著者

石本 巳四雄

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.48, no.9, pp.399-412, 1936-09-15 (Released:2010-10-13)

著者

田村 芳彦

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.112, no.5, pp.Plate4-Plate4, 2003-10-25 (Released:2009-11-12)

著者

石渡 明 平島 崇男 野坂 俊夫 坂野 昇平

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.99, no.4, pp.382-387, 1990-08-25 (Released:2009-11-12)

参考文献数

15

被引用文献数

1 1

著者

茂木 清夫

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.92, no.7, pp.547-554, 1984-01-25 (Released:2009-11-12)

参考文献数

13

著者

木村 学 玉木 賢策

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.94, no.2, pp.69-83, 1985-04-25 (Released:2010-10-13)

参考文献数

52

被引用文献数

1 4

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The Kuril basin was formed by back-arc spreading in Oligo-Miocene time which is deduced from bottom depth, heat flow and geological data in and around the basin. The b sin has a shape of fan which diminishes northeastward and closes just southwestern end of Kamchatka Peninsula.The fan shape strongly suggests that the basin was formed by the rotation of backarc plate (the Okhotsk Plate) around a relative rotation pole located between the Kuril Basin and Kamchatka Peninsula. Geology around the Sea of Okhotsk indicates that the clockwise rotation of the Okhotsk Plate and the fan spreading of the Kuril Basin concurrently took place in Oligo-Miocene time.

著者

横山

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.4, no.1, pp.44-44, 1892-01-25 (Released:2010-12-22)

著者

岩生 周一

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.55, no.3, pp.115-117, 1943-03-15 (Released:2010-10-13)

著者

白尾 元理 佐藤 正

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.108, no.6, pp.Plate1-Plate2, 1999-12-25 (Released:2009-11-12)

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.25, no.12, pp.885-886, 1913-12-15 (Released:2010-12-22)

著者

浜野 洋三 柳澤 孝寿 山岸 保子

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.114, no.2, pp.142-150, 2005-04-25 (Released:2009-11-12)

参考文献数

7

---

Recent progress of numerical simulations on the dynamo process in the core and the mantle convection provides a clue to understanding the origin of global variations of the Earth system during the last 150 Ma, in which long-term variations of geomagnetic reversal frequency and mantle activity are closely related in time. Recent MHD dynamo simulations suggest that the increase of the total heat flow through the CMB changes the geodynamo from stable dipolar dynamos to unstable multipolar dynamos, and on axially symmetric and equatorial symmetric pattern of heat flux produces stable dipolar dynamos. Numerical modelings of mantle convection indicate 3 convection regimes, whole-mantle, intermittent, and 2-layer convections, in a parameter space of the Rayleigh number (Ra) and the Clapeyron slope (dP/dT) of the phase transition at a depth of 660 km. In the intermittent convection regime, the convection vacillates between wholelayer and the 2-layer regimes, and the surface and CMB heat flows fluctuate with time. The global variation of the Earth system might be attributed to this intermittent convection mode of the present Earth. However, the apparent out of phase variation of the total heat flow through the CMB inferred from the reversal frequency and the mantle activity requires some mechanism for the phase shift of the variations..

著者

山下 傳吉

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.6, no.5, pp.252-258, 1894-05-25 (Released:2010-10-13)

著者

岡田 義光

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.116, no.3-4, pp.307-308, 2007-08-25 (Released:2009-11-12)

著者

池内 幸司 伊藤 夏生

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.116, no.3-4, pp.490-503, 2007-08-25 (Released:2009-11-12)

参考文献数

8

---

The Central Disaster Management Council conducted damage estimation research on the next Tokyo Metropolitan Earthquake. The estimation clarified that the earthquake would bring not only a huge amount of physical damage, but also serious influence on the metropolitan functions such as politics, administration, and economy. The “Policy Framework for Tokyo Metropolitan Earthquakes” was set to secure the continuity of metropolitan functions as well to reduce damage. The “Tokyo Metropolitan Earthquake Disaster Reduction Strategy” was also shown by setting quantitative disaster reduction objectives with definite deadlines and concrete plans to execute disaster reduction measures effectively and properly. Furthermore, the “Guidelines for Tokyo Metropolitan Earthquakes Emergency Response Plan”, which provides the contents of emergency activities in a large area, and procedures and roles of government in the event of a disaster, was regulated. Measures for evacuees and people stranded without bearable means of returning to their homes, and contingency plans for central governments are under discussion.

