The Vall`es-Pened`es Fault is a Neogene normal fault marked by the presence of two established ge... more The Vall`es-Pened`es Fault is a Neogene normal fault marked by the presence of two established geothermal systems at La Garriga-Samalús and Caldes de Montbuí, within the Catalan Coastal Ranges (NE Spain). The analysis and collation of existing and new geological and geophysical datasets provide the basis for the development of an improved conceptual model that explains the presence and localization of hot geothermal fluid systems at relatively shallow depths (e.g., 60 ◦C at surface and 90 ◦C at 1 km). Geothermal flow is concentrated within Paleozoic granodiorites of the immediate footwall of the V-P fault, host rocks that are susceptible to faultrelated fracturing, and the generation of both extension and hybrid fracture systems in association with active fault displacements. Flow localization is enhanced further by the presence of fault-related structural complexities, with both systems marked by 300 m wide steps in the main fault trace. These are attributed to relay development and breaching characterizing host rocks by high fracture intensities and fault rock development on a fault that locally has a vertical displacement of over 1.5 km. Accentuated fracturing and deformation are consistent with strain localization predicted by existing models for the development of fault zones along normal faults. The plumbing of the geothermal systems is attributed to up-fault flow in combination with lateral flow controlled by the intersection of the V-P fault with a low-angled Paleogene thrust defining the base of the hostrock granodiorites, with the geothermal systems localized at the distal end of the thrust. Sustained geothermal flow is attributed to groundwater flow circulation associated with seismic pumping and valving of warmer and deeper fluids, and the ingress of groundwater along faults and within fractured basement rocks.
Electromagnetic imaging has been perfected to investigate the subsurface over the past three deca... more Electromagnetic imaging has been perfected to investigate the subsurface over the past three decades. Developing numerical schemes, algorithms, and easy access to supercomputers have supported innovation throughout the geo-electromagnetic community. Now, with the Exascale computing era dawning upon us, even more accurate, clearer, and faster data will be within our reach. However, numerical methods, computational strategies, and codes must be reshaped and honed to prepare for the upcoming challenges. Europe is making a huge effort in the strategic global race to Exascale, with large investments in the infrastructure. From the point of view of science and services, this unprecedented infrastructure opens a myriad of possibilities but, at the same time, the transition is challenging and requires a joint effort from (geo)scientists, mathematics, software engineers, and data analysts. Herein, we discuss the symbiotic relationship between numerical methods and computational strategies fo...
The characterization and monitoring of saline water interface is a key issue to understand the ev... more The characterization and monitoring of saline water interface is a key issue to understand the evolution of groundwater resources in coastal areas. In order to go beyond the current knowledge in this issue a new experimental site has been constructed in the lower part of an alluvial aquifer north of Barcelona (Spain). The site, between 30 and 90 m from the seashore comprises 16 shallow piezometers with depths ranging between 15 and 25 meters. Piezometers are also equipped with electrodes in order to perform cross-hole electrical resistivity tomography (CHERT). Periodic CHERT measurements are carried out between the piezometer equipped with electrodes, resulting in parallel and perpendicular vertical cross sections of the site resistivity. The position of the fresh-salt water interface can be identified due to the resistivity contrast between the saline and fresh water. Together with the fiber optics and CHERT investigations, Rn and Ra isotopes are analysed in different piezometers. ...
The study of salt structures is an important challenge because of its economic implications. In t... more The study of salt structures is an important challenge because of its economic implications. In this work La Rosa Diapir has been taken as an example of salt structure because is still active showing an outcrop in good conditions. This diapir is located on Eastern External Prebetic (in Jumilla, southeast Spain). The aim of this work was to perform a reconnaissance MT survey to obtain a first interpretation of the diapir area with this technique. This area is moderately populated and its geological structure is complex. The profile ran along NW-SE direction, and 16 stations were collected on it. The distance between them was approximately 800 m. The effect of the power lines were detected in the apparent resistivity curves, and the shift filters showed its capacity to reduce it. The dimensional analysis confirmed that the geoelectrical structure is 3D. Since the data have been recorded along a profile, the interpretation is based on the determinant of impedance. The results in the area indicate that the geoelectrical structure is quite conductive and no clear traces of resistive bodies can be seen.
