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Research paper : A study of paleoearthquakes at archeological sites (A. Sangawa)−90−Synthesiology - English edition Vol.2 No.2 (2009) gravel, but large pebbles are left behind when sand and gravel rise with the underground water. In this case, looking only at the surface, it seems that liquefaction occurred in the sand layer without gravel, but that is not the actual case. Basic knowledge can be obtained by sequential observation of the flow in the layer when liquefaction occurs up to the arrival of the sand boil to the surface.6 The Great Hanshin Awaji EarthquakeThe Hanshin Awaji Earthquake of January 17, 1995 was caused by the activity of the Nojima Fault shown in the “Akashi” section of 1:50,000 Geological Map published in 1990 by the Geological Survey of Japan[18]. The position and the movement of this fault was correctly described in the map manual, but at the time of its writing, the information was not at the level that allowed predictions of the scale of earthquake damages to be caused by future activities of the faults.After the Hanshin Awaji Earthquake, the importance of active faults was recognized, and the Headquarter for Earthquake Studies Promotion was established in the Agency for Science and Technology (current Ministry of Education, Culture, Sports, Science and Technology). The national project was started to study the accurate positions and activities of major active faults throughout Japan, to predict statistically the future fault activities by investigating the history of their activities, and to project the scale and spread of the seismic movement caused by their activities. The survey was conducted as joint efforts of the Geological Survey of Japan, Agency of Science and Technology, as well as the local governments and universities throughout Japan.Many active faults stretch from the southwestern area of the Kyoto Basin, passing by the north rim of the Osaka Plain, and traveling all the way to Awajishima. The Hanshin Awaji Earthquake was caused mainly by the movement of the Nojima Fault (labeled NF in Fig. 6). Immediately after the earthquake, there was worry that a larger earthquake may occur in the near future in connection with this earthquake if there were other faults that were inactive for long periods and their energy was being accumulated. Many people living in the northern part of Osaka Plain became worried.However, traces of the Keicho Fushimi Earthquake in 1596 were found from many archaeological sites in the Keihanshin and Awaji regions (Fig. 6), and based on these evidences, the active faults in question were active in the earthquake 399 years ago. Moreover, in the trench survey of active faults conducted by the Geological Survey in 1995, it was found that many faults in the north rim of the Osaka Plain to the east coast of Awajishima, such as Arima-Takatsuki Fault Zone (labeled AFZ in Fig. 6) were active in the Keicho Fushimi Earthquake[19]. Together with the result of the trench survey that the activity of the Arima-Takatsuki Fault Zone prior to this occurred about 3,000 years ago[19], people were relieved of their worry that “a giant earthquake capable of annihilating the Keihanshin region will follow the Hanshin Awaji Earthquake.”On the other hand, many cultural properties such as Buddhist sculptures were damaged when the temples and shrines collapsed, as well as the archaeological artifacts that were on display during the Hanshin Awaji Earthquake. Demands were raised for measures against earthquakes for cultural properties and for support activities after the earthquake in the fields of history and archaeology.Although swift recovery measures were needed in the Hanshin and Awaji regions that were hardest hit by the disaster, the construction work for recovery destroyed buried cultural properties, and the number of excavation surveys of archaeological sites increased sharply. As emergency measures, many archaeologists of the local governments throughout Japan were dispatched to the Hyogo Prefecture to support the excavations, and joined the survey with local archaeologists[20].The archaeologists dispatched from around Japan had first-hand observation of the earthquake damages, and learned the basic knowledge of earthquakes. Moreover, in the process of excavating the sites of the Hanshin Awaji regions, many traces of the Keicho Fushimi Earthquake were discovered[21], and people who were unfamiliar with earthquake traces were able to learn the basic survey methods.With the increased interests in earthquake traces, the archaeologists of Japan took part to edit and publish the Excavated Traces of Earthquake, a catalog of earthquake traces[22]. The journal Kodaigaku Kenkyu started a section for collecting earthquake traces in each issue, and this continues to the present[17][23].In the aforementioned 1:500,000 Neotectonic Map series, the “Kyoto” region which became the center of attention in the Hanshin Awaji Earthquake was revised totally, and the second edition was published. In the “Paleoearthquake Data Map,” the traces of Keicho Fushimi Earthquake and the mega-earthquakes from the Nankai Trough are shown in different colors to indicate the corresponding earthquakes[24].7 In preparation for the earthquakes in the 21st centuryImmediately after the Hanshin Awaji Earthquake, I spoke with many people of the disaster regions, and was shocked to find that most people had believed, “There will be no earthquake in the Kansai area.” In reality, there are many active faults in this area, and great disaster befell in the Keicho Fushimi Earthquake about 400 years ago. At the same

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