Elsa Leticia Flores-Márquez

Multifractal detrended fluctuation analysis of earthquake magnitude series of Mexican South Pacific Region

The multifractality of the earthquake magnitude series of seismicity occurred on the Mexican South Pacific Coast was investigated. The area is composed by five seismic regions that are characterized by different tectonic subduction features, due to the interactions between the La Rivera and Cocos plates with the North America plate. Among the five seismic regions, Jalisco is tectonically characterized by the existence of active spreading center (the East Pacific Rise). The multifractal analysis shows that all the five seismic regions are characterized by very close multifractal properties; however, Jalisco is featured by a higher persistence of the magnitude series.

The Complexity Measures Associated with the Fluctuations of the Entropy in Natural Time before the Deadly México M8.2 Earthquake on 7 September 2017

We analyse seismicity during the 6-year period 2012–2017 in the new time domain termed natural time in the Chiapas region where the M8.2 earthquake occurred, Mexico’s largest earthquake in more than a century, in order to study the complexity measures associated with fluctuations of entropy as well as with entropy change under time reversal. We find that almost three months before the M8.2 earthquake, i.e., on 14 June 2017, the complexity measure associated with the fluctuations of entropy change under time reversal shows an abrupt increase, which, however, does not hold for the complexity measure associated with the fluctuations of entropy in forward time. On the same date, the entropy change under time reversal has been previously found to exhibit a minimum [Physica A 506, 625–634 (2018)]; we thus find here that this minimum is also accompanied by increased fluctuations of the entropy change under time reversal. In addition, we find a simultaneous increase of the Tsallis entropic index q.

Image-radargram analysis based on generalized Hough transform: experimental cases

This paper presents an algorithm based on the generalized Hough transform (GHT) to enhance geological structures in a 2D profile image constructed from ground-penetrating radar data. The proposed algorithm is applied over an edge representation image of the radargram; its local application (in Windows) allows us to identify structures and to obtain a global image delimiting the subsurface structures of interest. To show and validate the program, it was applied to two experimental cases: the first one is a profile of volcanic stratigraphic structures, and the second one consists of three buried pipes. The GHT algorithm enhances the main geological structures for both examples. Due to the use of a monostatic antenna in the case of buried pipes, a proper velocity analysis could not be done. As a consequence, the radargram remained under-migrated leaving some traces of diffraction hyperbola tails. These traces were detected by the GHT; therefore, a robust algorithm was designed to adjust a circle over these hyperbola traces. This secondary algorithm is called ‘circular structure determination’.

Scaling properties of rainfall records in some Mexican zones

Since the 1990 decade, it has been suggested that atmospheric processes associated with rainfall could be a self-organized critical (SOC) phenomenon similar, for example, to seismicity. In this sense, the rain events taken as the output of the complex atmospheric system (sun’s radiation, water evaporation, clouds, etc.) are analogous to earthquakes, as the output of a relaxation process of the earth crust. A clue on this possible SOC behavior of rain phenomenon has been the ubiquitous presence of power laws in rain statistics. In the present article, we report the scaling properties of rain precipitation data taken from meteorological stations located at six zones of Mexico. Our results are consistent with those that assert that rainfall is a SOC phenomenon. We also analyze the Hurst exponent, which is appropriate to measure long-term memory of time series.

Geoelectrical Image of Punta Banda (Baja California, Mexico) Using CSAMT and ERT Data

Due to the population increase, tourism development and insufficient water supply in desert zones in the northern of the Mexico, demanding of drinking water has become a government priority. In order to face this situation the IMPULSA research program has been created to develop novel technologies based on desalination of sea and brackish water using renewable energies. The present study aims to obtain a better insight on the Punta Banda geothermal system (Baja California, Mexico), specifically on the structural features related to the thermal anomalies. A preliminary geoelectrical prospection was carried out in the zone to understand the process generating these anomalous temperatures and to assess its potential exploitation. Two geophysical techniques were chosen to approach this objective, the Audiomagnetotelluric method (AMT) and the Electrical Resistivity Tomography (ERT). Two main geoelectrical zones were identified: 1) a shallow low resistivity media located at the central portion of the profile, coinciding with the Maneadero Valley and 2) two high resistive structures bordering the conductive zone, possibly related to NS faulting, already identified by previous geophysical studies. These results suggest that the geothermal anomalies are possible controlled by the dominant structural pattern in the zone.