Angela G Marusiak

Geology Department University of Maryland    marusiak@umd.edu

My research can be divided between a focus on Mars and the icy moon, Europa.

Mars:

In 2018 NASA plans to send seismometers to Mars aboard the InSight (INterior Exploration using Seismic Investigations, Geodesy, and Heat Transport) mission. As part of mission preparations, I'm using terrestrial events to test the quantity and quality of events that would be required to constrain the depth to the Martian Core. I created 22 models based on the PREM model with core depths between 2791-2991km in increments of 10km. I randomly select terrestrial events and stack their amplitudes at each model's expected time of arrival. The difference between actual and predicted arrival times are also compared. Using this method, I'm able to test how many events are required to constrain the core depth. I have also tested how the quality of events affects core depth uncertainty. Location uncertainty was also added to quantify its affect on my algorithm.  Preliminary results can be viewed in the LPSC abstracts, (Marusiak et al., 2016) and (Marusiak et al., 2017). You can also see the final results in our Icarus paper.

Image Credit: JPL/NASA

Icy Moons:

Europa and Enceladus are two icy moons that have subsurface oceans beneath their exterior icy shells. Because of the potential habitability of these oceans, NASA has made studying these moons a priority. Specific interests include determining the seismicity of the icy shells and the structure of the ice shells and oceans.

To determine the capabilities of seismometers, I use analog sites and instruments in Alaska and Greenland. I use active source experiments to compare instruments, and placements on the ground to placements on a table to simulate different placements on a lander. The active source is also used to determine P and S wave arrivals that are used with a Bayesian Inversion code to determine the local structure of the ice.(Marusiak et al., 2018) Another Bayesian Inversion code is used to locate the active source and compare the results to the known locations. Eventually passive sources can be identified using the location algorithm and the peak frequencies of their signals. This work will be translated to Europan synthetic seismograms to determine if a singe-station seismometer can identify and locate the events.

This part of my thesis was conducted with the SIIOS (Seismometer to Investigate Ice and Ocean Structure) team. SIIOS team updates can be found on Facebook and Twitter . Preliminary results were presented at AGU and LPSC 2018.

Image Credit: JPL/NASA