IN MEMORIAM: JOSÉ DOUGLAS FREZ CÁRDENAS (1936 – 2025)
José Douglas Frez Cárdenas, a retired seismologist from the Centro de Investigación Científica y de Educación Superior de Ensenada, Baja California (CICESE), passed away on 23 June 2025 in Tijuana, Baja California, Mexico. He joined CICESE in March 1981 at the Department of Geophysics which, after some years, became in two Departments: Seismology and Applied Geophysics. His academic trajectory at CICESE ended in January 2021.
José’s research interests were seismicity, seismotectonics, and computational seismology. Before he incorporated at CICESE, an ML 6.1 earthquake occurred on 9 June 1980 along the Cerro Prieto fault. A study, in which he was a collaborator, found that this earthquake had a right-lateral faulting mechanism and generated a PGA of 1.0 g at 10 km from the epicenter (Wong et al., 1997, Geofis. Int. 36, 3, 139-159). At Northern Baja California (NBC), seismicity also arise perpendicular to the northwest-trending faults. José and colleagues studied the Ojos Negros area located between the central segment of the San Miguel Fault and the Tres Hermanas fault (Frez et al., 2000, BSSA, 90, 5, 1133-1142). Most of the focal mechanisms they found were strike-slip with a minor normal component, and others were normal, indicating that the main tectonic stress acting on this area is tensional. The difficulty in determining the fault plane using focal mechanisms, or the Moment Tensor technique, is known. José proposed a method to determine the fault plane based on the directivity Doppler effect (Frez et al., 2010, BSSA, 100, 1, 289-297). The authors successfully applied this method to small earthquakes (1.2 ≤ M ≤ 3.6) of NBC.
Finally, José, a good professor, graduated six Master’s in Science students and taught some seismology courses. One iconic course he designed is Inversion Theory, which nowadays is a fundamental course in Seismology and Applied Geophysics at CICESE.