Abstract The deformation transient following large subduction zone earthquakes is thought to originate from the interaction of viscoelastic flow in asthenospheric mantle and slip on megathrust that are both accelerated by sudden coseismic stress change. Here, we show combining insight laboratory solid-state creep friction experiments can successfully explain spatial distribution surface first few years after 2011 M w 9.0 Tohoku-Oki earthquake. reduction effective viscosity resulting...

Deep low‐frequency earthquakes (LFEs) and nonvolcanic tremor have distinctive characteristics unlike those of regular earthquakes, including strong anisotropy in their migration velocity source spectra displaying 1/ f decay. We show that a physical model can explain these features simple framework with slip pulses originating on fault heterogeneity triggered by slow‐slip events. LFE/tremor areas the consist unstable patches sparsely heterogeneously distributed following Gaussian...

[1] Various characteristics have been discovered for small, slow earthquakes occurring along subduction zones, which are deep nonvolcanic tremor, low-frequency (LFEs), and very low frequency (VLFs). In this study, we model these using a dynamic consisting of cluster frictionally unstable patches on stable background. The controlling parameters in our related to the patch distribution viscosity both By decreasing density or increasing viscosity, observed transition rupture propagation...

In order to reproduce slow earthquakes with short duration such as very low frequency events (VLFs) migrating along the trench direction swarms, we apply a 3-D subduction plate boundary model based on slowness law of rate- and state-dependent friction, introducing close-set numerous small asperities (rate-weakening regions) at depth 30 km under high pore pressure condition, in addition large asperity. Our simulation indicates that swarms slip occur repeatedly asperities, these are similar...

We detected long-term hydrostatic pressure changes at ocean-bottom stations of the Dense Oceanfloor Network system for Earthquakes and Tsunamis (DONET) along Nankai trough, off southwestern Japan. these after removing contributions ocean mass variations sensor drift from records. In addition, we a decrease in background seismicity rate nearby earthquake cluster that was synchronous with changes. interpreted observed to reflect vertical deformation floor 3–8 cm, consider cause seafloor...

Abstract We show possible scenarios for the occurrence of M ~ 7 interplate earthquakes prior to and following 9 earthquake along Japan Trench, such as 2011 Tohoku-Oki earthquake. One is so-called Miyagi-ken-Oki earthquake, which we conducted numerical simulations generation cycles by using realistic three-dimensional (3D) geometry subducting Pacific Plate. In a number scenarios, time interval between subsequent was equal or shorter than average recurrence during later stage cycle. The...

We propose a model of numerical simulation for the coexistence afterslip ∼M7 earthquake and slow slip events in Hyuga-nada region Japan that incorporates 3-D geometry Philippine Sea Plate. Coseismic events, recurrence are qualitatively reproduced using composite law, which is type rate- state-dependent friction law with higher cut-off velocity. In addition, characteristic distances area larger than those other seismic source areas. our simulation, afterslip, occurred at velocity-weakening...

In order to understand the characteristics of shallow very low-frequency (VLF) events as revealed by recent ocean-floor observation studies, we perform a trial simulation earthquake cycles in Tonankai district taking 1944 and assuming that slow earthquakes occur on numerous small asperities. Our results show increase moment release rate shallower VLF pre-seismic stage megathrust is higher than deeper events. This may make leveling change due swarms detectable at Dense Oceanfloor Network...

The down-dip limit of the seismogenic zone and up-dip limits deep low-frequency tremors in southwest Japan are clearly imaged by hypocentre distribution. Previous studies using smooth constraints inversion analyses estimated that long-term slow slip events (L-SSEs) beneath Bungo Channel distributed smoothly from part to tremors. Here, we use fused regularisation, a type sparse modelling suitable for detecting discontinuous changes model parameters estimate distribution L-SSEs. largest...

Abstract There are significant differences between the middle and southern segments of Japan Trench in terms seismic aseismic slips on plate interface velocity structures. Although large coseismic slip 2011 Tohoku-Oki earthquake was limited to segment, observed negative residual gravity anomaly area segment corresponds postseismic earthquake. A density distribution model can explain different behaviours two by considering their structural differences. The indicates that south covered with a...

