Open Collections

Jacksteit, Anya

University of British Columbia

Observations of seismic waves are instrumental to understanding the interior structure and composition of the Earth and the Earth’s moon. This study uses data from the Apollo Passive Seismic Experiment to investigate spatial distribution of deep moonquakes (DMQ), seismic events occurring about half-way into the lunar interior. A correlation between DMQ epicenters and the lunar maria has been noted, along with very few DMQ being observed on the lunar far side. It is not clear whether the observed heterogeneity in the locations of DMQ is a result of heterogeneity in lunar structure or whether it is a consequence of the restricted observational network layout. To test the correlation between DMQ and the mare basalts, Nakamura (2005) epicenter locations (referred to here as N05) were used as well as location clouds created using the LOCSMITH program. LOCSMITH produces nodes on a 3-D triangulated grid through the lunar interior that are non-falsified locations for which a DMQ nest could occur at to satisfy the arrival times provided. Created for use with sparse seismic networks, such as the Apollo network, LOCSMITH does not assume that a single arrival time pick is correct, but rather that an arrival time occurring at any point in the window provided is possible. As a control set, random epicenter locations and their resulting LOCSMITH clouds were also generated. DMQ epicenters and LOCSMITH location clouds were tested against two interpretations of mare basalt boundaries to provide information on the relationship between DMQ and the lunar mare basalts. This study showed that DMQ epicenters may be slightly more likely to be located under lunar mare basalt units than if they were randomly placed. Factors that impact this association include error determination method, mare unit boundary definition, and the control set. The likelihood of DMQ epicenters being located beneath the mare was lower when using LOCSMITH nodes than when using the Nakamura (2005) reported epicenters. The number of arrival time picks for a nest makes a significant difference to whether it is more likely to be located beneath the mare than a randomly placed nest or not.

Text

2025-02-20

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/90407

Geophysics

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/