著者

加藤 祐三 森 宣雄

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.48, no.4, pp.463-468, 1996-03-12 (Released:2010-03-11)

参考文献数

10

---

The records on a disastrous earthquake of July 25, 1882, southern Okinawa Island were discovered for the first time from nine archives. The most important are: “Okinawa-nisshi” written by Hatakeyama, a secretary of prefectural governor Uesugi; “Ryukyu-iki-nisshi” written by Ozaki, high official, dispatched from the central government to inspect a political situation in the Okinawa Prefecture; the official diary of the Okinawa Prefecture; and, the official document from the Okinawa Prefecture to the central government. Synthesizing these records, the earthquake happened between 1 and 2a. m., on July 25th, 1882, and aftershocks were intermittent for seventy days following. While there were no casualties, 500 stone walls were broken in Naha City. Analysing these records, the seismic intensity of this earthquake was probably 5. The reason why this earthquake was not discovered for about one hundred years is, firstly, the records of “Kyuyo”, an official document of the Ryukyu Kingdom, had already stopped, because the Kingdom was ruined three years before the earthquake, and secondly, the Japanese earthquake observation system was insufficient at the time of the earthquake.

著者

飯田 汲事

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.3, pp.266-274, 1971 (Released:2010-03-11)

参考文献数

32

被引用文献数

2 2

---

There have been developed a number of relations between seismic wave energy E and the magnitude M of an earthquake. The general form of the relation is written as logE=α+βM. in which α, β are constants and M is the surface-wave magnitude. A number of relations were presented as given in Table 1 where α and β are listed. The relationship between α and β seems to keep linearity as shown in Fig. 1. This relation can therefore be expressed as α=(26.10±0.91)-(9.60±0.72)β for 5.3≤M≤8.5 (1) α=(19.11±0.70)-(4.59±0.40)β for -2.1≤M≤5.3 (2) An energy-magnitude relation for large earthquakes having magnitude larger than 5 seems to be different from that for small earthquakes having magnitude smaller than 5.The lines expressing (1) and (2) intersect at the point α=12.66, β=1.40. Thus, a new magnitude-energy relation which is appropriate for both large and small earthquakes is obtained as logE=12.66+1.40M. By using the relations between α and β in (1) and (2), seismic efficiency factor f was obtained as 0.04-0.90 from some examples.

著者

渡辺 偉夫

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.21, no.4, pp.293-313, 1969-02-25 (Released:2010-03-11)

参考文献数

30

被引用文献数

2

---

Table of tsunamis which occurred in and near Japan was prepared. The table consists of two parts. One part (Table 1) is the table of tsunamis caused by earthquakes, vocanic eruptions and landslides which occurred in and near Japan. Another one (Table 2) is the table of tsunamis which occurred in the Pacific Ocean and additionally invaded Japan and its vicinity.1) Table 1.The contents of the table are:a) Sequential numberb) Date in the Christian and Japanese Calendar (Time in Japanese Standard Time)c) Location of tsunami source or epicentral region together with longitude, latitude and depth of hypocenterd) Magnitude of earthquakee) Grade magnitude of tsunami by Dr. A. IMAMURA and Dr. K. IIDAf) Description of earthquake and tsunami.Magnitude of earthquake, and longitude, latitude and depth of hypocenter were taken from the “Rika-nenpyo (1968)”, the “Catalogue of major earthquakes which occurred in and near Japan, supplementary volume No. 1 (1958), No. 2 (1966) and No. 3 (1968)” and the “Zisin-geppo (1968)”.2) Table 2.The contents of the table are:a), c) and f) The same content as the Table 1b) Date in the Christian Calendar (Time in Greenwich Mean Time)e) Grade magnitude of tsunami occurred in the Pacific Ocean and invaded Japan and its vicinity.Magnitude of earthquake, and longitude, latitude and depth of hypocenter were taken from the “Seismicity of the Earth and Related phenomena (1954)” and the report of the U. S. Coast and Geodetic Survey.

