Abstract
Crescent City Harbor, California, is well known for experiencing severe tsunami impacts. While NOAA tide gauges have routinely measured tsunami water levels for decades, direct observations of tsunami currents in the region remain scarce. Here, we analyze 12 hours of continuous security camera video using wave-dispersion-corrected optical velocimetry (Image Wave Velocimetry) to derive high-resolution surface velocity fields near the small boat basin entrance during the 2025 Kamchatka tsunami. This represents the first application of this technique to continuous tsunami current observations. We demonstrate that moderate vertical water-level fluctuations (±1.1 m) sustained strong surface currents (up to 2.6 m s-1) over dozens of resonant cycles for hours following the initial arrival. Horizontal velocity and surface displacement were in quadrature, consistent with classical theory for standing waves in a semi-enclosed basin. The analysis also resolves the formation and evolution of coherent eddies at the basin entrance.