Two‐dimensional viscosity structure of the northeastern Japan islands arc‐trench system

Muto, Jun; Shibazaki, Bunichiro; Ito, Yoshihiro; Iinuma, Toshitaka; Ohzono, Mako; Matsumoto, Takumi; Okada, Tomomi

doi:10.1002/grl.50906

Cited by 28 publications

(30 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…As the future study, a quantitative analysis of time lag values would be important, because the magnitude of stress might be related to the magnitude of the time delay of shear wave splitting. To explain the phenomenon quantitatively, a more realistic calculation with heterogeneous rheological structures would also be necessary [Muto et al, 2013]. The noteworthy observed result of this study is that a trench-parallel fast-polarization direction appeared in the forearc region of the island arc, which can be explained by the two-dimensional finite element model.…”

Section: Resultsmentioning

confidence: 99%

Trench-parallel crustal anisotropy along the trench in the fore-arc region of Japan

Iidaka

Muto

Obara

et al. 2014

Geophys. Res. Lett.

Self Cite

View full text Add to dashboard Cite

In northeastern Japan, the Pacific plate is descending beneath the North American plate. It is generally understood that trench-normal principal stress is dominant in the crust along the Japanese island arc, because the stress field is controlled by the force of the subducting slab. Observations of shear wave splitting using crustal earthquakes reveal a marked lateral variation in fast-polarization direction with distance from the trench. Trench-normal and trench-parallel fast-polarization directions are observed on the back-arc and fore-arc sides, respectively. In this study, two-dimensional finite element modeling with subducting slab was conducted to investigate the interseismic stress field during earthquake cycles, taking into account linear viscoelasticity. In the model, trench-normal compression is found to dominate in the island arc region. However, an extensional field appears in the shallow upper crust of the fore-arc region during earthquake cycles. The trench-parallel crustal anisotropy can be explained by this extensional field.

show abstract

Section: Resultsmentioning

confidence: 99%

Trench-parallel crustal anisotropy along the trench in the fore-arc region of Japan

Iidaka

Muto

Obara

et al. 2014

Geophys. Res. Lett.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Our preferred elastic thickness is smaller than 62 km fixed (not adjusted) by Kogan et al . [, ] for their GPS analysis and rather consistent with the oceanic lithosphere thickness (30–40 km) from the flexural analysis of the bathymetry around the Kuril trench [ Hanks , ] and with the numerical modeling beneath adjacent northeastern Japan [ Muto et al ., ; Hu et al ., ].…”

Section: Discussionmentioning

confidence: 99%

Postseismic gravity change after the 2006–2007 great earthquake doublet and constraints on the asthenosphere structure in the central Kuril Islands

Han

Sauber

Pollitz

2016

Geophysical Research Letters

View full text Add to dashboard Cite

Large earthquakes often trigger viscoelastic adjustment for years to decades depending on the rheological properties and the nature and spatial extent of coseismic stress. The 2006 Mw8.3 thrust and 2007 Mw8.1 normal fault earthquakes of the central Kuril Islands resulted in significant postseismic gravity change in Gravity Recovery and Climate Experiment (GRACE) but without a discernible coseismic gravity change. The gravity increase of ~4 μGal, observed consistently from various GRACE solutions around the epicentral area during 2007–2015, is interpreted as resulting from gradual seafloor uplift by ~6 cm produced by postseismic relaxation. The GRACE data are best fit with a model of 25–35 km for the elastic thickness and ~1018 Pa s for the Maxwell viscosity of the asthenosphere. The large measurable postseismic gravity change (greater than coseismic change) emphasizes the importance of viscoelastic relaxation in understanding tectonic deformation and fault‐locking scenarios in the Kuril subduction zone.

show abstract

“…Based on heat flow data (e.g., Cho and Kuwahara, 2013), seismic tomography, and magnetotelluric measurements, Muto (2011) and Muto et al (2013) estimated the viscosity of the lower crust beneath the arc in NE Japan to be as low as 10…”

Section: Weakened Zone Beneath Volcanic Arcmentioning

confidence: 99%

“…These fluids weaken the overriding plate and may cause partial melting (e.g., Saffer and Bekins, 1999;van Keken et al, 2002). Through modeling heat flow, seismic tomography, and magnetotelluric data, Muto (2011) and Muto et al (2013) have proposed that viscosities of the lower crust below the arc in NE Japan are several orders of magnitude lower than in the surrounding crust. After examining interseismic strain anomalies and the coseismic deformation of the 2011 earthquake in NE Japan, Ohzono et al (2012b) proposed a weak zone below the tens of kilometers wide Ou-backbone range, in the vicinity of the arc.…”

Section: Introductionmentioning

confidence: 99%

Contributions of poroelastic rebound and a weak volcanic arc to the postseismic deformation of the 2011 Tohoku earthquake

Bürgmann

Freymueller

et al. 2014

Earth Planet Sp

View full text Add to dashboard Cite

A better understanding of fluid-related processes such as poroelastic rebound of the upper crust and weakening of the lower crust beneath the volcanic arc helps better understand and correctly interpret the heterogeneity of postseismic deformation following great subduction zone earthquakes. The postseismic deformation following the 2011 M w 9.0 Tohoku earthquake, recorded with unprecedented high resolution in space and time, provides a unique opportunity to study these 'second-order' subduction zone processes. We use a three-dimensional viscoelastic finite element model to study the effects of fluid-related processes on the postseismic deformation. A poroelastic rebound (PE) model alone with fluid flow in response to coseismic pressure changes down to 6 and 16 km in the continental and oceanic crusts, respectively, predicts 0 to 6 cm uplift on land, up to approximately 20 cm uplift above the peak rupture area, and up to approximately 15 cm subsidence elsewhere offshore. PE produces up to approximately 30 cm of horizontal motions in the rupture area but less than 2 cm horizontal displacements on land. Effects of a weak zone beneath the arc depend on its plan-view width and vertical viscosity profile. Our preferred model of the weak sub-arc zone indicates that in the first 2 years after the 2011 earthquake, the weak zone contributes to the surface deformation on land on the order of up to 20 cm in both horizontal and vertical directions. The weak-zone model helps eliminate the remaining systematic misfit of the viscoelastic model of upper mantle relaxation and afterslip of the megathrust.

show abstract

Two‐dimensional viscosity structure of the northeastern Japan islands arc‐trench system

Cited by 28 publications

References 34 publications

Trench-parallel crustal anisotropy along the trench in the fore-arc region of Japan

Trench-parallel crustal anisotropy along the trench in the fore-arc region of Japan

Postseismic gravity change after the 2006–2007 great earthquake doublet and constraints on the asthenosphere structure in the central Kuril Islands

Contributions of poroelastic rebound and a weak volcanic arc to the postseismic deformation of the 2011 Tohoku earthquake

Contact Info

Product

Resources

About