The recent development of a system for exchanging and distributing seismic waveform data over high‐speed networks enables events to be monitored in real time throughout Japan. In the present study, we have developed an automatic real‐time monitoring deep nonvolcanic tremors southwest automatically detects occurrence determines their hypocenters time. addition, creates image files detected tremor activities makes them accessible via World Wide Web. To detect carry out two‐step numerical...

In geodetic data inversion, insufficient observational and smoothness constraints for model parameters make it difficult to clearly resolve small-scale heterogeneous structures with discontinuous boundaries. We therefore developed a novel regularization scheme the inversion problem that uses discontinuity, sparsity, constraints. order assess its usefulness applicability, proposed method was applied synthetic displacements calculated by ring-shaped sharply varying afterslip distribution on...

Abstract The Nankai earthquakes are great interplate with recurrence intervals of 100–200 years, occurring along the Trough, southwestern Japan. New geological evidences suggest that rupture area 1707 earthquake (one largest) extended farther westward than previously thought, and similar magnitude events may have several hundred years. West segments, in Bungo Channel region, slow slip (SSEs) occurred years since 1980. Farther westward, no M ≥ 7.5 except for one 1968 northern Hyuga‐nada near...

To understand the effect of plate coupling on very low-frequency event (VLFE) activity resulting from megathrust earthquakes, we performed long-term multiscale earthquake cycle simulations (including a and slow earthquakes) 3-D subduction boundary model, based rate- state-dependent friction law. Our simulation suggests that quiescence shallow VLFEs off Miyagi may be explained by location in central part 2011 Tohoku because locally strong coupling, while observed activation Iwate (northern...

A snapshot of slip velocity (V) distribution for M8 earthquake occurrence in an generation cycle simulation along the Nankai Trough, off Southwest Japan.Red, yellow, and blue colors indicate high-speed (seismic), moderate-speed (comparable to plate motion = V pl ), slow speed (much slower than motion), respectively. EARTHQUAKE GENER ATION MODEL FOR PL ATE BOUNDARIESEarthquake can be represented a model as repetitive sequence stick-slip events on interface.The coupled zone is loaded by...

Abstract We consider a Bayesian multi‐model fault slip estimation (BMMFSE), which incorporates many candidates of the underground structure (Earth and plate boundary geometry) model characterized by prior probability density function (PDF). The technique is used to study long‐term slow events (L‐SSEs) that occurred beneath Bungo Channel, southwest Japan, in around 2010 2018. here focus on two advantages BMMFSE: First, it allows for estimating distribution without introducing relatively...

Abstract The 2011 Tohoku-Oki great earthquake increased the difficulty of evaluating long-term probability seismic activity along Japan Trench because unknown impact unprecedentedly large slip. In this study, “Miyagi-ken-Oki earthquakes”, an M > 7 sequence off Miyagi Prefecture, located at edge source area was simulated. We conducted numerical simulations generation cycles based on rate- and state-dependent friction law representing stress accumulation release process plate interface....

The deformation transient that follows large subduction zone earthquakes is thought to originate from the interaction of viscoelastic flow in asthenospheric mantle and slip on megathrust are both accelerated by sudden coseismic stress change. surface following 2011 Mw 9.0 Tohoku earthquake provides some most comprehensive constraints mega-quakes. Assuming rocks Newtonian, low viscosity required explain was attributed a weak lithosphere-asthenosphere boundary, but these findings at odds with...

In geodetic data inversion, insufficient observational and smoothness constraints for model parameters make it difficult to clearly resolve small-scale heterogeneous structures with discontinuous boundaries. We therefore applied sparse modelling inversion. this paper, we reported two examples; one is developed a novel regularization scheme the inversion problem that uses discontinuity, sparsity, constraints. order assess its usefulness applicability, proposed method was synthetic...

To estimate seismic plate coupling and crustal deformation near the trench such as Nankai Trough, we perform a trial simulation of earthquake, applying rate- state dependent friction law on boundary assuming megathrust earthquake slow earthquakes occurring in numerous small asperities. Our suggests that observed activity shallow locally around fault segmentation between source regions Tonankai may be due to weak two segments, while quiescence Tokai indicate strong segments. evaluate these...