The 11 March 2011 Tohoku tsunami wavefront mapping across offshore Southern California

Abstract

The 11 March 2011 (M w = 9.0) Tohoku tsunami was recorded by a temporary array of seafloor pressure gauges deployed off the coast of Southern California, demonstrating how dense array data can illustrate and empirically validate predictions of linear tsunami wave propagation characteristics. A noise cross-correlation method was used to first correct for the pressure gauge instrument phase response. Phase and group travel times were then measured for the first arrival in the pressure gauge tsunami waveforms filtered in narrow bands around 30 periods between 200 and 3000 s. For each period, phase velocities were estimated across the pressure gauge array based on the phase travel time gradient using eikonal tomography. Clear correlation was observed between the phase velocity and long-wavelength bathymetry variations where fast and slow velocities occurred for deep and shallow water regions, respectively. In particular, velocity gradients are pronounced at the Patton Escarpment and near island plateaus due to the abrupt bathymetry change. In the deep open ocean area, clear phase velocity dispersion is observed. Comparison with numerically calculated tsunami waveforms validates the approach and provides an independent measure of the finite-frequency effect on phase velocities at long periods.

Tsunami data assimilation of Cascadia seafloor pressure gauge records from the 2012 Haida Gwaii earthquake

“…Therefore, only 27 tsunami waveforms at DART and APG stations are used for waveform inversion (Figure b). Because the DPG waveforms are accurate in terms of the tsunami arrival times and wave periods [ Sheehan et al , ; Lin et al , ], we correct the observed amplitudes of 30 DPG records based on tsunami simulations from the source model. This correction makes it possible to use DPG data together with the DART and APG data to fulfill the requirement on the data's spatial coverage for the tsunami data assimilation method.…”

Back‐Projection Imaging of a Tsunami Excitation Area With Ocean‐Bottom Pressure Gauge Array Data

“…These arrays enable us to observe tsunamis propagating across such an array directly. Tsunami recordings by using an OBPG array have been analyzed by various approaches: for example, to estimate tsunami source processes (e.g., Fukao et al., 2018; Hossen et al., 2015; Kubota, Kubo, et al., 2021), to reconstruct tsunami wavefields by data assimilation (e.g., Gusman et al., 2016; Wang & Satake, 2021), to detect scatterers of tsunami waves by the beamforming method (Kohler et al., 2020), and to derive a phase velocity map of tsunamis by the eikonal tomography (Lin et al., 2015).…”

Mechanism of the 2015 volcanic tsunami earthquake near Torishima, Japan

“…S2C), which depends on the frequency and water depth of the reference station (20,21). The frequency-dependent travel time (22)(23)(24) and propagation direction at the reference station are sensitive to the tsunami source location (Fig. 2; see also fig.…”