Marsquake Locations and 1-D Seismic Models for Mars From InSight Data

Area of Science:

• Planetary Science
• Seismology
• Geophysics

Background:

• The InSight lander provided the first seismic data from Mars.
• Understanding Mars' interior structure is crucial for planetary evolution studies.

Purpose of the Study:

• To determine the interior structure of Mars using seismic data.
• To constrain the location of marsquakes and their source regions.
• To investigate the thermal state and long-term evolution of Mars.

Main Methods:

• Analysis of seismic body waves (direct, multiples, depth phases) from 17 marsquakes.
• One-dimensional inversion of seismic arrival times to model interior structure.
• Integration of seismic data with gravity, topography, and previous analyses.

Main Results:

• Marsquake hypocenters are shallower than 40 km, primarily in the Cerberus Fossae region.
• A significant velocity jump in the crust indicates a transition from intrusive to extrusive rocks.
• The lower crust is substantial, with seismic velocities suggesting mafic to ultramafic compositions.
• Estimated present-day surface heat flux: 22 ± 1 mW/m², mantle potential temperature: 1740 ± 90 K, lithosphere thickness: 540 ± 120 km.
• Lithospheric thermal gradient is 1.9 ± 0.3 K/km.
• Mars' initial mantle temperature was colder than present, and its crust is enriched in heat-producing elements.

Conclusions:

• The Cerberus Fossae region is a likely source of marsquakes.
• The Martian crust exhibits distinct layers with varying rock compositions.
• Mars has a relatively hot interior and a thick lithosphere, indicating significant internal heat.
• The planet's thermal evolution suggests a cooling mantle and enriched crust over time.