Journal Article

Snow Suppresses Seismic Signals From Steamboat Geyser

Manga, Michael, Reed, Mara H.

2023

Overview

Geyser and volcano monitoring suffer from temporal, geographic, and instrumental biases. We present a recording bias identified through multiyear monitoring of Steamboat Geyser in Yellowstone National Park, USA. Eruptions of Steamboat are the tallest of any geyser in the world and they produce broadband signals at two nearby stations in the Yellowstone National Park Seismograph Network. In winter, we observe lower eruption signal amplitudes at these seismometers. Instead of a source effect, we find that environmental conditions affect the recorded signals. Lower amplitudes for 23–45 Hz frequencies are correlated with greater snow depths at the station 340 m away from Steamboat, and we calculate an energy attenuation coefficient of 0.21 ± 0.01 dB per cm of snow. More long‐term monitoring is needed at geysers to track changes over time and identify recording biases that may be missed during short, sporadic studies. Plain Language Summary What we learn about geysers and volcanoes depends on when, where, and how we are able to monitor them. Here we present a case study of how seasonal changes affect data recorded on a seismometer, which is an instrument that measures ground motion. The world's tallest geyser, Steamboat Geyser in Yellowstone National Park, has intense eruptions that eject a mixture of water and steam. The eruptions are powerful enough to cause tiny ground motions from sound waves that begin in the air and then transfer into the ground. In the winter, we see smaller ground motions at two nearby seismometers. This might imply that Steamboat's eruptions are weaker in the winter; however, winter in Yellowstone comes with snow, and snow is good at absorbing sound wave energy. We find that smaller ground motions occur when snow depths are greater, and that the strength of ground motions should not be used to directly compare eruption intensity. Few geysers around the world are monitored with scientific equipment for long periods of time. Our result highlights the need for more of this type of monitoring so that we can identify biases that may be missed during shorter investigations. Key Points Seismic signals from Steamboat Geyser eruptions contain ground‐coupled airwaves at distances up to 2.2 km Snow dampens airwave arrivals leading to lower apparent signal amplitudes in winter Interpretation of eruption signals at both geysers and volcanoes should take changing environmental factors into account

• Publisher: John Wiley & Sons, Inc,Wiley
• Subject: Amplitudes / Attenuation coefficients / Bias / Boats / Broadband / Environmental conditions / Eruptions / Extinction coefficient / geyser / Geysers / Ground motion / ground‐coupled airwaves / Hot springs / National parks / Recording / Seasonal variations / Seismographs / Seismometers / Snow / snow acoustics / Sound transmission / Sound waves / Volcano monitoring / Volcanoes / Wave energy / Winter / Yellowstone