Recent Surface Faulting Events along the Middle Section of the Itoigawa-Shizuoka Tectonic Line

Okumura, Koji; Shimokawa, Kuniyasu; Yamazaki, Haruo; Tsukuda, Eikichi

doi:10.4294/zisin1948.46.4_425

Cited by 28 publications

(19 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…According to geomorphological as well as geological studies, the slip rate of the Gofukuji Fault in the central ISTL is estimated as large as 8.6-9.5 mm/yr with an average earthquake repeat time of about 1,000 years (Ikeda and Yonekura, 1986;Okumura et al, 1994). The East Matsumoto-Basin Fault (hereafter called EMBF) in the northern ISTL is also active, having 3.0 mm/yr slip rate (Okumura et al, 1998).…”

Section: Itoigawa-shizuoka Tectonic Linementioning

confidence: 99%

Crustal deformation around the northern and central Itoigawa-Shizuoka Tectonic Line

et al. 2014

View full text Add to dashboard Cite

We established a dense permanent GPS array around the northern and central Itoigawa-Shizuoka Tectonic Line (ISTL) in order to study loading processes of inland active faults. 1-4 years observation has revealed concentrated deformation (about 0.3 ppm/yr) around the East Matsumoto-Basin Fault, an active fault along the ISTL, consistent with historic triangulation data. The deformation pattern is explained by dislocation models incorporating horizontal detachment fault with steady slip in the upper crust. However, deformation data alone cannot determine the model and there exist different possibilities. The vicinity of the Gofukuji fault is being deformed less in spite of the large long-term slip rate. These observations indicate that the deformation pattern is laterally heterogeneous along the ISTL. The two faults are considered to be loaded by different mechanisms.

show abstract

Section: Itoigawa-shizuoka Tectonic Linementioning

confidence: 99%

Crustal deformation around the northern and central Itoigawa-Shizuoka Tectonic Line

et al. 2014

View full text Add to dashboard Cite

show abstract

“…The ISTL is an active fault system and is recognized as having one of the largest slip rates in the Japanese islands. The slip rate of the Gofukuji Fault, located in the central ISTL, is estimated to be approximately 8.0 mm/yr based on geomorphological and geological studies (Okumura et al, 1994). Across the northern part of the ISTL, GPS measurements indicate horizontal crustal shortening (Sagiya et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

Seismicity of the northern part of the Itoigawa-Shizuoka Tectonic Line

Sakai

2014

Earth Planet Sp

View full text Add to dashboard Cite

The relationship between recent seismicity and the active fault system was investigated using the precise hypocentral distribution by taking into consideration the heterogeneity of the velocity structure around the northern part of the Itoigawa-Shizuoka Tectonic Line (ISTL), the western boundary of the northern Fossa Magna basin. Since a velocity structure suitable for the ISTL is necessary for precise hypocentral determination, deep seismic reflection and refraction profiling were undertaken in 2002 across the northern part of the ISTL and a reliable velocity model was obtained. The hypocenters were located using the station corrections derived from the velocity model. The obtained hypocenters were found to be distributed in a straight line in an almost north-tosouth direction. The hypocenters, whose lower limit was approximately 15 km, were distributed around a vertical plane. The focal mechanism solutions were primarily strike-slip and the direction of their P-axis was NW-SE to WNW-ESE. The fault planes expected from these mechanisms are consistent with the distribution of the hypocenters. However, they are not consistent with the thrust fault planes of previous large earthquakes, which were inferred from the near-surface feature of the active fault system. This suggests that the recent seismicity cannot be attributed to aftershocks of the previous large earthquakes and is not induced by the movement of the active thrust fault.

show abstract

“…The first targets were earthquake faults that ruptured in historical times, i.e., Tanna fault for the 1930 Kita-izu earthquake (The Tanna Fault Trenching Research Group 1984), Senya fault for the 1896 Rikuu earthquake (Research Group for the Senya Fault 1986), Neodani fault for the 1891 Nobi earthquake (Okada et al 1992), and Atotsugawa fault for the 1858 Hietsu earthquake (Okada et al 1989). Attention then turned to active faults that have not ruptured in historical time (e.g., Research Group for the Itoshizu Tectonic Line Active Faults 1988; Suzuki et al 1989;Tsusumi et al 1991;Yamazaki et al 1993;Chida et al 1994;Okumura et al 1994;Toda et al 1994;Watanabe et al 1994) .…”

Section: Excavation Study Of Active Faultsmentioning

confidence: 99%

Tectonic Geomorphological Active Fault Studies in Japan after 1980

Suzuki

2013

Geog. Rev. Japan B

View full text Add to dashboard Cite

Tectonic geomorphology has played important roles in active fault studies in Japan. Following large historical earthquakes, the concept of active fault was formulated and detailed information has rapidly accumulated. This paper reviews the progress of active fault studies in Japan since the 1980s. The period 1980 to 1994 can be regarded as the matured period of active fault studies during seismic calm. The studies conducted during this period are categorized into the following: 1) excavation studies of active faults, 2) analytical studies of tectonic landform evolution based on dislocation models, 3) chronological studies supported by the development of age determination techniques, and 4) studies quantifying the rate of crustal deformation. In 1995, the Great Kobe Earthquake occurred. The earthquake triggered a seismically active period in Japan, and the active fault has become an important issue in disaster mitigation. The research in the decade after 1995 can be summarized as follows: 1) intensive investigations of active faults, 2) detailed large-scale mapping, 3) seismic reflection profiling, 4) long-term forecasts of earthquakes, 5) careful study of flexural deformation, and 6) overseas research on large destructive earthquakes. Then, the period since 2005 has witnessed the rediscovery of active faults, with research considering 1) the relations between the large earthquakes which often occurred in this period and their seismogenic active faults, 2) precise distribution of active faults, 3) the relations between active tectonics and geodetical movement, 4) the relations between interplate earthquakes and submarine active faults, and 5) the difficult problems of prevention against infrequent disasters like the 2011 Great East Japan Earthquake. Additionally, since around 2006, some nuclear power plants have faced problems associated with active faults because some active faults had been overlooked or ignored in the seismic design of these plants. Active fault research now bears greater social responsibility.

show abstract

Recent Surface Faulting Events along the Middle Section of the Itoigawa-Shizuoka Tectonic Line

Cited by 28 publications

References 0 publications

Crustal deformation around the northern and central Itoigawa-Shizuoka Tectonic Line

Crustal deformation around the northern and central Itoigawa-Shizuoka Tectonic Line

Seismicity of the northern part of the Itoigawa-Shizuoka Tectonic Line

Tectonic Geomorphological Active Fault Studies in Japan after 1980

Contact Info

Product

Resources

About