiji,” 154–156; “Eikan zasshi,” 256–266, 268–269; “Jishin kiji,” 269–270; “Chisai satsuyō,” 271–272; “Shinshū jishinki,” 276–277, 282–283; “Shinano Daijishinki,” 287–288, 301–307; and “Sinkōkan,” 307–316, all in DNJS, vol. 2 (otsu). Especially useful is Usami’s diagram of the flooding (zu 248-3, Higai jishin, 142).
-  “Tokutake-shi jishin kiji,” in DNJS, vol. 2 (otsu), 156.
-  For an authoritative study of the death and destruction, see Akabane Sadayuki and Inoue Kimio, “Saigai no jōkyō,” in Chūō bōsai kaigi, 1847 Zenkōji jishin hōkokusho (Nihon shisutemu kaihatsu kenkyūsho, 2007), 22–42. See also page 222. Other detailed accounts of the destruction include Shinano mainichi shinbunsha kaihstsukyoku shuppanbu, ed., Zenkōji daijishin, 73–108, and “Akahane Sadayuki, ‘Zenkōji jishin to saigai no zenbō,’” in Akahane and Kitahara, Zenkōji jishin, 9–34.
-  “Koizumi Sōken nichiroku,” in NRJSS, vol. 2, 227.
-  “Odawara hanshi Hoshimi bō-shokan,” in DNJS, vol. 2 (otsu), 327.
-  Nishimaki Kōzaburō, ed. Kawaraban shinbun: Edo, Meiji sanbyaku jiken, vol. 1 (Heibonsha, 1978), 140–141; and Inagaki Fumio, ed., Edo no taihen, ten no kan (Heibonsha, 1995), 58. To view this print, see http://gazo.dl.itc .u-tokyo.ac.jp/ishimoto/1/01–021/00001.jpg.
-  Usami, Higai jishin, 146–148, and Ishibashi Katsuhiko, Daijishinran no jidai (Iwanami shoten, 1994), 8–13.
-  “Jishin kaishō seisetsuroku,” in DNJS, vol. 2 (otsu), 358, 359.
-  Okada, Jishin chizu, 146; Sangawa, Jishin no Nihonshi, 171–172; Usami, Higai jishin, 148–151; and “Wakisaka Antaku nikki” and “Ōsaka jishinki,” in DNJS, vol. 2 (otsu), 330–333, 340–344.
-  Tsuji, “Ansei tōkai, nankai jishin,” in Chūō bōsai kaigi, 1854 Ansei tōkai jishin, Ansei nankai jishin hōkokusho, 2. See also Nishiyama Shōjin, “Ansei nankai jishin ni okeru Ōsaka de no shinsai taiō,” in Chūō bōsai kaigi, 1854 Ansei tōkai jishin, 51, 55–59, 62.