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Observed and simulated tsunami inundations due to the 2011 Tohoku‐oki (a) and 869 Jyogan (b) earthquakes in the Sendai plane (Satake et al., 2013). For the simulation the source fault models are the same for both cases but reconstructed near‐shore bathymetry and topography are used for the 869 Jyogan earthquake. Three source‐fault model scenarios are considered including final (composite) slip model (orange), slip only in shallow near‐trench fault area (green), and slip only in the deep area (red). The slip of composite, deep and near‐trench fault areas (the same as Figure 12c) and the region (black rectangle) shown in (a) and (b) are shown in (c). The inundation area is defined as the land areas where the modeled flow depth is >0.5 m. Note the simulated inundation areas for the deep and composite models are almost identical. The observed inundation from the 2011 Tohoku‐oki earthquake is shown by blue lines in (a) (Nakajima & Koarai, 2011) and by blue dashed lines in (b) for reference. The locations of certain and possible 869 tsunami deposits (Sawai, 2007; Sawai et al., 2012, 2008) are shown by red and brown circles, respectively. (d) Example of the tsunami deposits at Arahama, located between Natori and Nanakita rivers at Sendai City (a), (b) (Goto et al., 2011). To‐a:Tephra at 915 AD.
Source publication
The 2011 Mw 9.0 Tohoku‐oki earthquake is one of the world's best‐recorded ruptures. In the aftermath of this devastating event, it is important to learn from the complete record. We describe the state of knowledge of the megathrust earthquake generation process before the earthquake, and what has been learned in the decade since the historic event....
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In this paper, we focus on why intraplate seismic initiation and migration occurs, which has widely been considered to be caused by static stress triggering caused by earthquakes, as well as post-seismic slips. To illustrate the mechanism underlying large earthquakes, in particular the migration caused by two key episodes that occurred after 1500 i...
Citations
... Tsunamis may be catastrophic events that have occurred in various parts of the world (Dunbar and McCullough, 2012), such as the Tohoku-Oki tsunami in Japan in 2011 and the Indian Ocean (Sumatra) tsunami in 2004, which were triggered by large earthquakes (Uchida and Bürgmann, 2021). Similar events have occurred in prehistoric times, leaving behind sedimentary traces. ...
Tsunami deposits provide evidence of historical and prehistorical events. However, their preservation in tropical regions is generally poor. The reasons behind this poor preservation are often linked to a number of environmental and anthropogenic factors. This study is focused on analyzing the environmental factors that impact the preservation and availability of tsunami deposits specifically in tropical regions. These factors predominantly encompass climate-related elements such as consistently high temperatures, rainfall, humidity, as well as specific soil processes, oceanic conditions, and vegetation. We compiled a comprehensive database of scientific publications on tsunami deposits, identifying the geomorphic environments where such deposits are typically preserved , as well as the commonly utilized proxies in studying tsunami deposits across different climatic zones. We propose a model that outlines the environmental factors, processes, and their interrelationships that contribute to the preservation and availability of tsunami deposits in tropical regions. This model may prove valuable in the future identification of tsunami deposits in tropical areas.
... In contrast, seismic activity is notably elevated and more widespread offshore, in particular along the primary thrust region beneath the landward slope of the Japan Trench. Several studies involving seismic, gravity, and residual topography analyses have linked the segmentation of megathrust events to material heterogeneities in the overriding plate (16,17), suggesting a substantial influence of structural heterogeneities on earthquake nucleation and rupture style (18). For instance, Bassett et al. (16) proposed that variations in the forearc lithology of the upper plate played a key role in the along-strike variations in the 2011 Tohoku-oki M9 earthquake slip distribution. ...
... This relatively higher rigidity channel appears to coincide with a region of low seismicity, possibly indicating the control of the upper-plate structure on seismicity patterns. Overall, our results suggest that while geodetic inversions yield consistent estimates of fault slip distributions only on large spatial scales (18), this smoothness does not imply that all information contained in coseismic surface displacements is exploited by standard elastic modeling. Additional insights into Earth's structure and dynamics can be gained by inverting for the medium surrounding the fault. ...
