The Ansei Edo Earthquake
One of the many accounts of the Ansei Edo earthquake was Record of the Great Earthquake and Great Storm (Ōjishin ōkaze kenmonki). Its title refers to the typhoon that struck Edo approximately ten months after the earthquake, so this account reflects approximately a year of hindsight. The “General Notes” section starts with a concise summary of the earthquake: “First, there was the great Kantō [Genroku] earthquake on the twentysecond day, eleventh month of Genroku 16, with a great fire on the twentyninth day. Now, because it has been 154 years between then and Ansei 2, the passing of years lulled people into thinking that Edo was a city without major earthquakes. Therefore, the population was unprepared for a great earthquake. Thinking that Edo was prone only to fires, people built plaster-walled dwellings and erected plaster-walled enclosures with tile roofing. Such construction became the major cause of injuries.” Moreover, the destruction wrought by the earthquake was uneven: “In this situation, the visible effects of the earthquake were severe in some places and weak in others. Thatched-roof structures generally suffered little damage, whereas the walls of earthen storehouses collapsed right and left, causing countless deaths from debris striking the men and women who emerged to flee. The collapse of compound walls of mansions, stone walls, objects thrown off from such structures, falling stone lanterns, and so forth harmed many people.” One important aspect of the Ansei Edo earthquake was that its impact varied widely as a function of topography, underlying geology, construction materials, and social geography.
The Ansei Edo earthquake defies simple characterization. This chapter presents a description of the patterns of destruction, benefit, relief, and rebuilding that occurred in connection with this event. In this context, I argue that the earthquake was both a destructive and a creative event whose effects differed owing to the interplay of local geology and social geography. Moreover, conclusions about this earthquake in the limited English-language literature, especially with respect to patterns of destruction, are incomplete and misleading. Rumors and exaggerations about the earthquake were common both during its immediate aftermath and throughout the next century. An understanding of what actually took place on the second day of the tenth lunar month, 1855, and in the months thereafter, is a prerequisite for understanding the earthquake's broader significance, which is discussed in subsequent chapters.
Patterns of Death and Destruction
The overall death toll, civilian and military, amounted to about 1 percent of Edo's population. Fires were a problem for the first two to three days, usually in areas experiencing the most severe shaking. Winds were calm, however, and most deaths occurred because of falling objects and crushing forces. This situation contrasts sharply with the Great Kantō Earthquake of 1923, in which fire was the main cause of death. In 1855, several factors promoted perceptions of exaggerated death tolls, and rumors circulated of one hundred thousand or more killed.
Aftershocks kept the residents of Edo on edge. Astute observer Mishima Masayuki recorded aftershocks in detail in After the Shaking (Nai no nochimigusa). He recorded at least one aftershock for almost every day of the tenth month. Aftershocks continued into the first few days of the eleventh month, but by then their frequency had greatly diminished. The unease prompted by these aftershocks caused many townspeople initially to abandon their houses and dwell in hastily erected huts by the roadside. “People erected various huts and for a while endured rain and mist.” Moreover, “There were also many residents of areas near the shore on land reclaimed from the sea in Fukagawa who fled because of fears that a tsunami might arrive,” a point made in several accounts. These temporary dwellings had become a problem in some areas to the extent that three days after the earthquake, the City Magistrate's Office (Machibugyō, hereafter “City Magistrate”) declared, “There are so many temporary huts erected by those fearing aftershocks that military personnel cannot pass through. City officials must rectify this situation.” Ansei Record (Ansei kenmonroku) compared the 1830 Kyoto earthquake to the current event: “The current earthquake has a lower frequency [of aftershocks] than Kyoto did, and their intensity is not as severe. Similar to the situation reported in Thoughts on Earthquakes [Jishinkō], however, many people became frightened and slept in the main streets. Therefore, an anonymous person posted a notice at Nihonbashi that read, 'There is no reason [ri] that another earthquake will occur, so set your minds at ease and return home. If not, the night air will eventually make you ill.'” Accumulated knowledge from recent past earthquakes undoubtedly shortened the time required for many of Edo's residents to realize that the worst was behind them and to shift into rebuilding and recovery mode.
-  “Ōjishin ōkaze kenmonroku,” in NJS, vol. 5, supplement 2, part 1, 533.
-  “Nai no nochimigusa,” in DNJS, vol. 2 (otsu), 579–580.
-  “Jifūroku,” in DNJS, vol. 2 (otsu), 538. See also “Ansei itsubō jishin kibun,” in NJS, vol. 5, supplement 2, part 1, 446.
-  Chūō bōsai kaigi, eds., 1855 Ansei Edo jishin hōkokusho (Fuji sōgō kenkyūsho, 2004), 77.
-  AKR, vol. 3, 10 (ge no jū). See also Arakawa Hidetoshi, ed., Jitsuroku, Ō-Edo kaimetsu no hi: Ansei kenmonroku, Ansei kenmonshi, Ansei fūbunshū (Kyōikusha, 1982), 85–86.