Compilation of Eleven New Heat Flow Measurements on the Japanese Islands

New land heat flow data at eleven localities in Japan are presented. There are four localities in the Tohoku District, one in the Kanto District, three in the Shikoku District, one in the Chugoku District and two. in the Kyushu District. The obtained heat flow values, varying from 1.28 HFU (1HFU=1O-6 cal/cm2 sec) to 21.6 HFU, (i.e. from 53.5 to 905mW/m2), are in general agreement with the previously estimated heat flow distribution in the area.日本での未発表の陸上地殻熱流量の値をまとめて報告する.測定地点は東北地方に4地点,関東地方に1地点,四国地方に3地点,中国地方に1地点,九州地方に2地点の合計11地点である.地殻熱流量の値は1.28HFU(1HFU=10-6 cal/cm2 sec)から21.6HFUまで(53.6mW/m2から905mW/m2まで)変化しているが,これまでに得られた地殻熱流量分布の傾向とほぼ一致している

Single-channel Seismic Profiling at Koaidame in Tokyo

Koaidame, a water area generally without artificial modifications, in Mizumoto Park in Tokyo was surveyed using a high-resolution single-channel seismic profiler. Koaidame was constructed for irrigation use in 1729 in an old river channel. Bottom sedimentary structures are revealed to search for any traces of paleoearthquakes such as fault displacement, co-seismic gravity slumping, liquefaction, and tsunami deposits. No evidence is recognized within the structure

Resurvey of Possible Seismic Fissures in the Old-Edo River in Tokyo

Geo-slicer sampling of riverbed strata, boring sampling of riverside strata, single-channel seismic reflection survey, and electric survey were carried out to understand the causes of ground fissures and ruptures with a vertical dislocation of 25cm found by Shimazaki and others beneath the Old-Edo River in Tokyo in 1997. We concluded that fissures and ruptures were caused by gravity slumping due to liquefaction taking place near a paleo-valley, which was found by the reflection survey to run across the Old-Edo River. In the 1997 survey, at least two liquefaction and slumping events, probably corresponding to two large earthquakes, were identified from a Geoslicer sample down to about 8m in depth. Their ages were reported as after 1800yBP and 2900－3700yBP, respectively. Dating results for new samples obtained in this study are consistent with previous estimates

36. Microfilming of Historical Seismograms at the Earthquake Research Institute, University of Tokyo(Preliminary Report)

地震研究所資料室には,19世紀末の地震観測初期の時代の地震記象をはじめとして,歴史地震記象(世界標準地震観測網整備以前の記象)が約25万枚保存されている.1982年に地震研究所で開催されたアジア・オセアニア地域歴史地震記象ワークショップを機に,地震研究所における歴史地震記象のマイクロフィルム化が行なわれた.フィルム化には,時間順に全ての記録をフィルム化(日別記象フィルム化)する場合と,主な地震記象のフィルム化(地震別記象フィルム化)を行なう場合とがある.4つの代表的な地震計(大森式水平動地震計耐震家屋甲号および同乙号,土中家屋Gray-Ewing上下動地震計,ならびに耐震家屋上下動地震計)については,1899-1942年の期間に対して,日別記象フィルム化を行った.また,マグニチュード7以上の地震の記象と,記録振幅が100mmを越える記象とについて,上記4地震計を含む8地震計の記象を全期間にわたって,地震別に記象フィルム化した.35mmカメラにより,合計38,143枚の地震記象が126本のロールに撮影された.全フィルムの複写コピー1セットは国際データ交換に役立つよう,世界データセンターAに寄贈されている.The Seismogram Archive of the Earthquake Research Institute contains about 250,000 pre-WWSSN seismograms, including old seismograms from the late 19th century. In response to the resolutions passed at the Tokyo Workshop on Historical Seismograms in 1982, the initial phase of filming the historical seismograms at ERI started in early 1983. The initial phase contains two different filming procedures : daily record filming and event record filming. The daily record films were made by microfilming all the smoked paper records from four representative seismographs operated in Tokyo from 1899 to 1942. The four seismographs chosen are OMORI-1(EW component, T0=60sec, magnification=15), OMORI-2(NS, 60sec, 20), VERTICAL-1(UD, 20sec, 10), and EWING(UD, 7sec, 20). For the event record filming, seismograms which contain large events (magnitude larger than 7) or contain traces with the maximum amplitude larger than 100 mm are chosen from eight representative seismographs, including the above four. A total of 38,143 seismograms were filmed with a 35mm camera on 126 reels of microfilm. One duplicate set of films was sent to the World Data Center-A for international data exchange