著者

石橋 克彦 佐竹 健治

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.50, no.appendix, pp.1-21, 1998-03-31 (Released:2010-11-17)

参考文献数

164

被引用文献数

35

---

We review long-term forecasts of great earthquakes along subduction zones around Japan and discuss the related problems from a paleoseismological point of view. Rich historical data in Japan show the recurrence of great earthquakes along subduction zones, particularly at the Nankai trough, for more than 1, 000 years. On the basis of such historical data and interseismic/coseismic vertical crustal movements, Imamura made a rather vague forecast of great earthquakes along the Nankai trough as early as 1933, which turned out to be successful by the occurrence of the 1944 Tonankai (Mw 8.1) and 1946 Nankai (Mw 8.1) earthquakes. After plate tectonics theory was established, the concept of seismic gap in subduction zones has been thought as a powerful tool for long-term earthquake forecasts. Great interplate earthquakes have been predicted from examinations of not only seismic gaps but also other observations such as seismic quiescence, earthquake recurrence history, current crustal deformation in coastal areas, or seismic crustal movements in geologic records. The 1973 Nemuro-oki earthquake (Mw 7.8) along the Kurile trench was predicted in 1972, although it was slightly smaller than the predicted size. The 1978 Miyagi-oki earthquake (Mw 7.6) along the Japan trench was also predicted in 1977, although the size and place were somewhat different from the prediction. The Tokai earthquake was predicted in 1976, and its occurrence has been considered imminent. Despite that short-term surveillance system has been in operation in the last 20 years, this earthquake has not occurred yet. In 1994, two great/large earthquakes occurred in subduction zones off northeast Japan, but no forecasts had been made on these. The off-Hokkaido event (Mw 8.2), whose aftershock area apparently coincides with that of the 1969 interplate earthquake (Mw 8.2), has been interpreted as an intraplate event within the subducted Pacific slab. The Sanriku-oki earthquake (Mw 7.7) was aninterplate event, but its rupture zone overlapped with a previous interplate event, the 1968 Tokachi-oki earthquake (Mw 8.2). The recurrence history of interplate earthquakes along the Nankai trough has been updated by seismo-archaeologlcal data such as liquefaction evidence at archaeoiogical sites. and it now seems more regular and can be explained by time-predictable model. In the mean time. historical data indicate that the 1605 earthquake was an unusual “tsunami earthquake” and the source process is very different from the other repeated events. This event may have been affected by a preceding large inland earthquake in 1596. Paleoseismological investigation is still very important for long-term forecast of earthquakes. Future research should emphasize to complement recurrence history of interplate earthquakes from historical as well as seismo-archaeological data, to distinguish intraplate (slab) earthquakes from interplate earthquakes in historical catalog, to investigate the co-relation between interplate and inland earthquakes, and to combine historical, geologic and other kinds of data to study earthquake recurrence as demonstrated in the Cascadia subduction zone.

著者

羽鳥 徳太郎

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.43, no.2, pp.227-232, 1990-06-24 (Released:2010-03-11)

参考文献数

17

被引用文献数

5 5

---

It is reported by an old document that the Yamagata-Oki earthquake of Dec. 7, 1833 (Oct. 26, Tenpo 4), hitting the Yamagata, Niigata and Akita districts destroyed 475 houses in the Shonai plain and the tsunami killed about 150 persons. In this paper the distributions of the seismic intensity and the tsunami behavior along the Japan Sea coast are investigated with an addition of newly collected data. The magnitudes of earthquake and tsunami are compared with those of the 1964 Niigata and the 1983 Japan Sea earthquakes. The results are summarized as follows:1) According to the intensity-distance diagram, the earthquake, magnitude is inferred as M=7.5, because the same intensity area is smaller than that of the 1983 Japan Sea earthquake and similar to that of the 1964 Niigata earthquake.2) By judging from the tsunami height-distance diagram (HATORI, 1986), tsunami magnitude on the Imamura-Iida scale is m=2.5, which are somewhat larger than the former value. Extraordinary run-up heights at Wajima (tip of Noto peninsula) and Oki Islands located in far field may be caused by the refractive effect and the reflected waves from the continental coasts.

