Surface Fault Ruptures on the Northwest Coast of Awaji Island Associated with the Hyogo-ken Nanbu Earthquake of 1995, Japan

Awata, Yasuo; Mizuno, Kiyohide; Sugiyama, Yuichi; Imura, Ryusuke; Shimokawa, Kuniyasu; Okumura, Koji; Tsukuda, Eikichi; Kimura, Kuniko

doi:10.4294/zisin1948.49.1_113

Cited by 47 publications

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“…After the earthquake, field surveys found that the known Nojima fault on Awaji island had moved right laterally [Awata et al, 1995]. On the contrary, seismic fatfits did not appear on the surface in the Kobe area.…”

mentioning

confidence: 99%

Synthetic aperture radar interferogram of the 1995 Kobe Earthquake and its geodetic inversion

Ozawa¹,

Murakami²,

Fujiwara³

et al. 1997

Geophysical Research Letters

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Since these models estimate only fault slips by assuming the fault locations beforehand, they are not so decisive in locating the earthquake faults in the Kobe area.By using two dimensional geodetic data of the SAR component of reverse dip-slip of about 2 m and strike slip of interferogram, we can further constraint the location of active about2m. In the Kobe area, theamountofsliprangedfrom0.3 fatfits than using conventional geodetic or seismic data. In this to 1.2 m and was small compared with the slip on the Nojima study, we show the detected crustal deformation of this fault. The restfits of these slip vectors agreed well with the earthquake by SAR interferogram and introduce a fault model results of other seismic, geodetic, and field studies.based on all the available geodetic data.

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mentioning

confidence: 99%

Synthetic aperture radar interferogram of the 1995 Kobe Earthquake and its geodetic inversion

Ozawa¹,

Murakami²,

Fujiwara³

et al. 1997

Geophysical Research Letters

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“…The Nojima fault sample was obtained at the site where surface rupture occurred during the 1995 Kobe earthquake [Awata et al, 1996]. No surface rupture occurred along the Kusumoto fault [Awata et al, 1996].…”

Section: Samples and Resultsmentioning

confidence: 99%

Apatite fission‐track dating of fault‐related rocks along the Nojima and Kusumoto faults and its tectonic significance

Ito

2004

Geophysical Research Letters

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[1] The tectonic history of the Nojima fault, a $10 kmlong active fault whose movement caused the disastrous 1995 Kobe earthquake, was studied by the apatite fissiontrack (AFT) dating method. AFT ages of 63 -83 Ma from a thermally undisturbed uplifted block indicate relatively minor uplift since $65 Ma with an estimated total exhumation of $3.6 km assuming a geothermal gradient of 25°C/km. AFT ages of 44-54 Ma and the nature of the track length distribution from fault-related rocks indicate that fault-related hydrothermal minerals, such as laumontite and chlorite, and foliated cataclasite were formed by ancient fault activity that occurred before $44 Ma. It is inferred that the Quaternary fault activity of the Nojima fault is a relatively major phase in the entire tectonic history of the Nojima fault.

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“…6). Although surface rupture was observed on the Nojima Fault in the northwestern part of Awaji Island (Nakata et al, 1995;Awata et al, 1996), most of the aftershocks did not occur directly beneath the Nojima Fault, but along the Higashiura Fault and the Kariya Fault, and around the southern end of the Nojima Fault.…”

Section: Awaji Regionmentioning

confidence: 94%

“…The aftershock region extends about 70 km from northeast to southwest (Hirata et al, 1996;Katao et al, 1997). The surface rupture caused by the mainshock was observed along the Nojima Fault which is located on the northwestern coast of Awaji Island (Nakata et al, 1995;Awata et al, 1996). The observation of microearthquake activity for the past 30 years clearly shows that the seismicity along the mainshock rupture zone was low on the southern side of the Arima-Takatsuki Tectonic Line (ATTL) before the mainshock, while the seismicity has been high in the Tamba Plateau on the northern side of ATTL (Katao et al, 1997;Hiramatsu et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

Spatial distribution of atypical aftershocks of the 1995 Hyogo-ken Nanbu earthquake

2014

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The 1995 Hyogo-ken Nanbu earthquake (M JMA 7.3) occurred on January 17, 1995. To reveal the detailed stress field after the mainshock, we relocate hypocenters of aftershocks (M ≥ 2.3) and determine their focal mechanisms using seismic records obtained by GROUPS-95, a temporary dense seismic network in and around the aftershock region. Along the mainshock rupture zone, some aftershocks are nearly N-S compression or normal fault type events, which is inconsistent with the regional stress field of approximately horizontal E-W compression. We call these aftershocks atypical, defined as events which have focal mechanisms with P-axis directions more than 45• from the regional stress field. The atypical aftershocks amount to about 17% of the total. No temporal variations in aftershock mechanism are found in the analysis period. Their spatial distribution is compared with the slip and stress distribution of the mainshock, as well as the P-and S-wave velocity structure. Most of them are located at the upper boundary between the slipped and unslipped zones of the mainshock. We suggest that the atypical aftershocks are caused by the disturbance of the local tectonic stress field due to the heterogeneous coseismic slip.

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Surface Fault Ruptures on the Northwest Coast of Awaji Island Associated with the Hyogo-ken Nanbu Earthquake of 1995, Japan

Cited by 47 publications

References 0 publications

Synthetic aperture radar interferogram of the 1995 Kobe Earthquake and its geodetic inversion

Synthetic aperture radar interferogram of the 1995 Kobe Earthquake and its geodetic inversion

Apatite fission‐track dating of fault‐related rocks along the Nojima and Kusumoto faults and its tectonic significance

Spatial distribution of atypical aftershocks of the 1995 Hyogo-ken Nanbu earthquake

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