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.2, pp.129-135, 1978-07-31 (Released:2010-03-11)

参考文献数

7

被引用文献数

2 1

---

Discrimination of foreshock sequences from earthquake swarms is an important problem in earthquake prediction. In this paper, the magnitudes of the largest, the second largest, and the third largest shocks in an earthquake swarm or foreshock sequence are denoted by M1, M2, and M3, respectively, and Japanese shallow earthquake swarms and foreshock sequences (with M1-M2≤0.6 and M1≥5.0 for 1926-64 or M1≥4.5 for 1965-77) are classified according to the values of M1-M2 and M1-M3, and the time sequence of the shocks of M1 and M2. If we select the earthquake swarms and foreshock sequences satisfying the following conditions, the highest proportion of foreshock sequences to earthquake swarms is achieved. The conditions are: (1) 0.4≤M1-M2≤0.6, (2) M1-M3≥0.7 (or M3 is too small to be determined), and (3) the shock of M2 precedes the shock of M1. The numbers of foreshock sequences and earthquake swarms selected under these conditions are 10 and 17, respectively, while the total numbers of foreshock sequences and earthquake swarms are 13 and 232, respectively. It is confirmed that the above criterion is also effective, if it is used during the course of an earthquake sequence.

著者

細山 謙之輔

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.5, no.2, pp.45-48, 1952-06-15 (Released:2010-03-11)

参考文献数

6

---

Secular change of latitude was compared with those of some geophysical phenomena. It was found that there existed an intimate correlation between the secular displacement of the earth's mean pole and the change of height of mean sea levels of the Atlantic Ocean and Pacific Ocean.On the other hand, the Chandlerian amplitude and period showed a parallel change with the amplitude of tidal variation of latitude.In both cases a geoid pulsation may be postulated.

著者

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.47, no.3, pp.333-340, 1994-10-14 (Released:2010-03-11)

参考文献数

54

---

In order to deepen understanding of the characteristics of near-field ground motion, case histories of upthrow of objects during 21 earthquakes are reviewed. The fault distance to the site where the upthrow was observed becomes larger with increase of the earthquake magnitude. The area where the upthrow was observed roughly corresponds to that of the J. M. A. intensity VII which is X or greater in the M. M. scale. The upthrown objects are boulders, stone mouments, human bodies, small structures and wooden houses, with limitation in size. In case of the boulder, one on a shallow socket of surface soil and with the diameter of approximately 50cm tends to have a large displacement. These facts may suggest the soil-object interaction system with a limited vibration period causes a large response of the object and the resulting upthrow under strong shaking of the M. M intensity X or greater.

著者

大滝 壽樹 吉田 康宏 神定 健二

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.2, pp.27-30, 2013-09-19 (Released:2013-10-16)

参考文献数

6

著者

杉崎 隆一 志知 龍一

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.2, pp.195-206, 1978-07-31 (Released:2010-03-11)

参考文献数

21

被引用文献数

1 1

---

The utility of the ratios of He/Ar and N2/Ar of fault gases as an earthquake precursor was discussed and examined. The ratio of helium to argon produced in the lithosphere remains rather constant (≅10) for the past several hundred million years irrespective of rock types. The ratio in the lithospheric air amounts to 105 times higher than that of the atmospheric air (5.7×10-4). The lithospheric air released by the formation of cracks and migrated by the stress in rocks prior to earthquakes, therefore, can be easily detected by means of the ratio. The N2/Ar ratio is also expected to be a useful parameter of a lithospheric air, because the ratio in natural gases and volcanic gases is generally higher than that of the atmospheric air. These ratios do not change a dilution process by other gases such as CH4 and CO2, and accordingly the ratios are more useful parameter of lithospheric air than a single element. The ratios of He/Ar and N2/Ar are gas-chromatographically measured without vacuum processes, temperature and pressure corrections and other complicated treatments.The result of successive measurement, since 1976, of the ratios in a fault at Inuyama Crustal Movement Observatory, Nagoya University, indicated that the ratios continuously fluctuated and the peak in the variation of the ratios of He/Ar and N2/Ar appeared prior to the most felt earthquakes in Nagoya (M≥4). The peaks of He/Ar preceeded those of N2/Ar for all events, which might be attributed to the difference in diffusion velocity of He and N2 through capillary cracks. The time lag of N2/Ar peak in case of the large earthquake is longer than that of the others. These features emerged in the variation of the ratios can possibly provide a practical mean of predicting earthquakes.

