When fire is spreading over a city, to evacuate safety what can be the minimum distance to start evacuation? The purpose of this paper is concerned to analysis of this kind of human behavior while contributing to the improvement of Evacuation guide Technique and developing a parameter of Evacuation behavior Simulation. For this study two cases were taken; 1) Sakata Fire (in 1976): as an example of one source fire. 2) Kanto Earthquake (in 1923): as an example of multi-source fire. Among these two examples the latter’s distance (distance from front to residents) is longer.

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　三浦半島南端の毘沙門湾付近は，1923 年と1703 年のの時にそれぞれ約1.2m隆起し，地震間では約 3.7 mm/年の速度で沈降している．最近，半島南西部の小網代湾の堆積物調査から1703年の一つ前の地震の履歴が1060年～1400年の間と推定した[Shimazaki et al., 2011]．本研究は，三番目のの発生履歴について，さらに詳細な情報を提示し，その上で地殻変動の蓄積と地震の発生間隔との関係について考察する．　毘沙門湾に注ぐ4つの谷のうち東側の谷底では，高さ1～2mの低崖で画された海成段丘が5段認められ，間欠的に発生するに対応する可能性が指摘されている[地理院，1981]．最低位の段丘面は標高+2.1mに分布し，海岸沿いに西側の谷まで発達している．本研究は，この最低位の段丘面をさらに細分して形成過程を検討する．

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Seismograms from the 1923 Kanto earthquake (M=7.9) and its aftershocks at the Yamagata observatory of JMA (The Japan Meteorological Agency) in Tohoku district, Japan, are examined. They were recorded by the Imamura-type strong motion seismograph. Horizontal-component records from the main shock and the 1924 Tanzawa earthquake (M=7.3), one of the largest aftershocks, are digitized and the instrumental characteristics of the seismographs are examined. Natural period T_o and damping ratio v of the instrument are evaluated to be 4.5s and 1.5 for both the NS and EW components from the free oscillation records and documents for the results of testing the instrumental response. The maximum displacement in EW component of 11.2cm is obtained for the main shock in the period range from 2 to 20s, after the instrument correction.
On the other hand, uncertainties of the instrumental characteristics remain for the seismograms from the 1923 Kanto earthquake observed at the Mukaiyama observatory of the Tohoku Imperial University in Sendai, [TAKEMURA et al. (1995)]. The Sendai city is located about 40km east from the Yamagata city. The epicentral distance and azimuth of the Mukaiyama observatory is not so different from those of the Yamagata observatory for the 1923 Kanto earthquake. It is found that the displacement records at Sendai and Yamagata have mostly the same amplitude for the recent moderately large earthquakes with almost the same location of epicenter as the 1923 Kanto earthquake. All the records were observed by the strong motion displacement seismographs of T_o=6s and v=8 both at the Yamagata observatory and at the Sendai district meteorological observatory of JMA. This fact indicates that the displacement at the Mukaiyama observatory in Sendai ought to show almost the same amplitude as one at the Yamagata observatory during the 1923 Kanto earthquake. Then, we redetermined T_o of the instrument at Mukaiyama observatory so that the amplitude of the displacement after the instrument correction is the same as that at the Yamagata observatory. Redetermined T_o is 5s in EW component, being meaningfully longer than the results estimated by TAKEMURA et al. (1995).

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The 1923 Kanto earthquake (M=7.9) is one of the most destructive events in Japan. Many studies on seismology and earthquake engineering have been carried out for this earthquake. In one and half decade from 1990, investigations of its source process and strong ground motions had been especially advanced. This paper reviewed the results of the studies in this period. Records from Ewing seismoscope and Imamura seismograph at Hongo were restored and simulated to presume the long-period strong ground motion in Tokyo during the main shock. Other seismograms involving Imamura seismograph records which completely recorded ground motions from main shock and aftershocks at several stations were also revealed in this period. These seismograms were useful for elucidating the source process of the main shock having two big sub-events, whose locations were about 40 km distant on the fault plane, which occurred with time interval of 10 to 15 s after the initial small rupture duration of 3 to 5 s. This complex faulting process of the main shock caused the regional variations of strong ground motions in the near source region, which were estimated from the descriptions of personal experiences. The aftershock sequence was also clarified from these seismograms. Two M=7 class aftershocks were newly found to have occurred at 3 and 4.5 minutes after the main shock, so that total number of aftershocks with more than M=7 was six for the Kanto earthquake. The number of big aftershocks of the Kanto earthquake is meaningfully larger than the other M=8 class subduction events. The seismic intensity on the JMA scale due to the second shaking caused by the first big aftershock was also estimated to be 6 in Tokyo metropolitan area, though the analysis of the descriptions of personal experiences, which was almost the same as the first shaking by the main shock. Besides above studies, the precise seismic intensity distribution of the Kanto earthquake was obtained in this period, after raveling out many confused damage statistics data.

