Fields of research

My scientific interests, with a short description of my contributions to related research projects are the following:

Table of Contents

Seismology focused on extraterrestrial activity. Comparative analysis of Earth, Mars, Moon.

In the end of the 19th century the first seismometers were deployed on Earth and for the first time seismic waves were recorded in teleseismic distances. In 1969, the first seismometer was deployed on the ground of an extraterrestrial world, when the Apollo 11 mission installed the first Lunar Seismometer. In 2018, the first seismometer was deployed on the ground of another planet, when the InSight SEIS instrument was deployed on the surface of Mars. Through seismic investigations we can now perform comparative analysis of those three bodies, understand their internal structure and obtain useful constraints about their evolution.

Forward modeling of seismic waves using normal mode summation and spectral element method.

Forward modeling of seismic waves permits an investigation where a theoretical structure model is tested against real seismic data. With different methods, we compute seismograms with the goal to understand the appropriate model that will provide the best fit between theoretical computed seismograms and actual recordings.

The normal mode summation methodology is based on the free oscillations of the Earth or any planetary body. The seismic source is a perturbation in the natural resonances of modes. This perturbation can be decomposed in spherical harmonics, where the corresponding modes are oscillating in different frequencies (eigenfrequencies). The summation of all the computed excitations of these perturbations can provide a synthetic seismogram, corresponding to a recording in a range of selected frequencies.

The spectral element method is a methodology based on the numerical modeling of continuum mechanics. Finite elements represent the material in a mesh and the perturbation is corresponding to a force or moment tensor. The displacement of finite elements in another point of the model space, where a receiver is supposed to exist, enables to compute theoretical seismograms for given stations, existing, planned or even imaginary.

Study of seismic wave excitation in solid Earth by Meteor impacts - and their dispersion in the coupled atmosphere-solid Earth system.

The meteors are objects that enter the atmosphere of a planetary body. The process of their ablation in the atmosphere and the possibility of finally reaching the solid part of the target body depends in many parameters, as the meteoroid entry angle, the speed in the atmosphere, its size and composition, as well as the density of the atmosphere and others. When the meteors explode in the atmosphere, airburst events generate shock waves that travel in the atmospheric part with an overpressure and generate seismic waves through the coupling of the system of the atmosphere and the solid planet. When these bodies reach the ground, meteor impacts occur and the shock waves are generated also in the solid part, before converting to linear seismic waves after some distance of propagation, characterized by a decreasing rate of their initial overpressure, measured or calculated at the source.

Inversion of meteors as seismic sources. Investigation of associated shock wave generation and propagation.

The generation of atmospheric and solid shock waves and the consequent generation of acoustic waves in the atmosphere and seismic waves in the solid part, by sources associated with meteor impacts, is a complex phenomenon. The source is actually moving in the atmosphere and therefore a point source is not the best way to represent the physical mechanism of wave generation. Through approximations of a line source we can obtain a more accurate modeling of wave generation and therefore more accurate explanation of the propagation to a receiver instrument (seismometer).

Laboratory measurements of elastic properties of soils

Through well established tests for materials, a variety of properties of soils can be measured in laboratory. These tests are very useful as preliminary studies for the preparation of seismic investigation experiments in remote places or/and planetary bodies.