| Title | Role of serpentinized mantle wedge in affecting megathrust seismogenic behavior in the area of the 2010 M=8.8 Maule Earthquake |
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| Author | Wang, K ; Huang,
T; Tilmann, F; Peacock, S M; Lange, D |
| Source | Geophysical Research Letters vol. 47, issue 22, 2020 p. 1-10, https://doi.org/10.1029/2020GL090482  Open Access |
| Image |  |
| Year | 2020 |
| Alt Series | Natural Resources Canada, Contribution Series 20200525 |
| Publisher | Blackwell Publishing Ltd. |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf; html |
| Area | Maule; Chile |
| Lat/Long WENS | -75.0000 -71.3333 -33.1667 -35.0000 |
| Subjects | tectonics; igneous and metamorphic petrology; mineralogy; Science and Technology; Nature and Environment; Health and Safety; earthquakes; aftershocks; seismic risk; seismic velocities; tectonic setting;
subduction zones; fault zones; mantle; thermal analyses; modelling; bedrock geology; lithology; serpentinites; antigorite; chrysotile; lizardite; 2010 M8.8 Maule Earthquake |
| Illustrations | location maps; diagrams; schematic sections |
| Program | Public Safety Geoscience Assessing Earthquake Geohazards |
| Released | 2020 10 26 |
| Abstract | What controls subduction megathrust seismogenesis downdip of the mantle wedge corner (MWC)? We propose that, in the region of the 2010 Mw=8.8 Maule, Chile, earthquake, serpentine minerals derived from
the base of the hydrated mantle wedge exert a dominant control. Based on modeling, we predict that the megathrust fault zone near the MWC contains abundant lizardite/chrysotile-rich serpentinite that transforms to antigorite-rich serpentinite at
greater depths. From the MWC at 32-40 km depth to about 60 km, the predominantly velocity-strengthening megathrust accommodated dynamic propagation of the 2010 rupture but with small slip and negative stress drop. The downdip distribution of
interplate aftershocks exhibits a gap around the MWC that can be explained by the velocity-strengthening behavior of lizardite/chrysotile. Interspersed velocity-weakening and dynamic weakening antigorite-rich patches farther downdip may be
responsible for increased abundance of aftershocks and possibly for some of the high-frequency energy radiation during the 2010 rupture. |
| Summary | (Plain Language Summary, not published)
A subduction megathrust rupture may extend from the trench to beneath populated coastal area. To understand what controls the megathrust seismogenic
behavior of its deeper part, we conduct a case study of the 2010 magnitude 8.8 Maule, Chile, earthquake and its aftershocks. With numerical thermal modeling, we find that the deep seismogenic behavior may be controlled by serpentine materials derived
from the base of the overlying hydrated mantle wedge. The deep part of the megathrust ruptured 'passively' against increasing resistance (negative stress drop). Lower-temperature serpentines lizardite and chrysotile that are known to facilitate
aseismic slip may be responsible for an observed gap in aftershock distribution in the downdip direction. Higher-temperature serpentine antigorite that is known to facilitate seismic slip may be responsible for increased aftershocks farther downdip
and possibly radiation of high-frequency energy during the 2010 Maule earthquake. |
| GEOSCAN ID | 327533 |
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