Crustal structure in Izu Peninsula, central Japan, as derived from explosion seismic observations 2. Ito-Matsuzaki profile.

Yoshii, Toshikatsu; Asano, Shûzô; Kubota, Susumu; Sasaki, Yoshimi; Okada, Hiroshi; Masuda, Tetsu; Moriya, Toshio; Murakami, Hiroshi

doi:10.4294/jpe1952.33.435

Cited by 21 publications

(12 citation statements)

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“…Our analysis, however, has indicated that the higher density, 2.3 g/cm3 for example, gives a better correlation between Bouguer anomalies and the structure (YOSHII et al, 1985). This result indicates that assumption of the reduction density of 2.0 g/cm3 seems quite questionable, at least for a structural analysis.…”

Section: Geophysical and Geological Implicationscontrasting

confidence: 43%

“…YOSHII et al (1985) have suggested a possibility that this corresponds to the Nishina Formation, at least in the southwestern part of the peninsula. The Nishina Formation is composed of pyroxine andesite and breccia of the lower Miocene, and it is postulated to be the lower part of the Yugashima Group by KOYAMA and NIITSUMA (1980).…”

Section: Geophysical and Geological Implicationsmentioning

confidence: 99%

“…ASANO et al (1982) and YOSHII et al (1985) constructed cross sections of microearthquakes, crustal movement and Bouguer anomalies along our profile, and compared them with the crustal structure.…”

Section: Geophysical and Geological Implicationsmentioning

confidence: 99%

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Detailed Crustal Structure in the Izu Peninsula as Revealed by Explosion Seismic Experiments

et al. 1986

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Under the Fourth Earthquake Prediction Project of Japan starting from 1979, the Research Group for Explosion Seismology conducted a series of explosion seismic experiments to reveal detailed structure of the shallow crust. In this paper, results from two experiments in the Izu Peninsula are shown. Structure of the shallow crust in the peninsula is very complex and is quite valuable for the other geophysical and geological investigations. For example, time terms of the basement layer show a good correlation with Bouguer anomalies when we assume a reduction density of about 2.7 g/cm3. A layer with a velocity of about 4.1 km/s observed in the whole Izu Peninsula may correspond to the Yugashima Group. Our structural models are also useful for discussion of abnormal crustal uplift and seismic activities observed around the Izu Peninsula in recent years. We believe that the middle-size seismic experiment like these Izu experiments may be the most appropriate one in geologically complex regions such as Japan.

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Section: Geophysical and Geological Implicationscontrasting

confidence: 43%

Section: Geophysical and Geological Implicationsmentioning

confidence: 99%

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Detailed Crustal Structure in the Izu Peninsula as Revealed by Explosion Seismic Experiments

et al. 1986

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“…The Model 1 has a thin and low-velocity layer on the top of the structure, while the Model 2 does not have it as.shown in Table 1. These structures are estimated by trial and error, referring to VP (Yoshii et al, 1985), VS (Kudo et al, 1978), and VP/VS (Goto et al, 1991), so as to fit theoretical dispersion curves well to the observed data. 10 indicates the theoretical amplitude distribution of Rayleigh waves with depth for the Model 1 and Model 2, respectively.…”

Section: Introductionmentioning

confidence: 99%

Waveform Analysis of Volcanic Tremors Associated with the July 1989 Volcanic Activity off the East Coast of Izu Peninsula.

Hashimoto¹,

Maeda²,

Odaka³

et al. 1991

J,Phys,Earth

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Volcanic tremors have occurred since July 11, 1989, off the east coast of Izu Peninsula, and submarine eruptions were visually observed on July 13, 1989. Characteristic tremor (isolated events) occurred after very large amplitude tremors (main phase), which were associated with the submarine eruptions. The isolated events are analyzed instead of the main phase, since they have similar waveforms and spectral shapes (broad peaks at 0.4-0.8Hz). The main phase tremors consist of a succession of events similar to the isolated events. It was found that the radial and vertical components of the main phase and isolated events are those of Rayleigh-type surface waves and the transverse components are Love-type waves. Group velocity analysis reveals that a very thin and low-velocity layer (VS=0.6km/s, thickness=0.1km) exists on the top of the underground structure between the source and the station.Inversion is made for revealing the source mechanism of the isolated events. The result suggests that the source mechanism is an anisotropic explosive type and the source time function is the delta type with the duration time of 2s.

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“…Along the line from Matsuzaki to Ito (Fig. 1, M-I line), Yoshii et al (1985) surveyed the crustal structure by seismic refraction. The line ITO-89B is located close to and almost parallel to the M-I line.…”

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confidence: 99%

Reflection Profiles of the Active Seismic and Volcanic Region off the East Coast of Izu Peninsula.

et al. 1991

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VIBROSEIS reflection explorations profiled the crustal structure under the east coast of Izu Peninsula where a seabed volcano erupted on July 13, 1989. Profiles along two exploration lines show a common feature that consists of three layers. The uppermost layer is floored with relatively intense reflections from shallow depths within 0.5s of two-way travel time, the next one is rather transparent layer, and the last is the basement ceiled with weaker reflections around 1.0s. The shallower reflectors are seen to be broken here and there. The depth of deeper reflector correctly coinsides with the upper limit of the earthquake swarm which is concentrated to the depth range of 2-4km. It is the most interesting that narrow spot-like high velocity bodies are found in the shallowest crust near the seismic swarm area. We suppose that those bodies may be interpreted as aged magma intrusions, and may create an asperity of the major earthquake of M5.5 prior to the submarine volcanic eruption.

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Crustal structure in Izu Peninsula, central Japan, as derived from explosion seismic observations 2. Ito-Matsuzaki profile.

Cited by 21 publications

References 1 publication

Detailed Crustal Structure in the Izu Peninsula as Revealed by Explosion Seismic Experiments

Detailed Crustal Structure in the Izu Peninsula as Revealed by Explosion Seismic Experiments

Waveform Analysis of Volcanic Tremors Associated with the July 1989 Volcanic Activity off the East Coast of Izu Peninsula.

Reflection Profiles of the Active Seismic and Volcanic Region off the East Coast of Izu Peninsula.

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