著者

武村 雅之

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.50, no.4, pp.377-396, 1998-03-13 (Released:2010-03-11)

参考文献数

28

被引用文献数

2

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Strong ground motion in Tokyo metropolis during the Sep. 1, 1923 Kanto earthquake was important factor for determining the seismic design code in Japan. However, it has not been clarified in detail, because of no strong motion record near the source region of the Kanto earthquake. The author collected the descriptions and made a data set of 548 personal experiences in and around the southern Kanto district to investigate the strong ground motion from the Kanto earthquake. Many descriptions in Tokyo metropolis indicated that three severely strong shakings arrived at this area during the Kanto earthquake. The first shaking was, of course, caused by the main shock (M=7.9) at 11:58AM (JST). The second and the third shakings were caused by the aftershocks occurring 3 minutes and 4.5 minutes after the main shock, respectively. These aftershocks were identified on a seismogram obtained at Gifu observatory and magnitudes of them were determined to be 7.2 and 7.3, respectively from this seismogram [TAKEMURA (1994)]. The results of the analyses of the personal experiences also indicated that the duration time of the first shaking due to the main shock was 30 to 40sec. The strength of the second shaking was as strong as the first shaking, of which seismic intensity was estimated to be VI in JMA scale, while duration time of the second shaking was shorter than the first shaking. On the other hand, the third shaking was weaker than the first and the second shakings, of which seismic intensity was estimated to be V. The sequence of strong shakings within 5 minutes after the occurrence of the main shock of the 1923 Kanto earthquake was elucidated in Tokyo metropolis in the present study.

著者

藤原 広行

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.66, no.4, pp.67-71, 2014-03-25 (Released:2014-05-20)

参考文献数

20

---

There is a similarity between the distribution of prime numbers and the pattern of earthquake occurrence. Earthquakes occur in a discrete manner in time and space. When viewed as a whole, however, we find some laws, such as Gutenberg-Richter law, that govern the entire earthquakes that seem to be individually independent. A similar phenomenon can be observed also in the world of number. The most basic example is the distribution of the prime numbers in integers. We consider a correspondence between earthquakes and prime numbers. We parameterize occurrence time of earthquakes as the prime numbers and magnitude of earthquakes as the interval of prime numbers. Then we obtain a relationship similar to Gutenberg-Richter law. We call the model obtained by this correspondence as “arithmetic seismic activity model”. If we can parameterize earthquakes using prime numbers, knowledge that has been cultivated in the number theory can be used for understanding of earthquakes. The distribution of prime numbers is related to the distribution of zeros of Riemann zeta function. Researches are in progress to understand the zeros of the Riemann zeta function as an eigenvalue problem of quantum dynamical system. Earthquake may be modeled as a phenomenon corresponding to a change in the energy level of a quantum dynamical system associated with prime numbers.

著者

佃 為成 溝上 恵

出版者

日本地震学会

雑誌

地震 (ISSN:00371114)

巻号頁・発行日

vol.2, no.41, pp.47-57, 1988

著者

加藤 護

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.70, pp.153-160, 2017-09-10 (Released:2017-10-11)

参考文献数

36

---

An MJMA 6.7 (Mw 6.2) earthquake occurred in Northern Nagano, Japan, on November 22, 2014. While the damage in the city center of Nagano was relatively minor, 65 stone lanterns, among 182, standing in the precinct of the Zenkoji Temple, approximately 25 km from the epicenter, were toppled by the ground motion of this earthquake. Damage of the surrounding residential area was minor. Directions of the collapse were dominantly in the north-south. Strong motion seismograms recorded at nearby JMA Nagano Local Meteorological Observatory were rich in high frequency, especially in the NS component, which explains collapse of stone objects whose natural periods are few tenths of a second. Similar damage was documented in a historic earthquake in 1714, and recurrence of such damage implies that high frequency ground motions from large earthquakes in this epicentral area have been repeated threats to the Zenkoji Temple and Nagano City.

