Using fine electromagnetic signals to measure observables of other fields like curvature and torsion of a space, and the corresponding value of their integrals of the action of perception of curvature through electronic signals that detect curvature on a curved surface, it is designed and constructed a sensor of curvature of accelerometer type that detects and curvature measures in 2 and 3-dimensional spaces using the programming of shape operators on spheres and the value of their integrals along the curves and geodesics in their principal directions.

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We relocated the hypocentral coordinates of small to moderate-sized earthquakes reported by the National Earthquake Information Center (NEIC) between April 2002 and August 2006 in the Gulf of California region and recorded by the broadband stations of the network of autonomously recording seismographs (NARS-Baja array). The NARS-Baja array consists of 19 stations installed in the Baja California peninsula, Sonora and Sinaloa, Mexico. The events reported by the preliminary determinations of epicenters (PDE) catalog within the period of interest have moment magnitudes (M w ) ranging between 1.1 and 6.7. We estimated the hypocentral location of these events using P and S wave arrivals recorded by the regional broadband stations of the NARS-Baja and the RESBAN (Red Sismolo´gica de Banda Ancha) arrays and using a standard location procedure with the HYPOCENTER code (LIENERT and HAVSKOV in Seism Res Lett 66:26-36, 1995) as a preliminary step. To refine the location of the initial hypocenters, we used the shrinking box source-specific station term method of LIN and SHEARER (J Geophys Res 110, B04304, 2005). We found that most of the seismicity is distributed in the NW-SE direction along the axis of the Gulf of California, following a linear trend that, from north to south, steps southward near the main basins (Wagner, Delfin, Guaymas, Carmen, Farallon, Pescadero and Alarcon) and spreading centers. We compared the epicentral locations reported in the PDE with the locations obtained using regional arrival times, and we found that earthquakes with magnitudes in the range 3.2-5.0 mb differ on the average by as much as 43 km. For the M w magnitude range between 5 and 6.7 the discrepancy is less, differing on the average by about 25 km. We found that the relocated epicenters correlate well with the main bathymetric features of the Gulf.

On 3 August 2009 an earthquake of magnitude M w 6.9 occurred near Canal de Ballenas, in the north-central region of the Gulf of California, Mexico. The focal mechanism of the main event, reported in the Global Centroid Moment Tensor (CMT) catalog, is right lateral strike-slip with a strike of 216°and a dip of 78°. The initial location reported by the National Seismological Service of Mexico [Servicio Sismólogico Nacional (SSN)] and the Array Network Facility (ANF) suggested that the epicenter was on the North American plate near the Tiburón fault, which is considered inactive. This earthquake was preceded by a magnitude m b 5.5 event that occurred about 5 min before. In the next 40 min after the main event two aftershocks with magnitudes m b 4.9 and M w 6.2 occurred, and on 5 August a third aftershock of M w 5.7 was located in the Canal de Ballenas region. The events of August 2009 were recorded by the regional stations of the broadband network Red Sismólogica de Banda Ancha (RESBAN) that Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE) operates and by stations of the SSN also located in the region of the Gulf of California. We used body-wave arrivals to determine precise epicentral locations and to estimate the rupture area of this important sequence of earthquakes. The resulting hypocentral coordinates indicate that the main event of this sequence occurred along the Canal de Ballenas transform fault, with a rupture length of 50 km. Based on the aftershock distribution, we estimate that the main event had a rupture area of approximately 600 km 2 , an average slip of 1.3 m, and a stress drop of 2.2 MPa.

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