著者

岡村 行信

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.71, pp.185-199, 2019

被引用文献数

5

---

<p>An active fault map of Japan Sea was compiled based mainly on bathymetric data and seismic profiles that cover shelves to slopes between 4 to 150 km from the coasts of Japan Islands. The seismic profiles using air guns as seismic sources revealed active faults that have slipped during the last 104 to 106 years. In addition, high-resolution seismic profiles using a boomer as the seismic source were obtained along seaward extensions of onshore active faults in shallow sea areas less than 150 m below sea-level, and activity of the faults during the last 104 years was identified. In northeastern Japan Sea, to the northeast of the Noto Peninsula, many reverse faults accompanying large hanging wall anticlines (>750 m uplift) are concentrated in two N-S trending fault zones along the Okushiri and Sado ridges. Earthquakes larger than M 7.5 in 1940, 1964, 1983 and 1993 occurred in these fault belts. Three NE-SW trending fault zones cross the N-S trending fault zones and disrupt the structure of the N-S fault zones. In the offshore area from the Noto Peninsula to the Tango Peninsula, active reverse faults accompanying smaller hanging anticlines (<375 m uplift) are identified in a zone trending subparallel to the coasts. In addition, NW-SE to N-S trending strike-slip and reverse faults extend from onshore to offshore. In the offshore area to the west of the Tango Peninsula, E-W and NW-SE trending active strike-slip faults are identified. The former faults developed in about 40 km wide zones sub-parallel to the coast, and the later faults are located landward of the E-W trending fault zones. Some of the later faults are extensions of onshore active faults. Unknown active faults may exist in shallow sea area along coasts where have not been thoroughly investigated. Displacements of the faults during the last 106 years are large in northeastern Japan Sea and decrease to the southwest, while slip rates of these faults during the last 104 years are inferred to have smaller differences. These faults have the potential of future earthquakes, while there is not enough data to evaluate the activities of these faults.</p>

著者

吉田 明夫 小林 昭夫 塚越 利光

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.58, no.4, pp.401-406, 2006-03-31 (Released:2010-03-11)

参考文献数

23

被引用文献数

1

---

Areal strain increased noticeably in the region around the northern boundary of the Izu Peninsula in September to December 2000 when a lot of low-frequency earthquakes occurred beneath Mt. Fuji. In the same time the seismic activity in eastern Yamanashi Prefecture became low. Since increase of the areal strain indicates reduction of the pushing force of the colliding Izu block, the decrease of seismicity in eastern Yamanashi Prefecture is easily understood. Further, because diminution of the tectonic stress beneath Mt. Fuji implies reduction of the confining pressure in the magma reservoir, we think it is probable that degassing took place in the magma to build up high pressure in the focal region near the chamber which caused the remarkable activity of the low-frequency earthquakes. We suggest the noticeable increase of the areal strain in late 2000 might be produced by a mechanical separation of the Izu block from the Philippine Sea plate or detachment of the crust of the Izu block as proposed by Seno (2005).

著者

平松 良浩 小阪 大

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.251-254, 2013

被引用文献数

1

著者

島津 康男

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.8, no.2, pp.67-74, 1955-10-20 (Released:2010-03-11)

参考文献数

4

---

Chemical structure of the earth's mantle is discussed under the assumptions that (1) chemical equilibrium and hydrostatic equilibrium are attained; (2) it is isothermal and incompressible. Based upon these assumptions, the distribution of chemical elements would be controlled by differences in their chemical affinities as well as by gravitational separation due to their density differences. Calculation of the equilibrium distribution of FeO-MgO-Fe-SiO2 system, it is concluded that FeO would increase with depth, reach maximum at a depth of several hundred kilometers, and then would decrease toward the earth's center. This result suggests the origin and the physical property of Jeffrey's 20° discontinuous layer.

