著者

宇津 徳治

出版者

公益社団法人 日本地震学会

雑誌

地震 第2輯 (ISSN:00371114)

巻号頁・発行日

vol.30, no.2, pp.179-185, 1977-08-05 (Released:2010-03-11)

被引用文献数

7 14

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Two kinds of probabilities p1 and p2 are considered in connection with the earthquake prediction, p1 is the probability that a prediction will be successful, and p2 is the probability that an earthquake will be predicted. Both “prediction” and “earthquake” have been defined by some criteria X and Y, respectively. The status of the prediction based on each observational element can be indicated by a point on the p1-p2 plane. The effectiveness of the prediction is related to p1 and p2 by an equation in the form E=p2(a-b/p1)-c where a, b and c are constants. If two or more observational elements are considered, p1 and p2 for the combined elements are calculated from p1 and p2 for each element under some assumptions. Formulas for such calculation have been derived. In these formulas the probability p0 that a random prediction (under criterion Y) will be successful plays an important role. For example, if a prediction is done when precursorlike anomalous phenomena are observed for two independent elements A and B, the probability of successful prediction is given by p1(A ∩ B)=1/1+(1/Ap1-1)(1/Bp1-1)/(1/p0-1) where Ap1 or Bp1 is the p1-value for element A or B alone. The effectiveness of the multielement prediction is discussed by using these formulas.

著者

宇津 徳治

出版者

公益社団法人 日本地震学会

雑誌

地震 第2輯 (ISSN:00371114)

巻号頁・発行日

vol.28, no.3, pp.303-311, 1975-10-10 (Released:2010-03-11)

参考文献数

13

被引用文献数

4 4

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A correlation has been found between intermediate earthquakes in Hida (the region around the city of Takayama) and shallower earthquakes in central Kwanto (the region around the city of Tokyo). Among 61 earthquakes of M≥5.5 in central Kwanto during the 51 years from 1924 through 1974, 37 earthquakes occurred in the one-year periods centered by the times of 16 earthquakes of M≥5.0 in Hida. The probability that 37 or more earthquakes in central Kwanto occur during those periods (total length=14.46 years) is 1.5×10-7, if the Kwanto earthquakes are distributed randomly in time. It seems impossible that the smallness of this probability is wholly attributed to some effects other than the true correlation, such as the selection of data, the clustering of earthquakes, etc. The correlation suggests the mechanical connection between the two seismic regions, which belong to the same segment of the Pacific plate underthrusting at the northeastern Japan arc.

著者

宇津 徳治 関 彰

出版者

公益社団法人 日本地震学会

雑誌

地震 第2輯 (ISSN:00371114)

巻号頁・発行日

vol.7, no.4, pp.233-240, 1955-03-30 (Released:2010-03-11)

参考文献数

28

被引用文献数

6 33

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The after-shock regions of 39 shallow earthquakes which took place in and near Japan (Table 1) are determined and the relation between thier areas and the magnitudes or energies of main-shocks is investigated. If we assume that the logarithm of the area A (km2) and the magnitude M are in linear relation, i. e., logA=aM+b (Fig. 2-3), the constants a and b become as follows, a=1.02±0.08, b=-4.01±0.57 (for 39 total earthquakes)a=0.93±0.08, b=-3.18±0.61 (for 23 oceanic earthuakes)a=0.85±0.10, b=-3.05±0.72. (for 16 land earthquakes)From the relation between M and E (erg), we get A∝Em, where m≈1/2, then E/A∝A∝√E, this means that the surface density of energy increases as the energy increases.

著者

宇津 徳治

出版者

北海道大学理学部地球物理学教室

雑誌

北海道大学地球物理学研究報告 (ISSN:04393503)

巻号頁・発行日

vol.22, pp.73-93, 1969-08-30

著者

宇津 徳治

出版者

公益社団法人 日本地震学会

雑誌

地震 第2輯 (ISSN:00371114)

巻号頁・発行日

vol.32, no.4, pp.495-497, 1979-12-25 (Released:2010-03-11)

参考文献数

5

著者

宇津 徳治

出版者

公益社団法人 日本地震学会

雑誌

地震 第2輯 (ISSN:00371114)

巻号頁・発行日

vol.41, no.4, pp.613-614, 1988-12-25 (Released:2010-03-11)

参考文献数

5

被引用文献数

1

著者

宇津 徳治

出版者

公益社団法人 日本地震学会

雑誌

地震 第2輯 (ISSN:00371114)

巻号頁・発行日

vol.24, no.4, pp.369-371, 1972-01-31 (Released:2010-03-11)

参考文献数

2

著者

宇津 徳治

出版者

公益社団法人 日本地震学会

雑誌

地震 第2輯 (ISSN:00371114)

巻号頁・発行日

vol.19, no.3, pp.226-227, 1966-12-25 (Released:2010-03-11)

