Numerical tsunami simulation including elastic loading and seawater density stratification

Allgeyer, S.; Cummins, Phil R.

doi:10.1002/2014gl059348

Cited by 77 publications

(51 citation statements)

References 24 publications

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“…For the near-field problem, short-period dispersion is most relevant for producing waveform features not captured in numerical modeling. The long-period far-field dispersion has been recognized to delay travel times and responsible for the initial reversed polarity in open ocean tsunami waveforms observed during recent large earthquakes [Tsai et al, 2013;Watada, 2013;Watada et al, 2014;Allgeyer and Cummins, 2014;Yue et al, 2014] but can be ignored here due to small source-to-station distances. Here we characterize the predominant uncertainties in the tsunami propagation modeling as deviations in the frequency dispersion relations (Figures 3a and 3b).…”

Section: Design Of C P For Model Prediction Uncertaintiesmentioning

confidence: 99%

Probabilistic imaging of tsunamigenic seafloor deformation during the 2011 Tohoku‐oki Earthquake

Jiang

Simons

2016

JGR Solid Earth

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Diverse observations from the 2011 Mw 9.0 Tohoku‐oki earthquake pointed to large coseismic fault slip proximal to the Japan Trench. This seismic failure prompted a reevaluation of the conventional view that the outer forearc is generally aseismic. However, the nature of near‐trench fault slip during this event remains debated, without consensus on whether slip peaked at the trench or at greater depths. Here we develop a probabilistic approach to image the spatiotemporal evolution of coseismic seafloor displacement from near‐field tsunami observations. In a Bayesian framework, we sample ensembles of nonlinear source models parameterized to focus on near‐trench features, incorporating the uncertainty in modeling dispersive tsunami waves in addition to nominal observational errors. Our models indicate that seafloor in the region of the earthquake was broadly uplifted and tilted seaward approaching the deep‐ocean trench. Over length scales of ~40 km, seafloor uplift peaks at 5 ± 0.6 m near the inner‐outer forearc transition and decreases to 2 m at the trench axis over a distance of 50 km, corresponding to a seafloor tilt of 0.06 ± 0.02 m/km. Over length scales of ~20 km, peak uplift reaches 7 ± 2 m at the similar location, but uplift at the trench is less constrained. Elastic modeling that reproduces the observed tilt requires a coseismic slip deficit at the trench. Such a deficit is effectively consistent with a metastable frictional model for the shallowest megathrust. While large shallow earthquakes in the region cannot be completely ruled out, aseismic deformation is the most likely mode for satisfying the long‐term slip budget.

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Section: Design Of C P For Model Prediction Uncertaintiesmentioning

confidence: 99%

Probabilistic imaging of tsunamigenic seafloor deformation during the 2011 Tohoku‐oki Earthquake

Jiang

Simons

2016

JGR Solid Earth

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“…However, the observed tsunami arrivals in the far field are significantly delayed relative to the simulated tsunami waveforms [ Rabinovich et al ., ; Allgeyer and Cummins , ; Inazu and Saito , ; Watada et al ., ]. In addition, tsunami forerunners in the far field with a reversed polarity were also reported [ Allgeyer and Cummins , ; Watada et al ., ]. In general, arrival time and initial phase of tsunamis are very important for the tsunami waveform inversion.…”

Section: Introductionmentioning

confidence: 99%

“…For tsunami waveform inversions, the linear shallow water wave, whose velocity solely depends on the bathymetry without dispersion, has been assumed to compute the Green's functions [e.g., Fujii et al, 2011;Fujii and Satake, 2013]. However, the observed tsunami arrivals in the far field are significantly delayed relative to the simulated tsunami waveforms [Rabinovich et al, 2011;Allgeyer and Cummins, 2014;Inazu and Saito, 2013;Watada et al, 2014]. In addition, tsunami forerunners in the far field with a reversed polarity were also reported [Allgeyer and Cummins, 2014;Watada et al, 2014].…”

