著者

Uyeshima Makoto Kinoshita Masataka Iino Hideaki Uyeda Seiya

出版者

東京大学地震研究所

雑誌

東京大學地震研究所彙報 = Bulletin of the Earthquake Research Institute, University of Tokyo (ISSN:00408972)

巻号頁・発行日

vol.64, no.4, pp.487-515, 1990-03-30

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The VAN-method for short-term earthquake prediction based on monitoring telluric potential changes, which has reportedly been successful in Greece, is now under testing in Japan. More than 20 local networks have been established and tested for about one year using existing electrodes and cables of the Nippon Telegraph and Telephone Corporation (NTT). Generally the records suffer from cultural noise much higher than in Greece, but some stations far from DC-powered rail-roads were found to be reasonably noise-free. Preliminary examination of data indicates that potential precursory signals in the sense of the VAN-method were recognized preceding earthquakes of M≧5 at some stations. This report presents an example, i.e. the possible correspondence between a specific type of telluric potential change appearing in the channel 2 at Teshikaga station, Hokkaido, and seismicity in the region off Kushiro, Hokkaido.

著者

Uyeda Seiya Watanabe Teruhiko Ozasayama Yoji Ibaragi K.

出版者

東京大学地震研究所

雑誌

東京大学地震研究所彙報 (ISSN:00408972)

巻号頁・発行日

vol.55, no.1, pp.55-74, 1980-08-25

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Results of terrestrial heat flow measurements in Peru and Ecuador conducted in 1969, are reported. Eight different sites in Peru and one site in Ecuador were visited for underground temperature measurement. However, data from only five metal mines in Peru and the metal exploration site in Ecuador were usable. The geothermal gradient data on four oil fields in Peru and two in Ecuador were referenced. Although high heat flow has been indicated on the continent side of the Andes (the Gasapalca and the Guajone mines and the Ucayali oil field), low geothermal gradients were also found in mines in high Andes (the Raura and Cerro Verde mines). The latter are suspected to be the result of ground water circulation. The highly disturbed cases of the Morococha and San Vicente mines showed almost zero gradient. Much more work is needed to delineate the regional heat flow pattern of the area.

著者

Uyeda Seiya Horai Ki-iti

出版者

東京大学地震研究所

雑誌

東京大学地震研究所彙報 (ISSN:00408972)

