ABSTRACT
Two >130-meter-diameter impact craters formed on Mars during the later half of 2021. These are the two largest fresh impact craters discovered by the Mars Reconnaissance Orbiter since operations started 16 years ago. The impacts created two of the largest seismic events (magnitudes greater than 4) recorded by InSight during its 3-year mission. The combination of orbital imagery and seismic ground motion enables the investigation of subsurface and atmospheric energy partitioning of the impact process on a planet with a thin atmosphere and the first direct test of martian deep-interior seismic models with known event distances. The impact at 35°N excavated blocks of water ice, which is the lowest latitude at which ice has been directly observed on Mars.
ABSTRACT
We report the analysis of the statistics of the phase fluctuations in the coda of earthquakes recorded during a temporary experiment deployed at Pinyon Flats Observatory, California. The observed distributions of the spatial derivatives of the phase in the seismic coda exhibit universal power-law decays whose exponents agree accurately with circular Gaussian statistics. The correlation function of the phase derivative is measured and used to estimate the mean free path of Rayleigh waves.
ABSTRACT
We report the observation of weak localization of seismic waves in a natural environment. It emerges as a doubling of the seismic energy around the source within a spot of the width of a wavelength, which is several tens of meters in our case. The characteristic time for its onset is the scattering mean-free time that quantifies the internal heterogeneity.
ABSTRACT
We present theory and numerical simulations to model seismic wave propagation in the Earth crust. We compare them to observations made in Mexico.
ABSTRACT
Calculation of coherent backscattering of elastic waves in an infinite isotropic random medium is presented. Despite the simplicity of this geometry, this calculation highlights several specific aspects for seismic detection: near field detection, polarization, and the symmetry of the source. Line profiles and enhancement factors are seen to be time independent and are calculated for kinetic, shear, and compressional energy.
ABSTRACT
Equipartition is a first principle in wave transport, based on the tendency of multiple scattering to homogenize phase space. We report observations of this principle for seismic waves created by earthquakes in Mexico. We find qualitative agreement with an equipartition model that accounts for mode conversions at the Earth's surface.