Section: Introductionmentioning

confidence: 99%

Fault slip distribution of the 2014 Iquique, Chile, earthquake estimated from ocean‐wide tsunami waveforms and GPS data

Gusman

Murotani

Satake

et al. 2015

Geophysical Research Letters

131

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We applied a new method to compute tsunami Green's functions for slip inversion of the 1 April 2014 Iquique earthquake using both near-field and far-field tsunami waveforms. Inclusion of the effects of the elastic loading of seafloor, compressibility of seawater, and the geopotential variation in the computed Green's functions reproduced the tsunami traveltime delay relative to long-wave simulation and allowed us to use far-field records in tsunami waveform inversion. Multiple time window inversion was applied to tsunami waveforms iteratively until the result resembles the stable moment rate function from teleseismic inversion. We also used GPS data for a joint inversion of tsunami waveforms and coseismic crustal deformation. The major slip region with a size of 100 km × 40 km is located downdip the epicenter at depth~28 km, regardless of assumed rupture velocities. The total seismic moment estimated from the slip distribution is 1.24 × 10 21 N m (M w 8.0).

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“…The arrival time and waveform discrepancies between the simulated and observed tsunami waves at far field had been noted for the 1960 Chile tsunami as well as more recent transoceanic tsunamis (e.g., Fujii & Satake, ; Imamura et al, ; Rabinovich et al, ). In recent years, this phenomenon was well explained by the effects of elasticity of the Earth, water compressibility, gravity change by tsunami motion, and ocean stratification (Allgeyer & Cummins, ; Ho et al, ; Tsai et al, ; Watada, ; Watada et al, ). The phase correction method proposed by Watada et al () converts the linear long waves for incompressible water and rigid ocean bottom and time‐constant gravity field into dispersive waveforms for compressible water and deformable ocean bottom and time‐variable gravity field.…”

Section: Introductionmentioning

confidence: 99%

Source Estimate for the 1960 Chile Earthquake From Joint Inversion of Geodetic and Transoceanic Tsunami Data

Satake

Watada

et al. 2019

JGR Solid Earth

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The slip distribution of the 1960 Chile earthquake was estimated using geodetic data, local tsunami data, and newly usable transoceanic tsunami data. The large slips triggered a significant tsunami which was recorded by the tide gauges around the Pacific Ocean. We performed a two‐step inversion to estimate the slip distribution. In the first step, we jointly inverted the tsunami waveforms and local geodetic data to recover the ground and seafloor vertical displacement. The transoceanic tsunami data could not be used for waveform inversions until the wave phase and arrival time discrepancies were recently reconciled by improving the long‐wave theory with the phase correction method. The random arrival time discrepancy due to inaccurate local bathymetry and/or instrumental problems was considered by the optimal time alignment. In the second step, we estimated the slip distribution on the plate interface by inverting the vertical displacement obtained in the first step. Checkerboard tests showed that our method and data can resolve displacement at a spatial resolution of at least ~100 km but cannot estimate the rupture velocity. The result for actual data shows a rupture extended about 800 km with a width of about 150 km and three asperities. The large slips are concentrated in the offshore shallow plate interface. Our results indicate that the central and south patches contribute to the large coastal elevation changes at southern source area and high tsunami waves at far field. The estimated moment ranges 1.3–1.9 × 1023 Nm (Mw 9.3–9.4) for rake angles of 90–140°.

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Numerical tsunami simulation including elastic loading and seawater density stratification

Cited by 77 publications

References 24 publications

Probabilistic imaging of tsunamigenic seafloor deformation during the 2011 Tohoku‐oki Earthquake

Probabilistic imaging of tsunamigenic seafloor deformation during the 2011 Tohoku‐oki Earthquake

Fault slip distribution of the 2014 Iquique, Chile, earthquake estimated from ocean‐wide tsunami waveforms and GPS data

Source Estimate for the 1960 Chile Earthquake From Joint Inversion of Geodetic and Transoceanic Tsunami Data

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