The relationship between wind, waves, bathymetry, and microseisms in Yellowstone Lake, Yellowstone National Park

Abstract

We conducted a multidisciplinary geophysical experiment to study the relationship between wind, waves, bathymetry, and microseisms in Yellowstone Lake—a small, isolated body of water in which wind-driven gravity waves excite low-amplitude seismic energy at periods ∼1.0 s with a regular daily pattern. During 25 June–4 August 2018, we deployed 40 short-period seismometers, four meteorological stations, and two wave gauges in and around Yellowstone Lake. These instruments were complemented by seven permanent seismometers on the lake perimeter, and a contemporaneous deployment of 10 lake bottom seismometers (LBS) on the floor of the north-central portion of the lake. The daily wind cycle, with southwesterly winds rising from ∼0 m/s in the early morning to maxima of 10–15 m/s in the late afternoon, generated lake waves with significant heights of ∼0.3–0.4 m and dominant periods of 1.5–2.5 s, which in turn generated microseisms with dominant periods of ∼0.8–1.2 s, in excellent agreement with the double-frequency generation mechanism. Microseism energy was strongest on the lake floor stations, followed by the island stations and those along the northeastern coast of the lake, suggesting that these sites are closest to the source region where interference between incident and shoreline-reflected waves is responsible for microseism generation. Smaller amplitude single-frequency microseism energy was observed primarily along the northeastern lake shoreline. Both types of microseism energy are sensitive to shoreline morphology and lake wave dynamics, such that long-term monitoring of lake microseisms may further our understanding of how these processes change over time.