Constraints on Midmantle Discontinuities in Mars from Analysis of InSight Seismic Data


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Date

2025-04

Publication Type

Journal Article

ETH Bibliography

yes

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Data

Abstract

The structure and nature of Earth’s transition zone, which is delineated by the transformation of olivine to its higher-pressure polymorphs, exerts a strong influence on material transfer between upper and lower mantle. Mars, however, because of its relatively large core, is only expected to exhibit the equivalent of Earth’s uppermost transition zone seismic discontinuity. We searched the InSight seismic data for marsquakes and impacts located in an epicentral distance range favorable for detection of seismic phases that have interacted with Mars’s olivine transition (midmantle) discontinuity. Through application of careful data selection criteria and processing schemes, we found 13 events in the distance range in which body waves are expected to refract through the midmantle of Mars. Although triplicated body waves are potentially present in seven events, the distance distribution is insufficient to allow for unambiguous detection of the triplicated waveform pattern associated with the midmantle discontinuity. Comparison of travel times of the observed waveforms with predictions from recent Mars models indicates the possible presence of a midmantle discontinuity located between 987 and 1052 km or 1075 and 1122 km depth, in which the uncertainty comes from our inability to reliably distinguish first from secondary arrivals.

Publication status

published

Editor

Book title

Volume

5 (2)

Pages / Article No.

207 - 217

Publisher

Seismological Society of America

Event

Edition / version

Methods

Software

Geographic location

Date collected

Date created

Subject

Organisational unit

09495 - Murakami, Motohiko / Murakami, Motohiko

Notes

Funding

ETH-02 19-1 - Magnetotelluric investigation of active rifting and the formation of geothermal energy resources in Ethiopia - MIRIGE-ETH (ETHZ)
197369 - Towards a self-consistent Earth model from multi-scale joint inversion: Revealing Earth's mantle elasticity and density with seismic full-waveform inversion, tidal tomography and homogenization (SNF)

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