参考文献数

2

被引用文献数

1

著者

宇津 徳治

出版者

北海道大学理学部地球物理学教室

雑誌

北海道大学地球物理学研究報告 (ISSN:04393503)

巻号頁・発行日

no.21, pp.45-52, 1969-02

著者

宇津 徳治

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.54, no.2, pp.253-308, 1979-12-25

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Only one catalog has been available for moderate to large earthquakes occurring in the region of Japan in the years 1885 to 1925. However, this catalog, published by the Central Meteorological Observatory in 1952, has often been criticized as misleading, because no con- sideration is given to the depth of focus and magnitude values are unreasonably large for many earthquakes. A new catalog of earthquakes of M≧6 is prepared in this study to meet the demand in earthquake prediction and earthquake risk studies in Japan. Both instrumental and macroseismic data are used in the determination of focal parameters. Most of the data are taken from either published reports of the Central Meteorological Observatory, the Imperial Earthquake Investigation Committee, or written station reports collected and stored by the Japan Meteorological Agency and the University of Tokyo. The hypocenter location is mainly based on the S-P time intervals and the magnitude determination is mostly due to the maximum amplitude recorded by old-fashioned seismographs. For older events, the determination is more dependent on the seismic intensity distributions. The catalog (Table 7) lists 555 earthquakes of M≧5.9 and 53 destructive earthquakes of M ≧5.8. The procedure for the focal parameter determination is explained in detail using six sample earthquakes. Referring to the epicenter maps constructed from this catalog, characteristics of the seismicity of Japan in the period 1885-1925 are described. More detailed studies using this catalog will be given elsewhere. A special description of 79 selected earthquakes of particular interests is given in the last half of the paper.

著者

宇津 徳治

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.54, no.2, pp.253-308, 1979-12-25

---

Only one catalog has been available for moderate to large earthquakes occurring in the region of Japan in the years 1885 to 1925. However, this catalog, published by the Central Meteorological Observatory in 1952, has often been criticized as misleading, because no con- sideration is given to the depth of focus and magnitude values are unreasonably large for many earthquakes. A new catalog of earthquakes of M≧6 is prepared in this study to meet the demand in earthquake prediction and earthquake risk studies in Japan. Both instrumental and macroseismic data are used in the determination of focal parameters. Most of the data are taken from either published reports of the Central Meteorological Observatory, the Imperial Earthquake Investigation Committee, or written station reports collected and stored by the Japan Meteorological Agency and the University of Tokyo. The hypocenter location is mainly based on the S-P time intervals and the magnitude determination is mostly due to the maximum amplitude recorded by old-fashioned seismographs. For older events, the determination is more dependent on the seismic intensity distributions. The catalog (Table 7) lists 555 earthquakes of M≧5.9 and 53 destructive earthquakes of M ≧5.8. The procedure for the focal parameter determination is explained in detail using six sample earthquakes. Referring to the epicenter maps constructed from this catalog, characteristics of the seismicity of Japan in the period 1885-1925 are described. More detailed studies using this catalog will be given elsewhere. A special description of 79 selected earthquakes of particular interests is given in the last half of the paper.

著者

宇津 徳治

出版者

北海道大学理学部地球物理学教室

雑誌

北海道大学地球物理学研究報告 (ISSN:04393503)

巻号頁・発行日

vol.21, pp.45-52, 1969-02-15

著者

宇津 徳治

出版者

北海道大学理学部地球物理学教室

雑誌

北海道大学地球物理学研究報告 (ISSN:04393503)

巻号頁・発行日

vol.20, pp.51-75, 1968-09-20

著者

宇津 徳治

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.60, no.4, pp.639-642, 1986-03-31

著者

宇津 徳治

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.61, no.4, pp.p551-561, 1987-03

被引用文献数

2

---

日本のマントル最上部地震(深さ40~80km程度,ただし異常震域が現れる東日本の太平洋岸沖合の地震や北海道太平洋沿岸の地震を除く)に対する震度I(気象庁震度階級),震央距離Δ(km),マグニチュードM(気象庁方式)の標準的関係を表す実験式を132個の地震(M : 5~7)の震度データを用いて求めた.I-Δの平均回帰直線I=I100-b(Δ-100)の定数を,次の式でMと結んだものを提出する.I100=1.5M-6.1 b=0.0523-0.0063Mこれらの式によりあるM,Δに対する震度を求めたとき,得られた値の小数点以下を四捨五入したものが整数値で表される通常の震度になる.

