Tsunami resonance and standing waves in Hangzhou Bay

Earthquakes occurring in the Ryukyu Trench, Nankai Trough, and Japan Trench can trigger tsunamis, affecting Hangzhou Bay, China. The 2011 Tohoku tsunami reached the east China coast and resulted in prolonged oscillations in Hangzhou Bay. We used this event as an example and studied the resonance behavior in Hangzhou Bay by spectral and modal analyses. We simulated the wavefield of the 2011 Tohoku tsunami and validated the modeling results using the tide gauge records. The spectral analysis based on the fast Fourier transform of the entire bay area indicated that the resonance oscillations with periods of 66 and 54min had the highest energy amplification, and the mode of 120min had a large amplitude near Zhenhai and Fengxian. Additionally, we conducted a modal analysis that relied solely on bathymetry data to analyze the eigenmodes of natural oscillations inside the bay. The regional bay-scale oscillations had periods of up to 286min. The energy amplification area was generally consistent with the spectral analysis. These findings have implications for tsunami hazard assessments in coastal communities.

Automated summary

Research shows that earthquakes occurring in the Ryukyu Trench, Nankai Trough, and Japan Trench can trigger tsunamis, affecting Hangzhou Bay in China, especially the prolonged oscillations caused by the 2011 Tohoku tsunami. Spectral and modal analyses revealed that resonant oscillations with longer periods had the highest energy amplification, providing important implications for tsunami hazard assessments in coastal communities.