著者

山中 浩明 瀬尾 和大 佐間野 隆憲 翠川 三郎

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.39, no.4, pp.607-620, 1986-12-25 (Released:2010-03-11)

参考文献数

21

---

The seismic refraction prospecting was carried out in the southwestern part of the Tokyo Metropolitan area, to clarify the deep underground structure down to uppermost layer of the Earth's crust. The explosions were denoted at Nagatsuta, Kurokawa, Okazu and Yumenoshima. The explosion at Nagatsuta was planned to make clear the existence of vertical discontinuity of the basement between Nagatsuta and Yumenoshima, which has been suggested from the observation of Yumenoshima explosion. The underground structure was revealed by the travel time analysis. The main features of the underground structure are as follows:1) The underground structure consists of 4 layers. The P wave velocities of these layers are 1.8 to 2.0, 2.9, 4.8 and 5.5km/s, respectively.2) The thickness of the third leyer is several kilometers in this area, however this layer doesn't exist in the central part of the Kanto plain.3) The first layer is thinner than the second one in contrast with the underground structure of Yumenoshima situated on the center of the Kanto plain.4) The vertical discontinuity of the basement was not confirmed from Nagatsuta explosion, because the refracted wave from the basement was not observed as an initial motion at the expected stations.

著者

田中館 秀三

出版者

公益社団法人 日本地震学会

雑誌

地震 第1輯 (ISSN:00371114)

巻号頁・発行日

vol.10, no.12, pp.529-542, 1938-12-25 (Released:2010-03-09)

被引用文献数

1

著者

後藤 和彦

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.65, no.3, pp.231-242, 2013-01-31 (Released:2013-07-19)

参考文献数

28

被引用文献数

7 9

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The hypocenter of the 1911 great earthquake occurred around Kikai-jima, Japan is thought to be 28.0°N, 130.0°E (about 30km southward from Kikai-jima) and 100km depth in general. This implies that the 1911 event occurred within the subducting slab at the Ryukyu trench. However, it is not clearly known what kind of seismic data were used to determine the epicenter and how the depth of hypocenter was estimated quantitatively. In the present study, we determine hypocenter of this event by using selected S-P time data not only reported ones but also re-measured ones from smoked-paper seismograms. The hypocenter is revealed to be 28.7°N, 130.6°E and 60km in depth, about 60km northeastward from Kikai-jima. The focal depth is, however, considered to be about 10km instead of 60km by referring to the present hypocenter distribution because of the low reliability of focal depth in the relocation. Recent epicenter distribution shows the low seismic activity area on the plate boundary northeast off Kikai-jima which extends about 70km length parallel to the Ryukyu trench axis. The 1911 great earthquake seems to be occurred at the shallower rim of this low seismic activity area. If the low seismic activity is the result of strong coupling on plate boundary, this area might be the asperity of the 1911 great earthquake. Tsunami heights accompanied with this event are reported recently to be more than 5m at Kikai-jima and Amami-oshima, which supports the present study that the 1911 great earthquake is the interplate event rather than the intraslab one.

著者

武村 雅之 池浦 友則 工藤 一嘉 大沼 啓人

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.193-200, 1994-08-14 (Released:2010-03-11)

参考文献数

15

被引用文献数

4

著者

加藤 護 岡本 義雄

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.69, pp.35-39, 2016-11-10 (Released:2017-01-07)

参考文献数

40

著者

佐々木 晶

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.61, no.Supplement, pp.285-296, 2009-07-31 (Released:2013-11-21)

参考文献数

46

---

The interior structures of planets and satellites have been investigated through various methods. Density is the most fundamental information for estimating the composition of solar system bodies. Moment of inertia expressing the mass concentration is a key for investigating the interior structure. It can be obtained from spacecraft flyby with a planet or a satellite. Interior density structure of a planet is evaluated from gravity field which is estimated from orbital tracking of spacecraft around the planet. KAGUYA first successfully obtained the accurate far-side gravity field of the Moon. Detailed interior structure can be estimated from seismic methods. Direct seismic measurements had been developed on the nearside of the Moon by the Apollo project. Seismograms of moonquakes, reflecting less interior dissipation, are different from those of the Earth. Radar sounders have been successful in measuring subsurface structure of the Moon and Mars. The state of the planetary interior, especially of the core, can be discussed using the measurement of variation of planetary rotation. The study of the planetary interior is now being extended into extrasolar planets.

