Tsunami Resonance and Spatial Pattern of Natural Oscillation Modes With Multiple Resonators

Abstract

Tsunami resonance and coupled oscillation of shelf and bays modes has been reported to be important in tsunami wave amplification. The main objective of this work is to study the spatial pattern of natural oscillation modes and to analyze the influence of several resonators on the coast of the central Chile, which has a complex morphology with several bays, submarine canyons, and a wide continental shelf. First, natural oscillation modes were computed by means of modal analysis of local and regional domains. Second, a dense network of tide gauges and pressure sensors was analyzed to obtain background spectra inside bays. Third, tsunami spectra were computed from both tsunami records and numerical simulations. The results show that the use of modal analysis and background and tsunami spectra is effective for identifying natural oscillation modes. In addition, a dense network of tide gauges is useful to validate the spatial pattern of these natural modes. It was observed that larger resonators and the shelf are important in coupling oscillation with local bays, such that large amplification can be observed. Finally, this analysis allowed the diverse effects of 2010 and 2011 tsunamis in the bays of central Chile to be explained, making it possible to better address tsunami mitigation measures and the preparedness of coastal communities.

Tsunami detection by GPS-derived ionospheric total electron content

“…The sea-level records of the 2014 Pisagua and the 2015 Illapel earthquakes were extracted from the coastal tide-gauge network [ http://www.ioc-sealevelmonitoring.org ]. The tsunami records were processed through a zero-phase digital high-pass filter to eliminate signals over a 3-h period to filter out tidal variations 76 . This value is selected based on the results of Bai et al 77 , thus only shelf and bay modes may be identified.…”

Probabilistic tsunami forecasting for early warning

“…For the much smaller Mw 6.8 Zemmouri-Boumerdes event in the Mediterranean, we observed an opposite tendency towards underestimation. A possible reason is that, for smaller earthquakes on steeper faults like this, local resonances and amplification play a more important relative role due poorly modelled smaller tsunami wavelengths; for the Mw 8.8 Maule event, shelf and basin resonances occur also at longer periods 101 , but they are well-captured on a 30 arc-sec grid (see Methods).…”

Tsunami Resonance Characterization in Japan Due to Trans‐Pacific Sources: Response on the Bay and Continental Shelf

“…It does not restrict the wavelengths and can produce modes composed of both stationary and progressive waves. For more details about the mathematical principles of this method, refer to the work of Cortés et al (2017) and Aránguiz et al (2019).…”