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Refining the 2018 M (sub w) 7.5 Papua New Guinea earthquake fault-slip model using subpixel offset

Jeng-Hann Chong and Mong-Han Huang
Refining the 2018 M (sub w) 7.5 Papua New Guinea earthquake fault-slip model using subpixel offset
Bulletin of the Seismological Society of America (November 2020) 111 (2): 1032-1042

Abstract

The Mw 7.5 earthquake that struck central Papua New Guinea in 2018 was the largest event ever recorded in the region with modern seismic instruments. The ground motions associated with this event also triggered widespread landslides and affected more than 500,000 people. However, due to the absence of a local seismic and Global Positioning System network in the vicinity, the fault location, system, and slip distribution of this earthquake are not well documented. In this study, we use the subpixel offset method on the Copernicus Sentinel-1 Synthetic Aperture Radar (SAR) images to calculate the 3D coseismic displacement of the 2018 Papua New Guinea earthquake. The results show clear fault traces that suggest coseismic slip on the Mubi fault and the Mananda fault that triggered landslides that spread out in a more than 260 km2 region. Finite-source inversions based on the subpixel offset measurements show up to 4.1 and 6.5 m coseismic slip on the Mubi and Mananda faults, respectively. Despite higher data uncertainty ( approximately 0.4-0.8 m) of the subpixel offset data, synthetic resolution tests show resolvable slip above 8 km in depth. The lack of shallower slip on the west side of the Mananda fault could be due to an inflated geothermal gradient near the dormant volcano, Mount Sisa, as a slip barrier. The result of the coulomb stress change suggests possible southeastward slip propagation from the Mananda fault to the Mubi fault. Our work successfully resolves 3D coseismic displacement in highly vegetated terrains and demonstrates the feasibility of using the subpixel offset on SAR images to help our understanding of regional active tectonic systems.


ISSN: 0037-1106
EISSN: 1943-3573
Coden: BSSAAP
Serial Title: Bulletin of the Seismological Society of America
Serial Volume: 111
Serial Issue: 2
Title: Refining the 2018 M (sub w) 7.5 Papua New Guinea earthquake fault-slip model using subpixel offset
Affiliation: University of Maryland, College Park, MD, United States
Pages: 1032-1042
Published: 20201124
Text Language: English
Publisher: Seismological Society of America, Berkeley, CA, United States
References: 28
Accession Number: 2021-006820
Categories: Seismology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables, sketch maps
S06°30'00" - N05°30'00", E142°00'00" - E144°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2021, American Geosciences Institute. Abstract, Copyright, Seismological Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 202105
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