巻号頁・発行日

vol.41, no.1, pp.83-107, 1963-06-30

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Eight sets of new data on the terrestrial heat flow have been added to the existing five sets of data in Kanto and Chubu Districts, or the central part of Japan. Of the eight new localities, seven are in metal mines and one in a natural gas field. Expressing the geothermal gradient ΔT/ΔZ in ℃/100 m, and the heat flow in 10-6 cal/cm2 sec, the present data can be summarized as: Mobara: ΔT/ΔZ=1.85, Q=0.54 Ashio: ΔT/ΔZ=3.57, Q=2.23 Chichibu: ΔT/ΔZ=1.90, Q=1.34 Kamioka: ΔT/ΔZ=2.77, Q=1.80 Nakatatsu: ΔT/ΔZ=2.90, Q=1.95 Kune: ΔT/ΔZ=1.97, Q=1.60 (Honzan) ΔT/ΔZ=2.17, Q=1.44 (Nako) Minenosawa: ΔT/ΔZ=2.82, Q=1-79 Combined with previous data, the above figures indicate the following facts: a) Heat flow on the Pacific coast side of Kanto District is, without exception, small (Q<1.00); b) High heat flow region, known on the Japan Sea coast side of Tohoku District (Q>2.00) extends to the north-western part of Kanto District and possibly down to the Izu-Mariana Arc. This high heat flow region apparently coincides with that of Tertiary volcanism of Japan, c) Heat flow in Chubu District is higher than the world's average (Q = 1.2~1.4) but not very much. This high value may be accounted for by the relatively thick crust of the District.1.1957年以来,地震研究所においては,日本全土における地殼熱流量分布の決定が試みられてきた.1961年以降には,日本鉱業協会,日本石炭協会,天然ガス鉱業会,帝国石油株式分社,東京大学地質学教室の渡辺武男教授,久野久教授他の大きな御協力を得て,全国の鉱山,炭礦,油田,ガス田等においてやや組織的な地熱測量が行なわれた.地球熱学第8報乃至第12報は,その結果の報告である,この仕事では,樋口重雄氏,山川一郎氏(日本鉱業協会),佐久洋氏,佐野孝一氏(石炭協会),橋爪義雄氏(天然ガス鉱業会),柴宮博氏(帝国石油株式会社),他多くの方々,並びに,各現場での数多の方々の御指導,御援助を得た.記して深甚の謝意を表明する.岩石熱伝度測定のための試料研磨にっいては,地震研究所渡辺佐技官に多大のお世話になつた.なお,この研究は地震研究所力武常次教授の全面的御援助の下に終始したものである.従来,関東地方,中部地方には,信頼し得る地殼熱流量,Q,の測定は5個であつた.すなわち,Qを10-6cal/cm2 secで表して,日立(Q=0.94~1.21),鹿島(Q=0.76),勝田(Q=0.91),東京大学構内(Q=0.74),笹子トンネル(Q=2.06),である.今回は,新たに,8個の測定が加えられた,その結果概要は以下の通りである.千葉県茂原: Q=0.54栃木県足尾: Q=2.23埼玉県秩父: Q=1.34岐阜県神岡: Q=1.80福井県中竜: Q=1.95静岡県久根: Q=1.60,(久根坑)Q=1.44,(名合坑)静岡県峰之沢: Q=1.79本文,第1図を参照しつつ,上記結果を検討すると,以下のことが明らかである.a)関東地方太平洋側では,地殻熱流量は例外なく小さい(Q<1.0).b)従来察知されていた,東北地方日本海側の地殻熱流量の大きい地域(Q>2.0)の延長が,関東地方西北部にもみられ,所謂,第三紀火成活動帯と一致している.この地域は,更に南にのび,伊豆マリアナ弧につながる可能性がある.c)中部地方の大部分は,世界的平均熱流量(Q=1.2~1.4)よりは大きい値を示すが,Q=2.0には至らない程度である.なお,この地方では,既報,草津白根地熱地帯での結果のごとく,熱流量が局地的異常を示した例もあるが,伊豆大島火山,丹那盆地,清越鉱山等,おそらくは地下水の流動のために,信頼するに足る地温勾配の得られない場合もあつた.各測点での記録は以下のごとくである.

著者

Uyeda Seiya Kumamoto Atsumi

出版者

日本学士院

雑誌

Proceedings of the Japan Academy. Ser. B: Physical and Biological Sciences (ISSN:03862208)

巻号頁・発行日

vol.80, no.3, pp.140-147, 2004

被引用文献数

4

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Kushida and Kushida found that FM radio waves from stations at distances over-the-horizon are received before earthquakes. Based on this finding, since the mid-1990's, the Kushidas have been practicing "Earthquake Precursor Detection Experiment". The performance of the Kushida method during 2000-2003 has been evaluated by checking their predictions against the actual seismicity. During the period, there were 92 Kushida predictions mentioning the possibility of M &ge; 5.5 event, whereas there were 49 M &ge; 5.5 earthquakes in the Japanese region. If the criteria for successful prediction are set as: the errors in date is less than one day, epicentral position is roughly within specified area, and error in M is less than 0.5, the success rate was 20% and the alarm rate was 12%. If we relax the criteria to: the errors in dates within 10 days, epicenter within additional 100 km of specified area and the magnitude error less than 1.0, the success rate was 40% and the alarm rate was 27%. These rates may look insufficient for a practical prediction method. Considering, however, the fact that no other short-term prediction has ever been made in Japan so far it is a significant achievement. Moreover, it was found that in almost all failed predictions, meaningful signals were detected although the interpretations were incorrect. This indicates that the method is promising provided further investigation is carried out. The same evaluation at the M &ge; 6.0 level showed that the general performance was similar to the M &ge; 5.5 level, except that both success rate and alarm rate were lower at the M &ge; 6.0 level. If this unexpected finding is real, it might be inherent to the methodology using scattering of short-wave length radio waves as suggested by M. Hayakawa and may contain important information in understanding the earthquake physics and LAI-coupling. The results of the present study indicate strongly that the earthquake prediction research using anomalous transmission of VHF FM radio waves should be enhanced in parallel with complementary research in other frequency ranges.<br> <br> <br> (Contributed by Seiya UYEDA, M.J.A.)<br>