著者

小林 芳正

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.1, pp.57-73, 1979-03-25 (Released:2010-03-11)

参考文献数

13

被引用文献数

2 2

---

The Great Kanto earthquake, 1923, triggered a catastrophic debris flow which devastated the village of Nebukawa with a loss of 300 to 400 lives. The buried area at Nebukawa is determined by synthesizing eyewitness accounts, photographs, the character of surface soils, etc. The moment of rushing at Nebukawa is estimated at about 5 minutes after the mainshock onset from the eyewitness accounts and aftershock records. The temporal change in topography in the mountain region is investigated by comparing topography maps prior and after the earthquake, and a probable source of the debris flow is assumed at a large depressed area, Obora about 4km upstream Nebukawa. The grain-size distributions of the debris-flow deposits and those of mountain soils are also consistent with this assumption.

著者

大見 士朗 和田 博夫 濱田 勇輝

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.65, no.1, pp.85-94, 2012-09-28 (Released:2012-10-26)

参考文献数

15

被引用文献数

2 3

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Seismic activity near the Yake-dake (Mt. Yake) volcano in the Hida mountain range that took place immediate after the 2011 off the Pacific Coast of Tohoku earthquake was investigated. It initiated about ten minutes after the mainshock of the Tohoku earthquake and lasted for about one month. At the beginning, two active swarms were observed. One is at the northern flank of the Yake-dake volcano and the other is located between Yake-dake and Mt. Norikura volcanoes. The latter activity decreased by March 20, and the former activity lasted until early April. It includes two M≥4.5 earthquakes and we could locate more than 9,600 events in the study area during March and April. We mainly focused on the activity near the Yake-dake volcano in this paper. Near the Yake-dake volcano, seismic activity began with M4.7 (JMA) earthquake at 14:57 JST on March 11. This M4.7 event is located 3 km north to the volcano and seismicity increased between the summit of the Yake-dake volcano and the hypocenter. On March 21, an M4.8 (JMA) event took place at 13:15 JST also at 3 km north to the volcano. After this second M≥4.5 earthquake, seismic activity migrated to the north about 1 km. Focal mechanism solutions of these swarm earthquakes show NW-SE compression stress field, which coincides with regional stress field indicated by previous studies. No temporal changes of focal mechanisms are shown during March and April, which probably indicates no magmatic activity such as dyke intrusion related to the Yake-dake volcano took place in this time period.

著者

阿部 邦昭

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.49, no.1, pp.1-9, 1996-05-24 (Released:2010-03-11)

参考文献数

15

被引用文献数

2 2

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Local amplifications of tsunami were found on the maximum inundation heights at Japanese 10 coasts facing islands in the 1993 Hokkaido nansei-oki earthquake tsunami. For each island-coast geography a peak height (H) at a coastal focus, a background average height (H0), a peak width (Wd), a coastal focus distance from the island (L) and an island size (L0) are defined on the space distribution of maximum heights obtained in the surveys and the relations are discussed.Main results are as follows: Amplification ratio H/H0, plotted as a function of coastal focus distance from an island, are distributed in the vicinity of 2. The peak width relative to the island size Wd/L0 is proportional to the focus distance relative to the island size L/L0. There is a negative correlation relation between the amplification ratio and the relative peak width. These facts suggest that the amplification was caused by a superposition of incident waves on the sea in the rear of the island slope after being separated into two and refracted on the slope. Thus, the amplification at the coast facing islands is explained from a focusing effect of islands on a tsunami.

著者

今村 明恒

出版者

公益社団法人 日本地震学会

雑誌

地震 第1輯 (ISSN:00371114)

巻号頁・発行日

vol.5, no.9, pp.585-595, 1933-09-15 (Released:2010-11-17)

著者

岩田 貴樹

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.61, no.Supplement, pp.133-141, 2009-07-31 (Released:2013-11-21)

参考文献数

70

被引用文献数

3

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In recent years, many researchers in seismicity analysis have focused on earthquake triggering or fault interactions.To evaluate these phenomena quantitatively, models for the spatio-temporal distribution of seismic activity have been constructed. This review paper introduces two important models : the ETAS (epidemic-type aftershock sequence) model developed by Y. Ogata and a seismicity model based on rate- and state-dependent friction law by J. Dieterich. The former is a pure statistical model, while the latter includes some physical parameters in its derivation.These two models now play separate role in probabilistic earthquake forecasting. For further achievement in the probabilistic earthquake forecasting, the integration of the two contrasting models should be considered. Further development of models would give new insights into earthquake occurrence.

