San Miguel Volcanic Seismicity and Structure in Central America: Insight into the Physical Processes of Volcanoes

San Miguel volcano lies near the city of San Miguel, El Salvador (13.43°N, 88.26°W). An active stratovolcano, it presents a significant natural hazard for the city of San Miguel. In general, the internal state and activity of volcanoes like San Miguel remains an important component to understanding volcanic hazards. The main technology for addressing volcanic hazards and associated processes is through the analysis of data collected from the deployment of seismic sensors that record ground motion. Six seismic stations were deployed by UTEP around San Miguel volcano during the 2007-2008 the time period to define internal structure or magmatic plumbing system of the magma chamber and assess the seismic and volcanic hazards associated with the volcano. I utilize these data to develop images of the Earth structure beneath the volcano, to study the volcanic processes by identifying different sources, and to investigate the role of earthquakes and faults in controlling the volcanic processes. I initially locate events using automated routines and focus on analyzing local events. I then relocate each seismic event by hand-picking P-wave arrivals and later refine these picks using waveform cross correlation. Using a double difference earthquake location algorithm (HypoDD), a set of earthquakes that vertically align beneath the edifice of the volcano has been identified and interpreted to be a magma conduit feeding the volcano. I investigate the volcano\u27s plumbing system using a double-difference earthquake tomography (DD tomography) approach. Another tomography approach, fast marching tomography (FMTomo), is used to produce a model that approximates the ray paths and velocity perturbations using a finite difference method. Overall, San Miguel presents a significant hazard to the region showing volcanic gases, historic flank eruptions, and fissure activity (Escobar, 2003). The results show gas migration propagating through out the plumbing system correlating at the same period using the radar interferometry (InSAR) approach done by the Schiek et al. (2009) during March 29, 2007 to April 16, 2007