著者

江口 孝雄 堀 貞喜

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.116, no.3-4, pp.325-369, 2007-08-25 (Released:2009-11-12)

参考文献数

142

被引用文献数

1

---

We present a new view of the morphology of slab (s) subducted just beneath the Tokyo Metropolitan Area in Japan. Previously, several different models of the surface geometry of the subducted Philippine sea plate slab (PH slab) have been published mainly using seismicity data (e.g., Nakamura and Shimazaki, 1981; Maki, 1984; Kasahara, 1985; Ishida, 1992; Noguchi, 1998; Hori, 2006).In this study, first we discriminate a previously unknown seismic slab (called slab SG, or seismic slab SG) above the downgoing Pacific plate slab (PC slab), second identify the possible internal structure of slab SG, and third demonstrate tectonic evolution models. It is clear that the currently known surface contours of PH slab indicate the shallowest part of slab SG as well.Most previous studies assumed a PH slab with a constant thickness, and paid little attention to the tectonic characteristics of the vertical extent and/or the bottom geometry of slab SG with variable thickness. The bottom extent of the seismic slab SG beneath the Metropolitan area reaches 36.5N at least. The horizontal extent of seismic slab SG covers most of the lowland Kanto Plain. The bottom depth of slab SG is approximately 120 km near 36.5N and 139.0E, being the same as the surface depth of the PC slab there. Below the Sagami Trough axis near 34.5N and 140.0E, the lowest portion of slab SG is located at a depth of 80 to 90 km. The western bottom end zone of slab SG generally strikes in the NNW-SSE direction, being approximately parallel to the volcanic front.We suggest four basic morphology models of slab SG as follows. (1) Slab SG consists of both the PH slab at a shallower depth and a deeper underlain slab (slab SL). (2) A bookshelf-like configuration of northwardly inclined multi-slabs on the PC slab due to the intermittent southward shift of accumulation sites of short slab tips with episodic subduction at just south of the previously active paleo-Sagami Trough (s). We emphasize that the above evolutional bookshelf model is, to some extent, similar to the sediment layer accretion process near the deep trench system, but the dynamic situation is not the same. (3) A structure combining models (1) and (2). (4) Slab SG is merely the eastern part, having been cooled by the downgoing PC slab, of 65-70 km thick lithosphere of the Izu Outer Block (JOB) without any other slab components.To clarify the structure of the SG slab in more detail, we should incorporate high-gain seismic data from the on-line operating dense seismic observation network deployed at both marine and land areas covering the metropolitan area. In addition, we must study the effects of 3D mantle wedge circulation with dehydration process due to the subduction of both PC and PH slabs from different directions, as well as the space-time evolution history of accretion tectonics at the northern end zone of the Philippine sea plate.

著者

瀬野 徹三

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.116, no.3-4, pp.370-379, 2007-08-25 (Released:2009-11-12)

参考文献数

27

被引用文献数

2 2

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I discuss the danger of earthquakes occurring directly beneath the metropolitan area from temporal and geographical viewpoints. Temporally, large (M>7) earthquakes in Kanto occur 70 years before and a few years after great interplate Kanto earthquakes. The recurrence times of such great earthquakes are more than 220 years. Because 80 years have passed since the last one, at least60 years remain before reaching the active period. It is not legitimate to calculate the probability of large earthquakes occurring in the near future, using the rate of occurrence during the active period before a great earthquake. From a geographical viewpoint, S. Kanto is located in the outer zone south of the Median Tectonic Line, where few active faults are distributed. However, in S. Kanto, exceptionally, the Tachikawa fault and the 1855 Ansei-Edo earthquake are located in the outer zone. This zone is specified by a low-velocity zone in the mantle wedge of the upper plate. Dehydration from the subducting slab may weaken the upper plate in this zone, producing anomalous intraplate earthquakes. The upper crust above this low-velocity area should be marked especially as an area having a potential for large earthquakes in the future. The probability of M7 earthquakes being generated at the interface between the Philippine Sea and the upper plates is small. Temporally, the danger of large earthquakes occurring in the near future beneath the metropolitan area does not seem to be large.

著者

米地 文夫

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.97, no.4, pp.317-325, 1988

被引用文献数

5 2

著者

橋本 徹夫 菊地 正幸

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.111, no.1, pp.118-125, 2002-02-25 (Released:2009-11-12)

参考文献数

17

被引用文献数

1 1

---

Subevents of the 1946 Nankai earthquake (Mjma8.0) were distinguished from seismograms recorded on smoked papers with strong motion seismograms (T0=6s, amplification=2) and seismological data of Japan Meteorological Agency. Location and origin time of each subevent were roughly estimated from a hypocenter determination with phase readings of P and S waves for the subevent. Rupture of the Nankai earthquake started at a point southward about 50km off Cape Shionomisaki (first subevent). The rupture propagated in the NNW direction with a rupture velocity of 1.9 km/s and a second subevent that grew to class M8 started after about 16 sec from the initiation of the first subevent. Then the rupture propagated westward, and third subevent of M8 occurred around Tosa Bay, located about 200 km from the second event, about 53 sec after the initiation of the second event. Seismic waves were excited near Tosa Bay during the 1946 Nankai earthquake.

著者

橋本 亘

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.74, no.6, pp.295-316, 1965-12-25 (Released:2009-11-12)

参考文献数

159

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.21, no.10, pp.723b-724, 1909

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.31, no.2, pp.143a-144, 1919