Rock strength has long been linked to lithospheric deformation and seismicity. However, independent constraints on the related elastic heterogeneity are missing, yet could provide key information for solid Earth dynamics. Using coseismic Global Navigation Satellite Systems (GNSS) data for the 2011 M9 Tohoku-oki earthquake in Japan, we apply an inverse method to infer elastic structure and fault slip simultaneously. We find compliant material beneath the volcanic arc and in the mantle wedge within the partial melt generation zone inferred to lie above ~100 km slab depth. We also identify low-rigidity material closer to the trench matching seismicity patterns, likely associated with accretionary wedge structure. Along with traditional seismic and electromagnetic methods, our approach opens up avenues for multiphysics inversions. Those have the potential to advance earthquake and volcano science , and in particular once expanded to InSAR type constraints, may lead to a better understanding of transient lithospheric deformation across scales.
... Our mechanically self-consistent and data-driven 3D models of long-term SSE cycles, megathrust earthquake initiation, and rupture dynamics in the Guerrero Seismic Gap contribute to a better understanding of the earthquake generation process. They can potentially lead to improved time-dependent operational earthquake forecasting (Uchida & Bürgmann, 2021). By incorporating the transient stress evolution of slow-slip before coseismic rupture and asperities in co-seismic friction drop, our models reproduce the kinematic and dynamic characteristics of both aseismic slip and co-seismic rupture and reveal their physical link. ...
Slow slip events (SSEs) have been observed in spatial and temporal proximity to megathrust earthquakes in various subduction zones, including the 2014 Mw 7.3 Guerrero, Mexico earthquake which was preceded by a Mw 7.6 SSE. However, the underlying physics connecting SSEs to earthquakes remains elusive. Here, we link 3D slow‐slip cycle models with dynamic rupture simulations across the geometrically complex flat‐slab Cocos plate boundary. Our physics‐based models reproduce key regional geodetic and teleseismic fault slip observations on timescales from decades to seconds. We find that accelerating SSE fronts transiently increase shear stress at the down‐dip end of the seismogenic zone, modulated by the complex geometry beneath the Guerrero segment. The shear stresses cast by the migrating fronts of the 2014 Mw 7.6 SSE are significantly larger than those during the three previous episodic SSEs that occurred along the same portion of the megathrust. We show that the SSE transient stresses are large enough to nucleate earthquake dynamic rupture and affect rupture dynamics. However, additional frictional asperities in the seismogenic part of the megathrust are required to explain the observed complexities in the coseismic energy release and static surface displacements of the Guerrero earthquake. We conclude that it is crucial to jointly analyze the long‐ and short‐term interactions and complexities of SSEs and megathrust earthquakes across several (a)seismic cycles accounting for megathrust geometry. Our study has important implications for identifying earthquake precursors and understanding the link between transient and sudden megathrust faulting processes.
... This event was the fourth largest earthquake ever recorded, and the rupture itself is the most-studied megathrust rupture event. The regions surrounding this event continue to exhibit enhanced seismicity rates and postseismic deformation over a decade later (1). However, we still lack a critical understanding of the basic physical and chemical processes controlling the occurrence and magnitude of subduction zone earthquakes, and in particular, we do not understand how stress accumulates over the course of the seismic cycle. ...
Knowledge of the state of stress in subducting slabs is essential for understanding their mechanical behavior and the physical processes that generate earthquakes. Here, we develop a framework which uses a high-resolution focal mechanism catalog to determine the change in the position of the neutral plane before and after the M9 Tohoku-oki earthquake to determine that the deviatoric stress within the slab at intermediate depths must be very low (∼1 MPa). We show that by combining the static stress calculated from coseismic slip distributions with the stress orientations before and after the mainshock, we can determine the full deviatoric stress tensor within the subducting slab at intermediate depths. These results preclude earthquake source mechanisms that require large background driving stresses, favoring a mechanically weak subducting slab, thus providing quantitative constraints on the physical processes that generate intermediate-depth earthquakes.