<p>The characterization of fresh submarine groundwater discharge (FSGD) in ... more <p>The characterization of fresh submarine groundwater discharge (FSGD) in coastal aquifers has been the object of study in many investigations due to the importance of water as a strategic resource for populations. However, investigating processes that occur in the part of the aquifer located under the sea entails greater difficulties. <br>The objective of this study has been to characterize FSGD in the coastal alluvial aquifer of Maresme, located 40 km north of the city of Barcelona. To study the marine part of the aquifer with good spatial resolution, the geophysical method of continuous resistivity profiling (CRP) has been chosen. Marine profiles, parallel and perpendicular to the coastline, have been done using a boat in a shallow water area to obtain electrical resistivity data of the seabed covering 3 km<sup>2</sup>. Data acquisition has been carried out in two field campaigns, one in the dry season and another in the wet season. <br>From the results obtained, it has been possible to observe different electrical resistivity values in marine sediments along the coast. These variations have also been identified between the two campaigns, being the wet season the one with the highest electrical resistivity values. This study shows that CRP is a non-invasive method that allows the detection of resistive zones of marine sediment that have been related to preferential discharge areas.</p><p>Acknowledgments<br>This work was partly funded by the Spanish Government (grant no. PID2019-110212RB-C22) and the project TerraMar (grant no. ACA210/18/00007) of the Catalan Water Agency.</p>
The Vall`es-Pened`es Fault is a Neogene normal fault marked by the presence of two established ge... more The Vall`es-Pened`es Fault is a Neogene normal fault marked by the presence of two established geothermal systems at La Garriga-Samalús and Caldes de Montbuí, within the Catalan Coastal Ranges (NE Spain). The analysis and collation of existing and new geological and geophysical datasets provide the basis for the development of an improved conceptual model that explains the presence and localization of hot geothermal fluid systems at relatively shallow depths (e.g., 60 ◦C at surface and 90 ◦C at 1 km). Geothermal flow is concentrated within Paleozoic granodiorites of the immediate footwall of the V-P fault, host rocks that are susceptible to faultrelated fracturing, and the generation of both extension and hybrid fracture systems in association with active fault displacements. Flow localization is enhanced further by the presence of fault-related structural complexities, with both systems marked by 300 m wide steps in the main fault trace. These are attributed to relay development and breaching characterizing host rocks by high fracture intensities and fault rock development on a fault that locally has a vertical displacement of over 1.5 km. Accentuated fracturing and deformation are consistent with strain localization predicted by existing models for the development of fault zones along normal faults. The plumbing of the geothermal systems is attributed to up-fault flow in combination with lateral flow controlled by the intersection of the V-P fault with a low-angled Paleogene thrust defining the base of the hostrock granodiorites, with the geothermal systems localized at the distal end of the thrust. Sustained geothermal flow is attributed to groundwater flow circulation associated with seismic pumping and valving of warmer and deeper fluids, and the ingress of groundwater along faults and within fractured basement rocks.
Electromagnetic imaging has been perfected to investigate the subsurface over the past three deca... more Electromagnetic imaging has been perfected to investigate the subsurface over the past three decades. Developing numerical schemes, algorithms, and easy access to supercomputers have supported innovation throughout the geo-electromagnetic community. Now, with the Exascale computing era dawning upon us, even more accurate, clearer, and faster data will be within our reach. However, numerical methods, computational strategies, and codes must be reshaped and honed to prepare for the upcoming challenges. Europe is making a huge effort in the strategic global race to Exascale, with large investments in the infrastructure. From the point of view of science and services, this unprecedented infrastructure opens a myriad of possibilities but, at the same time, the transition is challenging and requires a joint effort from (geo)scientists, mathematics, software engineers, and data analysts. Herein, we discuss the symbiotic relationship between numerical methods and computational strategies fo...
The characterization and monitoring of saline water interface is a key issue to understand the ev... more The characterization and monitoring of saline water interface is a key issue to understand the evolution of groundwater resources in coastal areas. In order to go beyond the current knowledge in this issue a new experimental site has been constructed in the lower part of an alluvial aquifer north of Barcelona (Spain). The site, between 30 and 90 m from the seashore comprises 16 shallow piezometers with depths ranging between 15 and 25 meters. Piezometers are also equipped with electrodes in order to perform cross-hole electrical resistivity tomography (CHERT). Periodic CHERT measurements are carried out between the piezometer equipped with electrodes, resulting in parallel and perpendicular vertical cross sections of the site resistivity. The position of the fresh-salt water interface can be identified due to the resistivity contrast between the saline and fresh water. Together with the fiber optics and CHERT investigations, Rn and Ra isotopes are analysed in different piezometers. ...
The study of salt structures is an important challenge because of its economic implications. In t... more The study of salt structures is an important challenge because of its economic implications. In this work La Rosa Diapir has been taken as an example of salt structure because is still active showing an outcrop in good conditions. This diapir is located on Eastern External Prebetic (in Jumilla, southeast Spain). The aim of this work was to perform a reconnaissance MT survey to obtain a first interpretation of the diapir area with this technique. This area is moderately populated and its geological structure is complex. The profile ran along NW-SE direction, and 16 stations were collected on it. The distance between them was approximately 800 m. The effect of the power lines were detected in the apparent resistivity curves, and the shift filters showed its capacity to reduce it. The dimensional analysis confirmed that the geoelectrical structure is 3D. Since the data have been recorded along a profile, the interpretation is based on the determinant of impedance. The results in the area indicate that the geoelectrical structure is quite conductive and no clear traces of resistive bodies can be seen.
<p>The characterization of fresh submarine groundwater discharge (FSGD) in ... more <p>The characterization of fresh submarine groundwater discharge (FSGD) in coastal aquifers has been the object of study in many investigations due to the importance of water as a strategic resource for populations. However, investigating processes that occur in the part of the aquifer located under the sea entails greater difficulties. <br>The objective of this study has been to characterize FSGD in the coastal alluvial aquifer of Maresme, located 40 km north of the city of Barcelona. To study the marine part of the aquifer with good spatial resolution, the geophysical method of continuous resistivity profiling (CRP) has been chosen. Marine profiles, parallel and perpendicular to the coastline, have been done using a boat in a shallow water area to obtain electrical resistivity data of the seabed covering 3 km<sup>2</sup>. Data acquisition has been carried out in two field campaigns, one in the dry season and another in the wet season. <br>From the results obtained, it has been possible to observe different electrical resistivity values in marine sediments along the coast. These variations have also been identified between the two campaigns, being the wet season the one with the highest electrical resistivity values. This study shows that CRP is a non-invasive method that allows the detection of resistive zones of marine sediment that have been related to preferential discharge areas.</p><p>Acknowledgments<br>This work was partly funded by the Spanish Government (grant no. PID2019-110212RB-C22) and the project TerraMar (grant no. ACA210/18/00007) of the Catalan Water Agency.</p>
Uploads
Papers by Pilar Queralt