Sebastian Carrasco

Ruhr-Universität Bochum | RUB · Institute of Geology, Geophysics and Mineralogy

The 2007 seismic swarm in the Aysen Fjord, whose main earthquake took place on April 21 of that year and reached a Mw 6.2 magnitude, has been one of the most recent important seismic sequences that may have been associated with the Liquiñe-Ofqui Fault Zone. In May 2018, thanks to the seismological stations belonging to the National Network of Volca...

The H/V spectral ratio inversion is a traditional technique for deriving the local subsurface structure on Earth. We calculated the H/V from the ambient vibrations at different wind levels at the InSight landing site, on Mars, and also computed the H/V from the S-wave coda of the martian seismic events (marsquakes). Different H/V curves were obtain...

For the first time, we measured the ellipticity of direct Rayleigh waves at intermediate periods (15–35 s) on Mars using the recordings of three large seismic Martian events, including S1222a, the largest event recorded by the InSight mission. These measurements, together with P‐to‐s receiver functions and P‐wave reflection times, were utilized for...

We detected surface waves from two meteorite impacts on Mars. By measuring group velocity dispersion along the impact-lander path, we obtained a direct constraint on crustal structure away from the InSight lander. The crust north of the equatorial dichotomy had a shear wave velocity of approximately 3.2 kilometers per second in the 5- to 30-kilomet...

Convective vortices (whirlwinds) and dust devils (dust‐loaded vortices) are one of the most common phenomena on Mars. They reflect the local thermodynamical structure of the atmosphere and are the driving force of the dust cycle. Additionally, they cause an elastic ground deformation, which is useful for retrieving the subsurface rigidity. Therefor...

Plain Language Summary The source of a quake is a key piece of information to uncover the dynamic process at the source region. In terrestrial seismology, the source of a quake can be described with a classical model in which the spectra decay with frequency at a certain speed. In this study, we focus on one key source parameter of S1222a, the corn...

Convective vortices (whirlwinds) and dust devils (dust-loaded vortices) are one of the most common phenomena on Mars, observable on a daily basis. They reflect the local thermodynamical structure of the atmosphere and are the driving force of the dust cycle. Additionally, they cause an elastic ground deformation, which is useful for retrieving the...

Plain Language Summary The seismometers deployed at the surface of Mars in the framework of the Interior Exploration using Seismic Investigations, Geodesy and Heat Transport mission have recently recorded seismic waves generated by meteorite impacts and a very large Marsquake. These exceptional data offer the opportunity to study how seismic waves...

For the first time, we measured the ellipticity of direct Rayleigh waves at long periods (15 - 35 s) on Mars using the recordings of three large seismic martian events, including S1222a, the largest event recorded by the InSight mission. These measurements, together with P-to-s receiver functions and P-wave reflection times, were utilized for perfo...

Prior to the 2018 landing of the InSight mission, the InSight science team proposed locating Marsquakes using multiple orbit surface waves, independent of seismic velocity models, for events larger than MW4.6. The S1222a MW4.7 of 4 May 2022 is the largest Marsquake recorded and the first large enough for this method. Group arrivals of the first thr...

Surface waves had not been observed on any marsquake records during the first 3 years of seismic monitoring on Mars. We report the first detection of surface waves on Mars from two meteoroid impacts. The observed surface waves allow us to expand the current understanding of crustal structure on Mars beyond the crustal layering inferred beneath the...

Hobiger, M., Hallo, M., Schmelzbach, C. et al. (2021): The shallow structure of Mars at the InSight landing site from inversion of ambient vibrations. Nat. Commun. 12, 6756, https://doi.org/10.1038/s41467-021-26957-7.

Orbital and surface observations can shed light on the internal structure of Mars. NASA's InSight mission allows mapping the shallow subsurface of Elysium Planitia using seismic data. In this work, we apply a classical seismological technique of inverting Rayleigh wave ellipticity curves extracted from ambient seismic vibrations to resolve, for the...

Since its deployment at the surface of Mars, the Seismic Experiment for Interior Structure (SEIS) instrument of the InSight mission has detected hundreds of small-magnitude seismic events. In this work, we highlight some features of two specific families: high-frequency (HF) and very-high-frequency (VF) events. We characterize the shape of the ener...

Human activity causes vibrations that propagate into the ground as high-frequency seismic waves. Measures to mitigate the COVID-19 pandemic caused widespread changes in human activity, leading to a months-long reduction in seismic noise of up to 50%. The 2020 seismic noise quiet period is the longest and most prominent global anthropogenic seismic...

The Juan Fernandez Islands (JFI) are located in the Pacific Ocean 675 km west of the Chilean coast. This archipelago has historically been affected by large tsunamis. Robinson Crusoe Island (RCI), the main island of the JFI, was first inhabited in 1749. Since then, several tsunamis have destroyed RCI port structures and sometimes caused deaths. Gro...

On 25 December 2016, a Mw 7.6 earthquake broke a portion of the Southern Chilean subduction zone south of Chiloé Island, located in the central part of the Mw 9.5 1960 Valdivia earthquake. This region is characterized by repeated earthquakes in 1960 and historical times with very sparse interseismic activity due to the subduction of a young (~15 Ma...

The Finite-Fault Rupture Detector (FinDer) algorithm provides real-time finite-source models for on-going fault ruptures. The FinDer algorithm determines a line-source model that is best suited to explain the current spatial ground-motion pattern observed at any given time in a dense seismic network. This is done via the cross-correlation of observ...

Rapid knowledge of seismic source parameters and accurate ground-motion predictions are key to Earthquake Early Warning (EEW), which aims to warn the community before shaking initiates. In recent decades, a variety of EEW algorithms have been proposed, including FinDer (Finite-Fault Rupture Detector). In contrast to other algorithms, FinDer estimat...