Casas, Jordi JuliàSantos, Miro Feliciano Döring dos2018-12-122021-09-202018-12-122021-09-202018-11-29SANTOS, Miro Feliciano Döring dos. Método de Geiger modificado: Localização hipocentral e inversão para velocidade. 2018. 52 f. Trabalho de Conclusão de Curso (Graduação em Geofísica) - Departamento de Geofísica, Universidade Federal do Rio Grande do Norte, Natal, 2018.https://repositorio.ufrn.br/handle/123456789/34352Geiger’s method of hypocentral location is a non-linear optimization problem that determines the origin time (t0) and the hypocentral coordinates of the seismic source (x0,y0,z0) from the arrival time of P and/or S waves recorded at seismic stations. The method, in its traditional form, requires the assumption of the speed of propagation of the seismic wave, which is usually chosen from a trial-and-error process that involves multiple inversions and analysis of the root-mean-square (RMS) as a function of wave speed. The current project seeks to modify Geiger's algorithm in order to determine both the source parameters and the speed of propagation in a single inversion run. To that purpose, Geiger’s method was modified to invert arrival times from multiple events and simultaneously determine their hypocentral coordinates and a common wave speed. The new algorithm was tested on synthetic data, with and without noise, where simulating two situations: One in which a network of 5 stations was centered around a target earthquake, and another one in which 5 stations were surrounding several earthquakes distributed randomly. Both methodologies, traditional and modified, retrieved the true focal parameters with similar accuracy, demonstrating that constraining the wave speed within a single inversion is possible and that the simultaneous inversion of multiple events with the modified Geiger’s method is straightforward. A practical test was also performed with data collected through a local seismic network that operated in Irauçuba/CE during a period of intense local seismicity. The network was deployed between September 2015 and March 2016, and consisted of 7 seismic stations that operated continuously and recorded up to 22 local events. Our results demonstrate that the source parameters and the propagating wave speed can be accurately constrained through the modified Geiger’s method proposed in this study.SeismicityGeiger's MethodHypocentral LocationSismicidadeMétodo de GeigerLocalização HipocentralbachelorThesis