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Aiming at the large aspect ratio characteristics of large wind turbines, it is easy to cause irreversible damage due to flutter during operation. A two-degree-of-freedom (plunge and pitch) flutter test bench was built using the time domain and frequency domain analysis methods of dynamic signals. The influence of different centroid positions on the flutter boundary was studied. The test shows that the closer the centroid position is to the leading edge of the wing segment, the better the aeroelastic stability of the wing segment is. Under the linear condition, the forward movement of the centroid position has a more significant influence on the flutter. In addition, the main reason for the wing flutter is related to the decrease of net damping and the coupling of the aeroelastic natural frequency of the pitching and plunging motions. The pitch motion is dominant in the two-degree-of-freedom motion. The farther the centre of mass is from the torsion axis, the greater the pitch and plunge motion displacement. The pitch motion has a more significant impact on the system than the plunge motion. Therefore, the study of flutter suppression should focus on pitch motion., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Strong tsunami excitation from slow rupture of shallow subduction zone faults is recognized as a key concern for tsunami hazard assessment. Three months after the 22 July 2020 magnitude 7.8 thrust earthquake struck the plate boundary below the Shumagin Islands, Alaska, a magnitude 7.6 aftershock ruptured with complex intraplate faulting. Despite the smaller size and predominantly strike-slip faulting mechanism inferred from seismic waves for the aftershock, it generated much larger tsunami waves than the mainshock. Here we show through detailed analysis of seismic, geodetic, and tsunami observations of the aftershock that the event implicated unprecedented source complexity, involving weakly tsunamigenic fast rupture of two intraplate faults located below and most likely above the plate boundary, along with induced strongly tsunamigenic slow thrust slip on a third fault near the shelf break likely striking nearly perpendicular to the trench. The thrust slip took over 5 min, giving no clear expression in seismic or geodetic observations while producing the sizeable far-field tsunami., (© 2023. The Author(s).)