著者

宇津 徳治

出版者

公益社団法人 日本地震学会

雑誌

地震 第2輯 (ISSN:00371114)

巻号頁・発行日

vol.31, no.4, pp.367-382, 1978-12-25 (Released:2010-03-11)

参考文献数

7

被引用文献数

5 18

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In many cases, the log-frequency vs magnitude curves for earthquakes show considerable curvature, though the well-known G-R (Gutenberg-Richter) formula predicts a straight line. To represent such data, two modifications of the G-R formula have been proposed.log n(M)=a-bM M≤cn(M)=0 M>c} (2)and log n(M)=a-bM+log(c-M) M<cn(M)=0 M≥c} (3)These are called here the truncated G-R formula and the modified G-R formula, respectively. These equations can be written in the form of probability density function:f(x)=B/1-e-BCe-Bx C≥x≥0 (5)f(x)=B2/e-BC+BC-1e-Bx(C-x) C>x≥0 (6)where x=M-MS, B=b ln 10, C=c-MS, and MS is the lower limit of magnitude above which the data is complete.The estimation of B and C in equation (5) by the method of moments was discussed by Okada (1970) and Cosentino et al. (1977). The equations proposed here areexpC(C-2x)/Cx-x2=C2-2Cx-x2/2x2-x2 (16)B=(2x-C)/(x2-Cx) (15)or x2/x2=2-BC(BC+2)/(eBC-1)/1-BC/(eBC-1) (18)Bx=1-BC/(eBC-1) (19)The maximum likelihood method for equation (5) yields only one equation (equation (19), Page (1968), Okada (1970)). If we adopt C=Max(xi) as the second equation, the C value is considerably biased. To correct the bias, a correction ΔC which is a function of B and C is proposed. For this correction we must use some estimated values for B and C.To estimate B and C in equation (6) by the method of moments the following equations are used.x2/x2(e-BC+BC-1){e-BC(B2C2+4BC+6)+2BC-6}/{e-BC(BC+2)+BC-2}2 (25)Bx=e-BC(BC+2)+BC-2/e-BC+BC-1 (23)The maximum likelihood estimates of B and C in equation (6) can be obtained by the equation:2-Bx=C/S ∑Si=1 1/C-xi=BC(1-e-BC)/e-BC+BC-1 (27), (29)The accuracy of B and C values determined by the above methods is estimated by Monte Carlo technique for the cases of S=50, 100, 200, 400, and 800 and several values of B and C. If we adopt the truncated G-R formula, the second method (which uses C=Max(xi)+ΔC) gives more accurate C values, whereas the accuracy of B values is almost the same as that obtained by the method of moments. If we adopt the modified G-R formula, the maximum likelihood method gives more accurate B and C values than the method of moments. The η value (η=x2/x2) is a useful index for the deviation of the distribution of data from the G-R formula (for the G-R formula, theoretical value for η is 2). An application of the present methods shows regional variations in b, c, and η values of shallow earthquakes in Japan.

著者

宇津 徳治

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.60, no.4, pp.639-642, 1986-03-31

著者

宇津 徳治

出版者

公益社団法人 日本地震学会

雑誌

地震 第2輯 (ISSN:00371114)

巻号頁・発行日

vol.28, no.4, pp.435-448, 1975-12-10 (Released:2010-03-11)

参考文献数

9

被引用文献数

1 2

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About 400 shallow earthquakes in central Japan occurring during 1967-1974 have been relocated using data supplied by the Japan Meteorological Agency and several university seismic stations. About 4200 P-residuals are obtained in the relocation. The residual is approximately normally distributed with a mean of 0.0sec and a standard deviation of 0.59sec. Therefore, the probability that a residual exceeds 0.4sec is 0.25. If the actual travel-time for paths crossing the focal region of an impending earthquake is increased by 0.4sec, the probability that an observed residual for one of these paths exceeds 0.4sec will be 0.50. Let R denotes the ratio of the number of paths with residuals larger than 0.4sec to the total number of the paths crossing a certain region. The R-values for the focal regions of the central Gifu earthquake of 1969 (M=6.6), the Izu-hanto-oki earthquake of 1974 (M=6.9), and other 24 earthquakes of smaller magnitudes during some time-intervals before the occurrence of them have been determined to be about 0.5 or more. These values suggest the decrease in P-velocity before the earthquakes. A map has been made showing the distribution of R-values in 204 areas of 0.2°×0.2° in central Japan. Significantly high R-values are found in the areas containing the focal regions of the above-mentioned two earthquakes in the maps covering certain periods before the earthquakes. However, there are many other areas of high R-values, which are not connected with the occurrence of large earthquakes until now. Most of these areas may correspond to inherent low-velocity regions in the crust.

著者

宇津 徳治

出版者

公益社団法人 日本地震学会

雑誌

地震 第2輯 (ISSN:00371114)

巻号頁・発行日

vol.47, no.2, pp.183-183, 1994-08-14 (Released:2010-03-11)

参考文献数

2

著者

宇津徳治著

出版者

共立出版

巻号頁・発行日

2001