The Los Humeros Volcanic Complex (LHVC) is a large silicic caldera complex in the Trans-Mexican Volcanic Belt (TMVB), hosting a geothermal field currently in exploitation by the Comisión Federal de Electricidad (CFE) of Mexico, with an installed capacity of ca. 95 MW of electric power. Understanding the structural architecture of LHVC is important to get insights into the interplay between the volcano-tectonic setting and the characteristics of the geothermal resources in the area. The analysis of volcanotectonic interplay in LHVC benefits from the availability of subsurface data obtained during the exploration of the geothermal reservoir that allows the achievement of a 3D structural view of the volcano system. The LHVC thus represents an important natural laboratory for the development of general models of volcano-tectonic interaction in calderas. In this study, we discuss a structural model of LHVC based on morphostructural and field analysis, integrated with well logs, focal mechanism solutions and magnetotelluric imaging. The structural analysis suggests that inherited regional tectonic structures recognized in the basement played an important role in the evolution of the magma feeding system, caldera collapses and post-caldera deformations. These inherited weak planes have been reactivated by resurgence faults and post-caldera magma-driven hydrofractures under a local radial stress field generated by the shallow LHVC magmatic/hydrothermal system. The local stress field induced caldera resurgence and volcanotectonic faulting. The results of this study are important to better constrain the structural architecture of large caldera complexes. Also, our study is useful to understand the structure of the Los Humeros geothermal field and support the exploration of deeper Super-Hot Geothermal Systems (SHGSs) and engineering of Enhanced Geothermal Systems (EGSs) for electric power production in the LHVC and other active resurgent calderas.

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A combined analysis of geochemical and production data of 39 wells of the Los Azufres (Mexico) geothermal field (227.4 MWe) over time was developed to investigate the exploitation-related processes for 2003-2011. In the south zone, important effects of reinjection were observed through Cl increases in some wells (up to 8000 mg/kg) while in wells with significant boiling, Cl has decreased. In most of the north zone wells, the variations in gas data indicated boiling and condensation of a highly gas-depleted brine, which seems to consist of reinjection fluids. It is suggested that this process maintains the production in the zone relatively stable. The main reservoir exploitation-related processes found were: 1) production of reinjection returns; for this, it was possible to distinguish a) wells that produce liquid and steam from injection, and b) wells that produce steam from injection and sometimes condensed steam from injection; 2) boiling: two types of boiling were identified: a) boiling with steam gain, and b) boiling with steam loss. The results indicated that an effective reservoir recharge occurs since very moderate production declining rates were found.

Lima is a city of 10 million inhabitants, and 60% of its population lives in slums settlements. Due to its location in the Circum Pacific Belt of Fire, this is a high-seismic activity area. Despite this fact, there is a serious lack of urban planning and natural disaster planning. After decades of neglect by Latin American governments in terms of planning, a quantitative risk assessment to determine population exposure is imperative, as well as it is also mandatory to propose an evacuation plan to mitigate, as far as possible, the post-earthquake effects. "El Progreso" sector located in Carabayllo, a Lima district in Peru, was selected as the case study because it is one of the slum settlements with the highest potential risk as it is located in a basin surrounded by hills due to the effects of informal constructions (such as ceilings). Filled with rocks and walls) their slopes have suffered much more deterioration than in other hillsides. In addition, this area is prone to debris avalanches, rock fragments, debris flows among other geologic hazards. First step is start to identify all the existing risks such as: the height of buildings near the escape routes, illegally parked vehicles (mainly taxis and Peruvian motorcycle taxis), current traffic on the streets, distance to the evacuation areas, flow capacity of escape routes, flows of pedestrian moving in opposite directions, slopes and types of floor of escape routes, danger of avalanche and falling rocks. Then, risks will be classified using the Analytic Hierarchy Process AHP to obtain the cost function for roads. Then, two evacuation models based on linear programming are presented minimizing risk functions. Finally, two evacuation models based on linear programming are presented.