The Fingerprints of Flexure in Slab Seismicity

Sandiford，D.1,2,3; Moresi，L. M.2,4; Sandiford，M.2; Farrington，R.2; Yang，T.5

2020-08-01

10.1029/2019TC005894

TECTONICS   影响因子和分区

0278-7407

1944-9194

Earthquake moment tensors in eastern Pacific (ePac) slabs typically show downdip tensional (DT) axes, whereas in the western Pacific (wPac), they typically show downdip compressional (DC) axes or have mixed orientations indicative of unbending. Prevailing conceptual models emphasize uniform stress/deformation modes, that is, bulk slab stretching or shortening, as the dominant control on intermediate depth seismic expression. In contrast, we propose that a diversity of seismic expression, including DT- and DC-dominated regions, is consistent with expectations of flexural strain accumulation, based on systemic differences in slab geometry. Our analysis reveals two largely unrecognized features of ePac intraslab seismicity. First, earthquake clusters consistent with slab unbending are present in ePac slabs, albeit at much shallower depths than typical of wPac slabs. Second, intermediate depth ePac DT seismicity is strongly localized to the upper half of zones undergoing curvature increase, such as flat slab segments. Our study highlights how the seismic expression of slab flexure is impacted by the relative contribution of brittle and ductile deformation. The strongly asymmetric temperature structure that is preserved in sinking slabs means that seismicity disproportionately records the deformation regime in the colder part of the slab, above the neutral plane of bending. The expression of in-plane stress may be discernible in terms of a systematic modifying effect on the seismic expression of flexure.

earthquakes seismicity slabs subduction

SCI ; EI

英语

其他

Australian Research Council[DP150102887]

Geochemistry & Geophysics

Geochemistry & Geophysics

WOS:000567319100007

AMER GEOPHYSICAL UNION

20203509108862

Deformation

Seismology:484

GEOSCIENCES

2-s2.0-85089829634

Scopus

1.Institute of Marine and Antarctic Studies,University of Tasmania,Hobart,Australia
2.School of Earth Sciences,University of Melbourne,Melbourne,Australia
3.Helmholtz Centre Potsdam - German Research Centre for Geosciences (GFZ),Potsdam,Germany
4.Research School of Earth Sciences,Australian National University,Canberra,Australia
5.Department of Earth and Space Sciences,Southern University of Science and Technology,Shenzhen,China

Sandiford，D.,Moresi，L. M.,Sandiford，M.,et al. The Fingerprints of Flexure in Slab Seismicity[J]. TECTONICS,2020,39(8).

Sandiford，D.,Moresi，L. M.,Sandiford，M.,Farrington，R.,&Yang，T..(2020).The Fingerprints of Flexure in Slab Seismicity.TECTONICS,39(8).

Sandiford，D.,et al."The Fingerprints of Flexure in Slab Seismicity".TECTONICS 39.8(2020).