Meteorological Tsunami Generation Due to Sea‐Surface Pressure Change: Three‐Dimensional Theory and Synthetics of Ocean‐Bottom Pressure Change
Tatsuhiko Saito, Tatsuya Kubota, Naotaka Yamamoto Chikasada, Yuusuke Tanaka, Osamu Sandanbata
Abstract
Abstract Although most tsunamis are generated by the sea‐bottom deformation caused by earthquakes, some tsunamis are excited by sea‐surface pressure changes. This study theoretically investigated tsunamis generated by sea‐surface pressure changes and derived the solutions in three‐dimensional (3‐D) space, whereas most past studies employed two‐dimensional equations. Using the solutions, we simulated and visualized tsunami generation by a growing pressure change. Negative pressure change made the sea surface uplifted inside the source region and negative leading waves were radiated from the source region. We also simulated the tsunami generation when the pressure change at the sea surface moves at almost the same speed as the tsunami propagation speed. The tsunami height increased with increasing travel distance, including the dispersion effects. The 3‐D solutions in this study, including vertical velocity distribution, indicate that both tsunami height and sea‐surface pressure changes contribute to ocean‐bottom pressure changes, suggesting the difficulty in measuring tsunami height with ocean‐bottom pressure observations. When the pressure change source was characterized by short‐wavelength components, the dispersion sometimes possibly increased the tsunami height more extensively than the nondispersive tsunamis. The 3‐D solutions are necessary for describing tsunami generation where the long‐wave approximations are not applicable in open oceans.