Juan Martín Gómez-González

Crust and subduction zone structure of Southwestern Mexico

Southwestern Mexico is a region of complex active tectonics with subduction of the young Rivera and Cocos plates to the south and widespread magmatism and rifting in the continental interior. Here we use receiver function analysis on data recorded by a 50 station temporary deployment of seismometers known as the MARS (MApping the Rivera Subduction zone) array to investigate crustal structure as well as the nature of the subduction interface near the coast. The array was deployed in the Mexican states of Jalisco, Colima, and Michoacan. Crustal thickness varies from 20 km near the coast to 42 km in the continental interior. The Rivera plate has steeper dip than the Cocos plate and is also deeper along the coast than previous estimates have shown. Inland, there is not a correlation between the thickness of the crust and topography indicating that the high topography in northern Jalisco and Michoacan is likely supported by buoyant mantle. High crustal Vp/Vs ratios (greater than 1.82) are found beneath the trenchward edge of magmatism including below the Central Jalisco Volcanic Lineament and the Michoacan-Guanajuato Volcanic Field implying a new arc is forming closer to the trench than the Trans Mexican Volcanic Belt. Elsewhere in the region, crustal Vp/Vs ratios are normal. The subducting Rivera and Cocos plates are marked by a dipping shear wave low-velocity layer. We estimate the thickness of the low-velocity layer to be 3 to 4 km with an unusually high Vp/Vs ratio of 2.0 to 2.1 and a drop in S velocity of 25%. We postulate that the low-velocity zone is the upper oceanic crust with high pore pressures. The low-velocity zone ends from 45 to 50 km depth and likely marks the basalt to eclogite transition.

Seismic site effects in the central zone of Monterrey Metropolitan Area (northeast Mexico) from a geotechnical multidisciplinary assessment

Prediction of the ground shaking response requires data expressed in terms of soil dynamic properties. Based on the analysis of surficial geology, geotechnical borehole data, seismic refraction (VS) and microtremors (H/V) surveys, we have developed a qualitative evaluation of local ground response to earthquakes in the Monterrey Metropolitan Area (MMA), the main urban and economic hub in northern Mexico. The results provide a detailed geotechnical model for the central zone of the MMA. Although such information is not yet complete for the MMA region, an initial approach has been developed in order to estimate the distribution of damage associated with expected moderate earthquakes. An empirical correlation is introduced to obtain VS as a function of standard penetration test blow counts (SPTN). According to the results, the central-southern part of the study area might experience higher amplifications of ground shaking produced by moderate seismicity because the larger thicknesses of alluvial sediments are deposited there. The 2D geotechnical model proposed would be very useful in making decisions regarding planning or land use, deployment of protocols of rapid response and for producing detailed microzonation maps for those zones with similar geological features as the MMA in northeast Mexico.

Educative ECG Platform for Undergraduate Courses in BME

In the area of Biomedical Instrumentation and Physiology, the teaching process is commonly supported by commercial instrumentation systems, frequently used with minimal understanding of the fundamental principles of registering and processing physiological signals. In BME-closing module at Faculty of Engineering, National Autonomous University of Mexico, the Fundamentals of Biomedical Instrumentation and Introduction to Physiology courses, are in need to put in practice theoretical subjects, using accessible equipment. Therefore, an instrument to register and display ECG signals was developed for educational purpose, training students in topics such as: identify main problems when acquiring biosignals, designing customized instrumentation systems and biosignal processing. Development was conducted using free licensed software such as IDE Arduino for hardware controller and, Phyton, Processing and Octave for signal display and processing data, making accessible the use of this platform in both courses. Theoretical and practical knowledge obtained will allow students to continue his/her career as designer/developer of instrumentation systems –hardware and software- for research, as well as in medical equipment maintenance.

Assessment of Ankle Movements Through a Game-Based Sphere: Proof of Concept

Ankle movements are complex and play a key role in displacement and manipulation of equipment. This paper presents a novel game-based device to assess the ankle movements. The system is composed by a hemisphere, a smartphone, a software application for the smartphone and another one for the computer. The hemisphere acts as the main interface between the foot and the software application. Through the hemisphere, which acts as a pointer or jositick for the foot, the user guides a pointer through a hexagonal trajectory. This allows assessing the ankle movements. The developed system was tested with 11 subjects. Preliminary result shows the potential of the system.