著者

松浦 律子 田力 正好

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.71, pp.103-116, 2018-07-10 (Released:2018-08-09)

参考文献数

30

---

After the Russo-Japanese War, too little information about earthquakes was published by the Central Meteorological Observatory, and it has made us left in difficulty to examine earthquakes of the Taisho era precisely. Among such earthquakes, the M5.7 destructive earthquake on August 6th, 1916, in Ehime Prefecture was re-examined by the excavated same age documents. Irazu weather station and other stations, which were operated by the company of Besshi copper mine, reported the detail of this earthquake. Identification of reported places about cracks and falling rocks was done, in addition to the examination of the seismic intensity distribution left in newspapers and the Official Gazette. It is proposed to move the epicenter of this earthquake to (33.95°N, 133.4°E), where is six-km south from that in Utsu-catalogue, and closer to the Ishizuchi fault, which belongs to the Median Tectonic Line active fault zone. It is also found that this event has a felt foreshock a half day before, and a felt aftershock an hour later. This event is the first candidate of destructive earthquakes of the MTL active fault zone in the written history.

著者

永峰 康一郎 榊原 淳一 杉崎 隆一

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.42, no.2, pp.211-217, 1989-06-24 (Released:2010-03-11)

参考文献数

8

被引用文献数

2 1

---

A computer-based system for automatic seismo-geochemical observations has been developed. At Hoshina hot spring, Nagano city, as a monitoring station, a personal computer regulates observation instruments such as gas chromatograph and water flow-meter, and it records the data on its floppy disks. In this study, the data transmission with a simplified telemetry system was improved. Through a public communication line and MNP modems, the data are sent to a personal computer in our laboratory. The modem enables us to transfer the data reliably without troubles caused by noise and phase delay, because it contains the function for correcting the error during correspondence. The simple BASIC program can be easily revised for expansion of measurement instruments. In view of cost, size and simplicity, this processing system is applicable for continuous on-site measurements for seismo-geochemistry.

著者

石橋 克彦

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.72, pp.69-89, 2019 (Released:2020-01-31)

参考文献数

92

---

In leap July of the 5th year of Bunroku (in the old Japanese calendar; mostly September, 1596 in the Gregorian calendar) Bungo province (present-day Oita Prefecture) in Kyushu, southwest Japan, suffered from severe earthquake and tsunami disasters. Concerning the occurrence date of the causative earthquake, the prevailing idea is currently that a large earthquake took place on leap July 9 (September 1, 1596) in Iyo province (present-day Ehime Prefecture) in Shikoku, on the eastward opposite shore of Bungo, and another large earthquake occurred on leap July 12 in Bungo. Against this idea, I claim that a single event which can be called “the Iyo-Bungo earthquake” occurred around seven p.m. on leap July 9 in the Iyo-Bungo region based on reliable contemporary historical records. There are 69 documents on this (these) earthquake(s) printed in the existing collections of historical earthquake materials, but their values as historical records vary considerably. Since the essential principle of historiographical seismology is to utilize only reliable first-grade documents, I performed historical source criticism to select 16 contemporary materials. I referred to their original or best texts, not using texts printed in the collections. According to a record in Bungo violent ground motion collapsed shrine buildings around seven to nine p.m. on leap July 9 and a large tsunami hit Fuchu (Oita) in the twilight. In Kyoto, an autograph diary of a court noble, which is used for the first time in historical seismology, describes considerable earthquake motion around seven p.m. on leap July 9. In Hiroshima Prefecture, at Hatsuka-ichi and Itsukushima strong ground motions were felt at night on leap July 9 without damages, and at Mihara strong tremors continued from leap July 9 till 12. In Iyo, a contemporary record says a severe ground motion occurred on leap July 9 and the whole Iyo province had trouble, suggesting earthquake damages in a wide area. In Satsuma and Osumi provinces (present-day Kagoshima Prefecture), a record tells a strong earthquake on leap July 9. As a fundamental methodology of historiographical seismology, these tremors and tsunami in Bungo, Iyo, Kyoto, Hiroshima and Kagoshima on leap July 9 are considered to have been produced by an identical earthquake unless there is any counter-evidence. Leap July 12, the other proposed date of the Bungo earthquake, comes from historical materials written after 1698, which probably mistook the great Kyoto earthquake in the midnight of leap July 12 for the Bungo event. Seismic intensities are estimated to be 6 in Bungo, stronger than or equal to 5 in Iyo, 4 in Hiroshima Prefecture, 3 in Kyoto, and about 4 in Kagoshima on the JMA scale (1949-1996 version). The most simple and reasonable interpretation is that a large earthquake with the source region from around Beppu Bay off Bungo to the offshore area of western Iyo, a part of the Median Tectonic Line fault zone, took place around seven p.m. on leap July 9, whose inferred magnitude being about 7.5 (corresponding to MJMA), and the tsunami on the Bungo coast followed.

