| Title | Compliant volcanic arc and backarc crust in southern Kurile suggested by interseismic geodetic deformation |
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| Author | Itoh, Y; Wang, K ;
Nishimura, T; He, J |
| Source | Geophysical Research Letters vol. 46, issue 21, 2019 p. 11790-11798, https://doi.org/10.1029/2019GL084656 |
| Image |  |
| Year | 2019 |
| Alt Series | Natural Resources Canada, Contribution Series 20190304 |
| Publisher | American Geophysical Union |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf; html |
| Province | Offshore region |
| Area | Hokkaido; Pacific Ocean; Kurile Trench; Japan |
| Lat/Long WENS | 139.0000 150.0000 46.0000 40.0000 |
| Subjects | tectonics; geophysics; Science and Technology; Nature and Environment; satellite geodesy; plate tectonics; subduction zones; deformation; models; crustal models; thermal analyses; seismology; seismic
waves; lithosphere; crustal thickness; seismicity; seismic risk; earthquakes; earthquake risk; geodynamics; global navigation satellite systems (GNSS); Global positioning systems |
| Illustrations | location maps; geoscientific sketch maps; schematic cross-sections; plots |
| Program | Public Safety Geoscience Assessing Earthquake Geohazards |
| Released | 2019 10 16 |
| Abstract | In southern Kurile, interseismic contraction observed with Global Navigation Satellite Systems is faster in the volcanic arc than in the forearc. Here, we use a viscoelastic finite element model to
investigate the physical process responsible for the localized deformation. On the basis of thermal and seismic observations that suggest the volcanic arc and backarc to be more compliant than a typical continental lithosphere, we assume a lower
rigidity and/or smaller thickness for the arc and backarc. We find that the interseismic observations require the volcanic arc to be very compliant and the backarc to be moderately compliant. The trade-off between lower rigidity and smaller thickness
cannot be resolved by interseismic observations alone, but coseismic observations can help to set a lower limit for the rigidity. Our results indicate that properly accounting for the long-wavelength lithospheric heterogeneity is important to
accurately inferring megathrust locking state from geodetic observations. |
| Summary | (Plain Language Summary, not published)
When the megathrust of a subduction zone is locked, the neighboring crust is shortened like a spring to build up energy for future earthquakes. GPS
monitoring of the rate of shortening helps us identify the locked zone. In Hokkaido, however, the rate of shortening is larger in the area hosting a chain of volcanoes, called the volcanic arc. To explain what amplifies the shortening rate, we use
computer models to investigate the effect of the lateral variations in the properties of the crust. We find that the faster shortening occurs because the arc area, and to a lesser degree the area farther away from the trench, is more compliant, that
is, it offers less resistance to the lateral compression due to megathrust locking. The greater compliance is consistent with what can be inferred from heat flow and seismic imaging in this area. Our results indicate that, in order to accurately
infer megathrust locking from GPS observations, we must include the greater compliance in our model. |
| GEOSCAN ID | 315656 |
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