Multi-year Pressure Temperature Records from the Floor of Yellowstone Lake as indicators of Crustal Loading and Deformation
Abstract
Yellowstone Lake straddles the edge of the volcanically active Yellowstone Caldera and hosts a vigorous hydrothermal system along with numerous geologic indicators of volcanic processes from recent geologic history. The time-varying distribution of water in the lake also acts as a load on the thermally weakened crust within the area. As part of the HD-YLAKE project, we deployed an array of sensors recording the pressure field and lake bottom temperature from within and around Yellowstone Lake from 2016 - 2018. We analyze these data both to determine the spatiotemporal character of the load of shifting lake water over time, and to investigate potential deformation of the lake floor that may not be expressed in land-based geodetic records. The total lake level varied by 1.6 m each water year, with strong barotropic seiches (amplitude up to 11 cm) occurring perpetually year round at multiple frequencies, most prominently at 0.214 mHz (78 minute period) and 0.327 mHz (51 minute period). The observed lake-wide distribution of water during strong seiching is consistent with numerical models of the free oscillations expected from Yellowstone Lake bathymetry. An accurate interpretation of the time-varying water load is important, both because it may influence the expression of lake bottom hydrothermal activity over time, and because it is key to interpreting periodic solid earth deformation observed at these frequencies by nearby borehole tiltmeters and strainmeters within the Yellowstone Caldera. We also calculate differential pressure variations between lake bottom stations at periods longer than any observed wave activity. We find effective differential water level changes of up to 2 cm, with preliminary analysis suggesting subtle ground surface deformation is occurring, particularly in the northern part of Yellowstone Lake. Overall, the lake-bottom pressure temperature records presented here offer the most complete spatio-temporal description of the physical dynamics of lake activity available to date.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.V33D0205L
- Keywords:
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- 4302 Geological;
- NATURAL HAZARDS;
- 7280 Volcano seismology;
- SEISMOLOGY;
- 8424 Hydrothermal systems;
- VOLCANOLOGY;
- 8488 Volcanic hazards and risks;
- VOLCANOLOGY