Could Some Mars Seismic Events be Generated by Fluid Flow?

Tuesday, 15 December 2020
Scott D King1, Sharon Kedar2, Mark P Panning3, Suzanne E Smrekar4, Matthew P Golombek2, Michael Manga5, Bruce R Julian6, Brian Shiro7, Clement Perrin8, John A Power9, Chloe Michaut10, Domenico Giardini11, Simon C Staehler12, Philippe Henri Lognonné13 and William Bruce Banerdt14, (1)Virginia Polytechnic Institute and State University, Blacksburg, VA, United States, (2)JPL, Pasadena, CA, United States, (3)Univ of FL-Geological Sciences, Gainesville, FL, United States, (4)NASA Jet Propulsion Laboratory, Pasadena, CA, United States, (5)Univ of California Berkeley, Berkeley, CA, United States, (6)USGS California Water Science Center Menlo Park, Menlo Park, CA, United States, (7)USGS Hawaii Volcano Observatory, Hawaii Natl Park, HI, United States, (8)Université de Paris, Institut de Physique du Globe de Paris, CNRS, Paris, France, (9)USGS, Alaska Volcano Observatory, Anchorage, AK, United States, (10)Institut de Physique du Globe, Paris cedex 13, France, (11)Swiss Federal Institute of Technology (ETH), Zurich, Switzerland, (12)ETH Zurich, Department of Earth Sciences, Institute of Geophysics, Zurich, Switzerland, (13)Université de Paris, Institut de physique du globe de Paris, CNRS, Paris, France, (14)JPL/NASA/Caltech, Pasadena, CA, United States
The InSight Mission began acquiring the first seismic data on Mars in early 2019 and has detected hundreds of very small events. About 10% of the quakes to date are identified by their Low Frequency (LF) content (< 1 Hz), a portion of these share the characteristics of Long Period fluid induced tremor observed in terrestrial magmatic systems. This study aims to answer whether these events can be explained by fluid flow at depth, and if so, what are the flow properties and physical regimes that best match the observations? We used a tremor source model that simulates the generation of tremor as pressurized fluid makes its way across a channel. This enabled the analysis of a wide range of physical parameters such as fluid viscosity, the ratio of driving pressure to lithostatic pressure, aspect ratio of the channel, and the equilibrium channel opening. We assume a source at Cerberus Fossae, a young geologic area characterized by fissures and faults that cut across among the youngest lava flows on the surface of Mars, and where the largest LF events were located. We explore two end-member source depths 6 km and 60 km, and use a Bayesian approach to identify models that match the observed frequency, amplitude and duration. We find that while a flow-induced oscillating channel can produce seismic signals that match the characteristics of the observed signals, in order to match the observation this model requires very large volumes and low viscosities. Bursts of activity that yield magma volume flux as high as ~105 m3/s, while not impossible given the geological history of Cerberus Fossae, make this mechanism a possible yet an unlikely explanation for the seismic signal.