28/10/1707 : Séisme de Houei (宝永地震)
(Source : Wikipedia Commons)
D’une magnitude de 8, 4 à son épicentre, 6,0 à Osaka, c’est un des plus importants séismes connus à avoir ébranlé le Japon. Il a peut-être provoqué la dernière éruption du Mont Fuji 49 jours plus tard.
A Osaka, 560 personnes sont mortes à cause du séisme, 7.000 à cause du tsunami qui l’a suivi. A Osaka, les vagues ont atteint 3 m de hauteur. Suite à ce tsunami en particulier, les habitants de la région ont construit des abris d’urgence et se sont organisés pour se protéger en cas de tremblement de terre d’un tsunami éventuel, comme l’écrit Smits :
The Case of Osaka
Before taking a closer look at the Tōhoku situation, the case of Osaka provides useful comparison. Two massive tsunamigenic earthquakes shook Osaka and large areas along the coast in 1707 and 1854. Until March 11, 2011, many historical seismologists regarded the 1707 Hōei Earthquake as the most powerful known earthquake to have shaken Japan. It generated tsunami waves that washed through the coast of Honshū from Suruga Bay southward, through much of Shikoku, and parts of northern Kyūshū. Like Hōei, the December 24, 1854 Ansei Nankai Earthquake (M8.4 ) was an offshore subduction zone earthquake that generated a destructive tsunami. Both the Hōei and Ansei Nankai earthquakes were geologically similar to the 2011 Tōhoku Earthquake.
The Hōei Earthquake and tsunami caused coastal villages to develop evacuation plans that usually involved the entire community assembling at a temple, shrine, or other suitable location on high ground. Anticipating the need occasionally to spend a night or two at such locations, some villages constructed simple shelters at the evacuation area. Throughout the area within range of the 1707 tsunami, generations of rural coastal residents fled to high ground when the earth shook. Sometimes the move proved unnecessary, but the Hōei devastation loomed large in historical memory. A writer living in the Kii Peninsula, for example, explained that “fearing a tsunami, people set up lean-to shelters in the mountains,” and letters, diary entries, and other documents dealing with rural areas regularly describe lowland villages in terms such as “Owing to tsunamis, everyone had set up huts in the mountains, and not a single person was dwelling” in the lowland village.19 Not all accounts, however speak of an effective response. “There is a saying that complacency is the greatest enemy (yudan-taiteki),” began a short essay that went on to criticize people of the present for ignoring the lessons of the 1707 Hōei Earthquake and tsunami “as if it were an ancient tale” and not currently relevant knowledge.20 The writer was referring to Osaka.
19 “Zoku jishin zassan,” in Shinsai yobō chōsakai, Dai-Nihon jishin shiryō, pp. 420, 423. For more examples of villagers fleeing to high ground in advance of tsunamis, see, pp. 419, 462, 467, 469-471, 482-483.
20 “Jishin nikki,” in Shinsai yobō chōsakai, Dai-Nihon jishin shiryō, vol. 2 (otsu), p. 488.
Voir aussi A. Nishiyama, People’s Reaction at Osaka on Disaster from Houei Earthquake occured in 1707, 歴史地震 第 18 号（2002） 60-72 頁 (en japonais uniquement; pas d’illustration)
 http://ja.wikipedia.org/wiki/%E5%AE%9D%E6%B0%B8%E5%9C%B0%E9%9C%87; Hōei earthquake: http://en.wikipedia.org/wiki/1707_H%C5%8Dei_earthquake