著者

田村 慎 笠原 稔 森谷 武男

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.55, no.4, pp.337-350, 2003-03-15 (Released:2010-03-09)

参考文献数

27

被引用文献数

4 4

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We have studied micro-seismicity in the northern part of Hokkaido (north above 44°N) from June to November in 1998 combining eleven temporal seismic stations with seven and five routine ones operated by Institute of Seismology and Volcanology (ISV) in Hokkaido University and Sapporo Meteorological Observatory, Japan Meteorological Agency (SMO), respectively.Firstly we determined 91 hypocenters of local earthquakes in this period using the dense network. These hypocenters are about three times of the number of those from the routine network alone. One-dimensional P-wave velocity structure assuming four-layer model (assumed thickness of 2, 8, 10km and infinite) and station corrections were estimated using a P-wave travel time inversion method with 735 P-wave arrival time records of 81 events. The velocity of each layer was determined to be 2.83km/sec for the first layer, 5.32km/sec for the second one, 6.32km/sec for the third one and 6.69km/sec for the bottom half space. From the P-wave station corrections we obtained, this region can be classified into three zones parallel in the north-south direction; the western islands region in the Sea of Japan, the western part of mainland, and the eastern part of mainland. Each zone shows the value of less than-0.5sec, +0.1-+0.4sec, and-0.1--0.5sec, respectively.Next, the hypocenters with the inverted velocity structure and the station corrections are relocated. As the results show, some hypocenters in the anomalous delayed station correction zone, i. e. the western part of mainland, are clearly located at the depth range from 20 to 25 km. Focal mechanism solutions of these deep events show normal fault type, while shallower events less than 20 km depth show strike-slip and reverse fault types. We also relocated 381 earthquake hypocenters which were routinely determined by ISV from October 1996 to December 2000. According to the relocated hypocenter distribution, a high seismic zone is shown in the western part of mainland with about 50km wide along a north-south direction. On the other hand, the eastern part of mainland is strongly characterized as aseismic zone. The boundary between the seismic and aseismic zones corresponds to the geological boundary between Kamuikotan metamorphic belt and Hidaka belt.

著者

束田 進也 小高 俊一 芦谷 公稔 大竹 和生 野坂 大輔

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.56, no.4, pp.351-361, 2004-03-25 (Released:2010-03-11)

参考文献数

18

被引用文献数

11 27

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We have found that the envelope waveform of the initial part of P waves changes systematically with magnitude and epicentral distance. In order to represent the envelope waveform quantitatively we introduced a simple function of the form of Bt·exp(-At). Two parameters A and B can easily be determined by the least-squares method. The parameter B defines the slope of the initial part of the P-wave envelope and A is related to the amplitude growth or decay with time. When A is positive, B/(Ae) gives the maximum amplitude where e denotes the base of natural logarithm. This case is typical for small earthquakes, indicating that the initial amplitude increases sharply and decays quickly soon after the P-wave arrival. When A is negative, the amplitude increases exponentially with time. This is a characteristic of large earthquakes.We have found from the analysis of actual seismic data that log B is inversely proportional to the epicentral distance Δ even though the dispersion of data is somewhat large. This relation seems to be independent of earthquake magnitude and thus, by using this relation, we can roughly estimate the epicentral distance immediately after the P-wave arrival. Then, we can estimate the magnitude easily from the formula, similar to the conventional magnitude-amplitude relation, M=α·logVmax+β·logB+γ, where Vmax is the P-wave maximum amplitude within a given short time interval (e. g., 3 seconds) after the P-wave arrival. For M7- and M8-class earthquakes whose rupture duration reaches 10 sec or more, we need to estimate the magnitude repeatedly with time as the amplitude increases.The decrease of the parameter B with distance may be caused by anelasticity of the medium, scattering and geometrical spreading of P waves during propagation.

著者

加納 靖之 大邑 潤三 山村 紀香 濱野 未来

出版者

地震学会

雑誌

地震 第2輯 (ISSN:00371114)

巻号頁・発行日

vol.72, pp.53-56, 2019