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96 photographs of seismograms from the 1923 Kanto earthquake (M=7.9) have been preserved at JMA (the Japan Meteorological Agency). These seismograms were obtained at meteorological observatories in and around Japan and Tohoku Imperial University in Sendai, whose epicentral distances are within about 2000km. P-wave forms of the main shock are recorded at 37 observation stations, though larger shaking parts of the ground motions are saturated on the records at almost all the stations. First, a type of seismograph and its instrumental characteristics are examined for each record from old materials and old records preserved at JMA. It is found that the seismograms at 29 stations were recorded by Portable Seismographs with natural period T of about 5sec and magnification V of 10 to 100, and most of the others by Omori's Seismographs with T of 10 to 30sec and V of 10 to 20 and by Wiechert Seismographs with T of about 5sec and V of about 100. Secondly, P-wave characteristics of each record are examined. We reexamined polarities of initial P-wave motions and reviewed focal mechanisms obtained for the Kanto earthquake. We also found that P-wave forms at many stations have some characteristics in common. The P-waves begin with small amplitude and the first remarkable phase with a large amplitude appears after the duration of the initial small phases. The second remarkable phase is also identified several seconds after the first remarkable phase, irrespective of the epicentral distances of the stations. The duration time τ₀₁ of the initial small amplitudes correlates with the epicentral distance at each station. It can be explained by the difference of calculated arrival times between Pn and Pg phases or between Pn and P* phases in addition to a duration of the initial small rupture near the hypocenter. The duration of the initial small rupture is evaluated about 4.5sec from τ₀₁'s at observation stations within the epicentral distance of 170km. In the meantime, the difference τ₁₂ of arrival times between the first and the second remarkable phases correlates with the azimuth angle of each station from the epicenter. Geometry and difference of occurrence times of big subevents are evaluated on the fault plane of the main shock from the data of τ₁₂'s, if we assume the two remarkable phases are due to two big subevents, respectively. The second subevent is located about 40km distant from the first subevent in the direction of about N 100°E, and the time interval of the occurrences of the two subevents is about 14sec.

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Records observed at the Takada observatory by an Imamura's type strong motion seismograph are useful in Japan to investigate a source process of the 1923 Kanto earthquake (M=7.9). Ground motion in the vertical component is completely recorded to the end. Those in horizontal components are also recorded to the end, though the amplitudes of them are saturated in the midst of the records. The instrumental response of the seismograph has been already clarified by TAKEMURA and NOZAWA (1996), and many records from the recent earthquakes occurring near the focal region of the Kanto earthquake are also obtained at the same site with modern instruments. First, a crustal structure model from the source to the station is established so as to explain the dispersion characteristics of Love-waves observed for the recent earthquakes, and their records are simulated by the normal mode theory using the obtained structure to confirm its validity. Secondly, the records from the Kanto earthquake are reproduced using the same structure model. NOZAWA et al. (1995) proposed the two possible source models for the Kanto earthquake through the simulation of the records at the Gifu observatory. Two big subevents with a time interval of about 12s are assumed on the fault plane in both the models, while the focal mechanism and the focal depth of the second subevent are different between these models. It is found that these models similarly explain the records at the Takada observatory from the Kanto earthquake. The maximum displacements of the reproduced horizontal ground motions are estimated about 20cm in NS component. and about 10cm in EW component. These results are consistent with the fact that the amplitudes of the records in NS component are strongly saturated compared with those in EW component.

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