... One possibility to better understand these interactions is to analyze the seismic productivity as a proxy for the slab stress conditions after a megathrust earthquake 14,15 . In that respect, the 2011/3/11 M w 9.0 Tohoku-oki earthquake is an ideal case study, since it is the best-recorded megathrust earthquake of the instrumental period of seismology [16][17][18][19][20][21] , and it occurred within one of the best-monitored regions of the world, Japan. Several studies conducted after the Tohoku-oki earthquake evidenced that large-scale processes active before the earthquake might have played a role in triggering the mainshock 4,9,[22][23][24][25][26][27][28] . ...
Subduction zones are home to the world’s largest and deepest earthquakes. Recently, large-scale interactions between shallow (0-60 km) and intermediate (80-150 km) seismicity have been evidenced during the interseismic period but also before and after megathrust earthquakes along with large-scale changes in surface motion. Large-scale deformation transients following major earthquakes have also been observed possibly due to a post-seismic change in slab pull or to a bending/unbending of the plates, which suggests the existence of interactions between the deep and shallow parts of the slab. In this study, we analyze the spatio-temporal variations of the declustered seismicity in Japan from 2000 to 2011/3/11 and from 2011/3/11 to 2013/3/11. We observe that the background rate of the intermediate to deep (150-450 km) seismicity underwent a deceleration of 55% south of the rupture zone and an acceleration of 30% north of it after the Tohoku-oki earthquake, consistent with the GPS surface displacements. This shows how a megathrust earthquake can affect the stress state of the slab over a 2500 km lateral range and a large depth range, demonstrating that earthquakes interact at a much greater scale than the surrounding rupture zone usually considered.
... Many aftershocks occurred immediately after the mainshock reached as deep as 70 km (Shinohara et al., 2012). In the past decade, several studies have investigated possible changes in the physical properties of the slab before and after the Tohoku earthquake (Uchida & Burgmann, 2021). Some studies focused on seismicity changes in intermediate-depth earthquakes but drew inconsistent conclusions. ...
Plain Language Summary
Intermediate‐depth earthquakes occur at 70–350 km depth below the Earth's surface. Because of the high pressure and temperature at such depths, the physical mechanism of intermediate‐depth earthquakes is still poorly understood. In this study, we try to obtain insights into this problem by investigating the behaviors of intermediate‐depth earthquakes before and after the 2011 magnitude 9 Tohoku earthquake. We build an intermediate‐depth earthquake catalog in Central and Northeastern Japan around the Tohoku earthquake. This new catalog contains six times more earthquakes and is more complete than the standard catalog used in previous studies. After analyzing the earthquakes from the new catalog, we find no significant precursory acceleration of intermediate‐depth earthquake activities prior to the Tohoku earthquake. However, we observe a clear increase in intermediate‐depth earthquake rate following the Tohoku earthquake. We also observe that the aftershock productivity of intermediate‐depth earthquakes increased following the Tohoku earthquake. The subduction slab beneath our studied area is characterized by a double seismic zone, and we find that aftershock productivity in the upper plane of seismicity is higher than that in the lower plane. This phenomenon may be due to differences in the environments or physical mechanisms in the two planes of intermediate‐depth earthquakes.
... More than a decade of extensive research on the 2011 M W 9.1 Tohoku-Oki earthquake and tsunami have revealed a clear picture of the earthquake rupture. >50 m of slip occurred near the trench up dip from hypocenter off Miyagi Prefecture, as resolved by many kinematic slip models using geodetic, seismic, and tsunami data (e.g., Sun et al., 2017;Lay, 2018;Uchida and Bürgmann, 2021; and references therein). More importantly, such large near-trench slip was confirmed by crucial data sets of differential bathymetry data before and after the earthquake (Fujiwara et al., 2011;Kodaira et al., 2012Kodaira et al., , 2020. ...
... More importantly, such large near-trench slip was confirmed by crucial data sets of differential bathymetry data before and after the earthquake (Fujiwara et al., 2011;Kodaira et al., 2012Kodaira et al., , 2020. There seems a consensus about this earthquake that large shallow slip at the trench caused large seafloor uplift that resulted in the devastating tsunami (e. g., Satake et al., 2013;Yamazaki et al., 2018;Lay, 2018;Uchida and Bürgmann, 2021). Large horizontal seafloor displacement of seafloor slopes driven by the large near-trench slip on a shallowly dipping plate interface also contributed significantly to the tsunami generation (e.g., Hooper et al., 2013). ...
