Mars Structure Service: Single-Station and Single-Event Marsquake Inversion for Structure Using Synthetic Martian Waveforms

Date: 4/25/2019

Time: 09:15 AM

Room: Vashon

The InSight lander successfully delivered geophysical instrument package on the Martian surface on November 26th, 2018, including a broadband and a short-period seismometer (Seismic Experiment for Interior Structure, SEIS). Routine operations are split into two services: the Mars Structure Service (MSS) and the Marsquake Service (MQS), which are responsible for defining structure models and seismicity catalogs, respectively. The first “deliverable” of the MSS will be a model based on the events detected during the first 3 months of seismic monitoring of the mission, for which only a few quakes might be expected based on current estimates of Mars seismic activity. To test our approach of determining the interior model of Mars and to prepare the InSight science team for data return, we made use of a “blind test” time series for which the Marsquake parameters (location, depth, origin time, and moment tensor) and interior model were unknown to the group at large.

In preparation for the mission, the goal was to develop mature algorithms to handle the data as efficiency as possible. Synthetic seismic waveforms were computed in a 1D mantle model with a 3D crust on top using AxiSEM and Salvus. The time series were created by adding seismic noise that relies on pre-landing estimates of noise generated by the sensors, electronic system, environment, and nearby lander.

We detail and compare the results of this “blind test” using different methods including inversion of surface wave dispersion data, body waves travel times, and the waveforms themselves. Effects of fixing mars quake location and origin time are investigated. To allow for tighter constraints, we also test the use of priors based on thermodynamically-constrained models. These techniques considered here form a large part of the planned modeling of the MSS that will be ultimately employed with the first recording of a seismic event by InSight.

Presenting Author: Mark P. Panning

Authors