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Lineaments and earthquake ruptures on the East Japan megathrust

Lineaments and earthquake ruptures on the East Japan megathrust
Lineaments and earthquake ruptures on the East Japan megathrust
In this paper we describe the earthquake geology of East Japan, based on a seismotectonic analysis of foreshocks and aftershocks for the 2011 Tohoku-oki Great Earthquake. The earthquake geology is defined by three compressional buttresses that are separated by channels dominated by extensional earthquakes. In the 2011 earthquake sequence, most activity occurred in the Tohoku-oki extensional channel. This is bounded by seismotectonic lineaments that run subparallel to the slip direction of thrust-fault earthquakes in the adjacent compressional buttresses, and to the slip direction of landward-dipping normal-fault aftershocks in the subducting Pacific plate. The northern bounding seismotectonic lineament of the Tohoku-oki extensional channel runs WNW-ESE ∼15 km north of the Miyagi Volcanic Lineament. The southern bounding seismotectonic lineament runs ∼20 km to the south of the Fukushima Volcanic Lineament. These lineaments may reflect faults that splay from deeper structures beneath the volcanic lineaments. In any case, the seismotectonic lineaments appear to reflect zones of weakness, and as is the case in any load-bearing architecture, precursor movements on such focusing structures may herald the onset of catastrophic failure. We discovered that two-thirds of all major earthquakes with moment magnitude Mw ≥6.9 in the past 40 years in East Japan began within 15 km of the seaward prolongation of a volcanic lineament, and that motion across the northern seismotectonic lineament reversed its sense in the days prior to the 2011 Great Earthquake, suggesting the onset of yield. We infer that continuous geodetic monitoring across the East Japan lineaments might thus provide useful signals for future hazard assessment.
1941-8264
Lister, Gordon
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Tkalčić, Hrvoje
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Hejrani, Babak
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Koulali, Achraf
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Rohling, Eelco
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Forster, Marnie
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McClusky, Simon
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Lister, Gordon
0e705a24-57f2-4111-af3b-34c003ca0b74
Tkalčić, Hrvoje
b1bfae6a-0729-4bab-8a71-16a044fa1c95
Hejrani, Babak
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Koulali, Achraf
92424b25-4a72-4439-ae25-d27331422c5c
Rohling, Eelco
a2a27ef2-fcce-4c71-907b-e692b5ecc685
Forster, Marnie
c1133245-8caf-4424-8dbb-c4b43ccaa626
McClusky, Simon
f1568e57-58d7-4fb8-9a9b-67961351d444

Lister, Gordon, Tkalčić, Hrvoje, Hejrani, Babak, Koulali, Achraf, Rohling, Eelco, Forster, Marnie and McClusky, Simon (2018) Lineaments and earthquake ruptures on the East Japan megathrust. Lithosphere. (doi:10.1130/L687.1).

Record type: Article

Abstract

In this paper we describe the earthquake geology of East Japan, based on a seismotectonic analysis of foreshocks and aftershocks for the 2011 Tohoku-oki Great Earthquake. The earthquake geology is defined by three compressional buttresses that are separated by channels dominated by extensional earthquakes. In the 2011 earthquake sequence, most activity occurred in the Tohoku-oki extensional channel. This is bounded by seismotectonic lineaments that run subparallel to the slip direction of thrust-fault earthquakes in the adjacent compressional buttresses, and to the slip direction of landward-dipping normal-fault aftershocks in the subducting Pacific plate. The northern bounding seismotectonic lineament of the Tohoku-oki extensional channel runs WNW-ESE ∼15 km north of the Miyagi Volcanic Lineament. The southern bounding seismotectonic lineament runs ∼20 km to the south of the Fukushima Volcanic Lineament. These lineaments may reflect faults that splay from deeper structures beneath the volcanic lineaments. In any case, the seismotectonic lineaments appear to reflect zones of weakness, and as is the case in any load-bearing architecture, precursor movements on such focusing structures may herald the onset of catastrophic failure. We discovered that two-thirds of all major earthquakes with moment magnitude Mw ≥6.9 in the past 40 years in East Japan began within 15 km of the seaward prolongation of a volcanic lineament, and that motion across the northern seismotectonic lineament reversed its sense in the days prior to the 2011 Great Earthquake, suggesting the onset of yield. We infer that continuous geodetic monitoring across the East Japan lineaments might thus provide useful signals for future hazard assessment.

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Accepted/In Press date: 3 April 2018
e-pub ahead of print date: 18 April 2018
Published date: 18 April 2018

Identifiers

Local EPrints ID: 419984
URI: http://eprints.soton.ac.uk/id/eprint/419984
ISSN: 1941-8264
PURE UUID: b9456f29-9312-47be-a710-5731808d2cbe
ORCID for Eelco Rohling: ORCID iD orcid.org/0000-0001-5349-2158

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Date deposited: 25 Apr 2018 16:30
Last modified: 28 Jan 2022 02:34

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Contributors

Author: Gordon Lister
Author: Hrvoje Tkalčić
Author: Babak Hejrani
Author: Achraf Koulali
Author: Eelco Rohling ORCID iD
Author: Marnie Forster
Author: Simon McClusky

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