Seminário de Avaliação - Série A: Full-waveform reconstruction of microseismic events from acoustic pressure measurements: single- and multi-frequency approaches in two and three dimensions

Orientadores:
Antônio André Novotny - Laboratório Nacional de Computação Científica - LNCC

Banca Examinadora:
Antônio André Novotny - Laboratório Nacional de Computação Científica - LNCC (presidente)
Hugo Saraiva Tavares - Laboratório Nacional de Computação Científica - LNCC
Alan Alves Santana Amad - Laboratório Nacional de computação científica - LNCC

Suplentes:
Lucas dos Santos Fernandez - Laboratório Nacional de Computação Científica - LNCC

Resumo:

In this thesis, we develop a hydroacoustic full-waveform framework for reconstructing microseismic events in a solid body from acoustic pressure measurements recorded in the surrounding fluid. The work is motivated by the need to locate and characterize reaction-driven cracking in geologic formations relevant to permanent carbon storage and other subsurface monitoring applications. We formulate the inverse problem as the recovery of source location and seismic moment tensor from sparse pressure observations, using a coupled solid-fluid forward model, an admissible- source search over a prescribed grid, and adaptive grid refinement to improve the accuracy of off-grid events. The methodology is first investigated in two dimensions for single-frequency data, then extended to multi-frequency observations to assess how temporal aperture can compensate for limited spatial aperture, and finally generalized to a three-dimensional configuration with full moment tensor recovery. Numerical experiments show that hydroacoustic pressure data contain sufficient information to recover source location and mechanism under sparse sensing, and that multi-frequency info rmation improves robustness and resolution. The resulting framework offers a promising route for hydrophone-based monitoring.