... Most slip models based on geodetic and seismic data failed to explain this important observation, shown by MacInnes et al. (2013), Tappin et al. (2014), and Yamazaki et al. (2018) among others, as these models resolved small or little slip north of ~38.5 • N. In order to explain the large tsunami generation north of 39 • N kinematic slip models based on tsunami data require near-trench slip up to 36 m (e.g., Satake et al., 2013;Yamazaki et al., 2018), which, however, violates the differential bathymetry observations in the northern Japan Trench Kodaira et al., 2020;Fujiwara, 2021;Zhang et al., 2023), indicating no large shallow slip near the trench nor large submarine landslides (Tappin et al., 2014). The turbidite data that shows correlation with large shallow slip at trench off Miyagi Prefecture were also not observed north of ~38.7 • N (e.g., Ikehara et al., 2018;Uchida and Bürgmann, 2021), consistent with the differential bathymetry data. The crucial differential bathymetry and turbidite data are summarized in Fig. 1b. ...
... There have been no large subduction earthquakes along the Hikurangi margin in historical times that could guide expected patterns of coastal deformation. At many subduction zones, the spatial pattern of coupled or partially coupled segments corresponds to slip patches in past great earthquakes (e.g., Chlieh et al., 2008;Loveless & Meade, 2011;Perfettini et al., 2010) and therefore persistent coupling may inform future earthquake behavior (e.g., Chlieh et al., 2011;Kaneko et al., 2010;Lay & Nishenko, 2022;Uchida & Bürgmann, 2021;L. Wang et al., 2015). ...
Earthquake‐driven subsidence can cause cascading hazards at the coast by exacerbating relative sea level rise, storm surges, tsunami, and tidal flooding. At Ahuriri Lagoon near Napier, Aotearoa New Zealand, paleoseismic uplift and subsidence are typically attributed to upper plate faults and subduction interface earthquakes, respectively. We test this assumption with elastic dislocation models of upper plate and subduction interface earthquakes informed by historical events, seismic surveys, and modern interface coupling data. We compared our surface deformation results to paleoseismic records preserved at Ahuriri Lagoon, which includes eight rapid subsidence (c. 0.5–1.2 m) and two rapid uplift events over the last c. 7 kyr. Our models demonstrate that offshore upper plate faults could cause subsidence of c. 0.5–1 m at Ahuriri Lagoon at recurrence intervals of c. 2 kyr. A range of subduction interface earthquakes can also produce subsidence at Ahuriri Lagoon, and may explain larger (>1 m) subsidence, but must rupture the currently creeping (i.e., aseismic) portions of the interface. We demonstrate that both upper plate fault and subduction interface earthquakes may have contributed to the Ahuriri Lagoon records, and that interface coupling may be more spatially or temporally heterogeneous than modern geodetic data suggest. Models of sea‐level rise and earthquake multi‐hazards that do not include the effects of upper plate faulting may mischaracterize risk at the coast.
... In contrast, since instrumental recording of earthquakes began, only five giant earthquakes (M > 9) have occurred globally (Bilek and Lay 2018), posing scientific challenges in relating their occurrence and rupture characteristics to long-term evolving subduction zone parameters. Despite these observational limitations, there have been substantial advances in understanding megathrust earthquakes since the early twenty-first century owing to increases in data density and quality from various sources, including historical seismology, seismic and geodetic instrumentation, offshore fault zone drilling, and advanced physics-based numerical modelling (e.g., Nakamura et al., 2015;Bilek and Lay, 2018;Kioka et al., 2019b;Brodsky et al., 2020;Kodaira et al., 2020Kodaira et al., , 2021Uchida and Bürgmann 2021;Wirth et al., 2022). ...
... However, slip on the F1 fault plane is much weak and even negligible in the F0+F1 model (Fig. S15), indicating the F1 fault is not ruptured in the main shock. The complementary distribution of the postseismic slip area and aftershocks with the coseismic slip area has been observed in many earth- quake cases (Uchida and Bürgmann, 2021;Toda and Stein, 2022). The quick shutdown of aftershock activity on the F0 fault is consistent with the static stress transfer model (Toda and Stein, 2022). ...
