Coseismic seafloor deformation in the trench region during the Mw8.8 Maule megathrust earthquake

Map of the study area.

Partial map of the study area.

TitleCoseismic seafloor deformation in the trench region during the Mw8.8 Maule megathrust earthquake
Publication TypeJournal Article
Year of Publication2017
AuthorsMaksymowicz A., Chadwell C.D, Ruiz J., Trehu A.M, Contreras-Reyes E., Weinrebe W., Diaz-Naveas J., Gibson J.C, Lonsdale P., Tryon M.D
JournalScientific Reports
Date Published2017/04
Type of ArticleArticle
ISBN Number2045-2322
Accession NumberWOS:000398339700001
Keywordschile earthquake; GPS; inversion; joint; model; mw=8.8; resolution; rupture; slip; tohoku-oki earthquake; tsunami observations

The M-w 8.8 megathrust earthquake that occurred on 27 February 2010 offshore the Maule region of central Chile triggered a destructive tsunami. Whether the earthquake rupture extended to the shallow part of the plate boundary near the trench remains controversial. The up-dip limit of rupture during large subduction zone earthquakes has important implications for tsunami generation and for the rheological behavior of the sedimentary prism in accretionary margins. However, in general, the slip models derived from tsunami wave modeling and seismological data are poorly constrained by direct seafloor geodetic observations. We difference swath bathymetric data acquired across the trench in 2008, 2011 and 2012 and find similar to 3-5 m of uplift of the seafloor landward of the deformation front, at the eastern edge of the trench. Modeling suggests this is compatible with slip extending seaward, at least, to within similar to 6 km of the deformation front. After the M-w 9.0 Tohoku-oki earthquake, this result for the Maule earthquake represents only the second time that repeated bathymetric data has been used to detect the deformation following megathrust earthquakes, providing methodological guidelines for this relatively inexpensive way of obtaining seafloor geodetic data across subduction zone.

Short TitleSci Rep

Due to the high costs of operation, only few stations for seafloor GPS-Acoustic observations can be installed to study large portions of subduction zones. Therefore, the repeating bathymetry method represents a complementary technique to cover large portions of the margin with enough resolution to study the seafloor deformation during the seismic events, at least for large earthquakes. For this reason, our result highlights the importance of systematic acquisition of high-quality bathymetric data along seismic gaps in convergent margins to compare with post-earthquake measurements, in order to have a better understanding of the co-seismic and post-seismic seafloor deformation.

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