著者

束田 進也

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.575-589, 2009-07-31 (Released:2013-11-21)

参考文献数

46

---

Japan is a seismically active country, and earthquake information is indispensable in Japan. There are various systems or aspects concerning earthquake information, such as earthquake observations on scientific basis, real-time seismic data processing systems, dissemination systems of the results of processed data as earthquake information, and citizens’ understandings and utilization of the information. If the above mentioned whole flow can be called a “mechanism”, Japan is the only one that has the unique and advanced “mechanism” on earthquake information in the world. This mechanism, that can also be called one of the Japanese cultures, has not been built up in a reasonable way from the beginning but it took very long time in establishing the current mechanism. In addition, a new earthquake information provision service has been started that has the nature of earthquake forecast, not observation. Like this, the character of the mechanism has been changing. In this paper, the current Japanese earthquake information is outlined, and its issues are also described.

著者

澁谷 拓郎 平原 和朗 上野 友岳

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.199-207, 2009-07-31 (Released:2013-11-21)

参考文献数

38

被引用文献数

2

---

Receiver function analyses have been developed since the late 1970s. Receiver functions are calculated by deconvolving the vertical component from the horizontal components of teleseismic P waveforms in order to remove the complexities of the source time functions and to extract the structural information beneath seismic stations. The receiver functions are sensitive to impedance discontinuities of the earth’s interior, especially to the shear wave velocity discontinuities. Therefore, the receiver function analyses have advantages in estimating the shear wave velocity structure and imaging the shear wave velocity discontinuities. In this paper we introduce several basic topics of the receiver function analyses. Firstly, we discuss the method of the calculation of the receiver functions, pointing out weaknesses in the water level method and the multitaper method and introducing the extended-time multitaper method. Secondly, we describe the inversions of the receiver functions for the shear wave velocity structure. We show two examples with the genetic algorithm. Thirdly, we introduce the way and several examples to image the shear wave velocity discontinuities with the use of the receiver functions. Finally, we discuss issues in the receiver function analyses which have not been addressed yet but should be in the near future.

著者

竹本 修三 MORI James RIVERA Luis FRECHET Julien

出版者

SEISMOLOGICAL SOCIETY OF JAPAN

雑誌

地震 第2輯 (ISSN:00371114)

巻号頁・発行日

vol.63, no.1, pp.45-55, 2010-06-15 (Released:2012-03-26)

参考文献数

21

著者

池上 良平

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.20, no.4, pp.174-177, 1968-01-30 (Released:2010-11-17)

被引用文献数

1

著者

飯田 汲事

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.12, no.1, pp.6-14, 1940-01-25 (Released:2010-11-17)

参考文献数

19