The Seismic Noise Environment of Europa

Seismic data will be a vital geophysical constraint on internal structure of Europa if we land instruments on the surface. Quantifying expected seismic noise on Europa is an important consideration for instrument and mission design.

Noise will likely include cracking in the ice shell and turbulent motion in the oceans. We define a range of models of seismic activity in Europa’s ice shell by assuming each model follows a Gutenberg-Richter relationship with varying parameters. A range of cumulative seismic moment release between $10^{16}$ and $10^{18}$ Nm/yr is defined by scaling tidal dissipation energy to tectonic events on the Earth’s moon. Random catalogs are generated and used to create synthetic noise records through numerical wave propagation in thermodynamically self-consistent models of the interior structure of Europa. Spectral characteristics of the noise are calculated by determining probabilistic power spectral densities of the synthetic records.

While the range of seismicity models predicts noise levels that vary by 80 dB, we show that most noise estimates are below the self-noise floor of high-frequency geophones, but may be recorded by more sensitive instruments. Such instruments appear likely to be able to record signals from the largest events expected during a window of a few weeks. Noise records may allow for constraints on interior structure through autocorrelation. Models of seismic noise generated by pressure variations at the base of the ice shell due to turbulent motions in the subsurface ocean may also generate observable seismic noise.

Mark P. Panning, Simon C. Stähler, Hsin-Hua Huang, Steven D. Vance, Sharon Kedar, Victor Tsai, W. T. Pike, Ralph D. Lorenz
(Submitted on 9 May 2017)

Comments: 21 pages, 10 figures
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:1705.03424 [astro-ph.EP] (or arXiv:1705.03424v1 [astro-ph.EP] for this version)
Submission history
From: Mark Panning
[v1] Tue, 9 May 2017 16:54:01 GMT (1330kb,D)
http://xxx.lanl.gov/abs/1705.03424

Astrobiology