Geomorpholgy, geology and subsurface structure of the Median Tectonic Line active fault zone in the central part of Shikoku

篤正, 岡田; 信彦, 杉戸

doi:10.5575/geosoc.112.s117

Cited by 2 publications

(1 citation statement)

References 37 publications

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“…The 1596 Keicho earthquake, which is known from historical accounts, is probably the most recent seismic rupture event along the MTLFZ. This date is consistent with the age of the latest event estimated on the basis of geological evidence obtained by trenching studies (Goto et al, ; Headquarters for Earthquake Research Promotion (HERP), ; Okada, ; Okada & Sugito, ; Tsutsumi et al, ; Yeats, ). Both documentary and geological evidence suggest that a series of earthquakes with M ≥ 7 occurred in 1596 over a distance of at least 300 km along the MTLFZ.…”

Section: Introductionsupporting

confidence: 87%

The 1596 Keicho Earthquake, a 5‐Day, 300‐km‐Long Sequential Rupture Event in the Median Tectonic Line Fault Zone, Southwestern Japan

et al. 2019

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Historical accounts and geological surveys suggest that a sequential rupture event occurred in 1596 CE in the Median Tectonic Line fault zone (MTLFZ) in southwestern Japan. During this event, known as the 1596 Keicho earthquake, the rupture probably propagated in two or three sequential stages, similar to a series of events that occurred along the North Anatolian fault during 1939–1999. The detailed rupture process of the 1596 earthquake event is unknown, however, because coseismic seismological, geological, and geodetic observation data are not available. To reconstruct the rupture processes, we integrated data from Coulomb stress change analyses, fault geometrical analyses, historical accounts, and rupture history. The results suggest that the rupture initiated on the Kawakami fault on 1 September 1596 and propagated bilaterally, to the Beppu Bay fault system, which ruptured on 4 September, and to the MTLFZ in eastern Shikoku and the Rokko‐Awaji fault zone and Arima‐Takatsuki Tectonic Line in the Kinki area, which ruptured on 5 September. However, there is a small possibility that the rupture initiated at the western end of the MTLFZ and propagated eastward unilaterally. The propagation of ruptures might be sensitively controlled not only by stress perturbation and fault geometry but also by rupture history. Evaluation of fault rupture behavior from various viewpoints can contribute to the mitigation of future seismic disasters in fault zones where detailed coseismic observation data from the past are lacking.

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Section: Introductionsupporting

confidence: 87%

The 1596 Keicho Earthquake, a 5‐Day, 300‐km‐Long Sequential Rupture Event in the Median Tectonic Line Fault Zone, Southwestern Japan

et al. 2019

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Seismic-Derived Quality Factor for Lithology Classification around the Median Tectonic Line

Shigei¹,

Tsuji²,

Matsuoka³

et al. 2014

J. Soc. Mat. Sci., Japan

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We calculated quality factor from seismic reflection data in order to classify the lithology around the Median Tectonic Line (MTL). Since seismic velocity around the MTL was not accurately estimated, it was difficult to classify the lithology and characterize the MTL. To calculate quality factor from seismic data, we used two methods: (1) spectral ratio method and (2) peak frequency method. In this study, we applied these two methods for the multi-channel seismic reflection data as well as zero-offset Vertical Seismic Profiling (VSP) data acquired at MTL in Ehime Prefecture, Japan. The result shows that quality factor is significantly changed at the lithological boundary beneath the MTL. From the estimated quality factor, we interpret that lithological boundary beneath the MTL is dipping to north. This study further shows that quality factor can be useful seismic attribute for lithology classification, even when seismic velocity cannot be estimated.

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Geomorpholgy, geology and subsurface structure of the Median Tectonic Line active fault zone in the central part of Shikoku

Cited by 2 publications

References 37 publications

The 1596 Keicho Earthquake, a 5‐Day, 300‐km‐Long Sequential Rupture Event in the Median Tectonic Line Fault Zone, Southwestern Japan

The 1596 Keicho Earthquake, a 5‐Day, 300‐km‐Long Sequential Rupture Event in the Median Tectonic Line Fault Zone, Southwestern Japan

Seismic-Derived Quality Factor for Lithology Classification around the Median Tectonic Line

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