Crustal Structure of Southern Baja California Peninsula, Mexico, From Magdalena Microplate to Farallon Basin

Wide-angle seismic data were used to investigate the crustal structure of a transect between the Magdalena Microplate to the Farallon Basin in the Gulf of California, crossing the southern Baja California Peninsula to the north of La Paz (Mexico). This is the first deep seismic study in the area, providing information of the fossil subduction zone of the Magdalena Microplate under Baja California. We have also obtained results of the seismic structure of major fault zones in the area such as Tosco-Abreojos and Santa Margarita. Seismic data were recorded by Ocean Bottom Seismometers (OBS) in the Pacific and the Gulf of California and by portable seismic instruments onshore. More than 5000 offshore high-volume air gun shots were used as energy source in both sides of the Peninsula. Wide-angle data were processed to enhance the signal to noise ratio to help in the identification of the seismic energy arrivals. We used a direct method of interpretation, including ray tracing, travel times and synthetic seismograms calculation. The availability of a number of recording instruments allows multiple coverage of the crustal structure.