Anna Gabàs

Ambient seismic noise acquired in the Cerdanya Basin (eastern Pyrenees) is used to assess the capability of different methodologies to map the geometry of a small-scale sedimentary basin. We present results based on a 1-year-long broad-band deployment covering a large part of the eastern Pyrenees and a 2-month-long high-density deployment covering...

A broad understanding of the subsoil characteristics is required to deal with uncertainty in the infrastructure planning phase or even in the diagnosis of infrastructure damage. In this work, electrical resistivity and seismic methods have been employed for lithological characterization and geomechanical parameters assessment. The study area is cha...

Ambient seismic noise acquired in the Cerdanya Basin (Eastern Pyrenees) is used to assess the capability of different methodologies to map the geometry of a small-scale sedimentary basin. We present results based on a 1-year long broad-band deployment covering a large part of the Eastern Pyrenees and a 2-months long high-density deployment covering...

The acquisition and interpretation of gravity and magnetic data represents a cost-effective tool in geophysics since it allows to determine the geometry and distribution of the density and magnetic properties at depth of the subsurface rocks. The study area, where gravity and magnetic data have been interpreted, is the La Cerdanya basin (Eastern Py...

Surface electrical resistivity tomography is a non-invasive and highly competitive technique that can be used to effectively characterize subsurface sediments for different purposes: geological, geotechnical, hydrogeological or subsidence problems. However, due to the strong effect of salinity on resistivity, sediments characterization in deltas (c...

Identification of undercover karst areas can be essential for engineering or hydrogeological studies. Geological reconnaissance of karst areas can be challenging due to their complex and highly heterogeneous internal structure. Herein, we present a case study carried out at the carbonate coastal Montgrí Massif in Costa Brava (Spain), which, in the...

The integration of geophysical methods, together with the previous information of the Vallès basin area, has resulted in the creation of a new conceptual model that explains La Garriga-Samalús geothermal system. The integration of complementary geophysical methods seems to be a good option for the preliminary stages of a geothermal system explorati...

Amplitude level, duration, and spectral content of earthquake ground motions are strongly influenced by local soil conditions. Reliable estimation of site effects is, therefore, crucial in order to avoid damage to infrastructures and mitigate other losses. Traditional geophysical exploration techniques are restricted in urban environments due to th...

Within the framework of Alertes-RIM (Regional and on-site earthquake early warning system for the Ibero-Maghrebian region) project twenty five seismic stations located in this region have been characterized. The aim of this work is the application of a methodology based on combination of active and passive seismic techniques in order to study poten...

The Ebro Delta (Spain) faces anthropogenic and climate changes that can cause a significant decrease on its subaerial surface. One of the causes of this reduction is subsidence that take place due to the compacting of the sediments. In order to identify zones vulnerable to subsidence, we have defined several targets such as: characterization of Hol...

The structure of Cerdanya Basin (north-east of Iberian Peninsula) is partly known from geological cross sections, geological maps and vintage geophysical data. However, these data do not have the necessary resolution to characterize some parts of Cerdanya Basin such as the thickness of soft soil, geometry of bedrock or geometry of geological units...

We combine geophysical well logging and passive seismic measurements to characterize the near-surface geology of an area located in Hontomin, Burgos (Spain). This area has some near-surface challenges for a geophysical study. The irregular topography is characterized by limestone outcrops and unconsolidated sediments areas. Additionally, the near-s...

We combine geophysical well logging and passive seismic measurements to characterize the near surface geology of an area located in Hontomin, Burgos (Spain). This area has some near-surface challenges for a geophysical study. The irregular topography is characterized by limestone outcrops and unconsolidated sediments areas. Additionally, the near s...

The purpose of this work is the application of a dynamic methodology developed by the Institut Cartografic i Geologic de Catalunya which uses diverse geophysical techniques to study five seismic station of the Catalonia Seismic Network. This methodology changes depending on a priori geological knowledge and the dimensions of area. The method adapts...

This work shows the potential of reprocessing land seismic vintage data acquired for oil exploration to increase knowledge of near-surface geological structure in a Neogene Basin. The study area is the Emporda Basin, located in NE Spain. The objective is to reveal main contacts in the Neogene sequence and bedrock geometry. The methodology encompass...

In the last two decades, the horizontal-to-vertical (H/V) spectral ratio of seismic noise technique has been widely used for site-effect estimation and geophysical exploration through the soil fundamental frequency. Usually, only one peak is observed in the H/V spectral ratio, but in some cases, a second peak can also be obtained. Nevertheless, to...

This study reveals the importance of reprocessing vintage seismic data, originally focused on deep targets, in order to retrieve near-surface velocity model and structure. This information can be verified and complemented using cost-effective geophysical methods (passive seismic and audio-magnetotelluric - AMT data technique). This methodology has...

A sedimentary Tertiary basin filled with unconsolidated sediments located in eastern Pyrenees has been subjected to a combine passive geophysical survey in order to increase knowledge of bedrock geometry and sediment properties. The methodology consists of combining and integrating both seismic noise techniques (H/V and array) and audio-magnetotell...

Urban geological mapping is a key to assist management of new developed areas, conversion of current urban areas or assessment of urban geological hazards. Geophysics can have a pivotal role to yield subsurface information in urban areas provided that geophysical methods are capable of dealing with challenges related to these scenarios (e.g., low s...

Coastal aquifer formations located in Northeast of Spain affected by saline intrusion has been the focus for a multi-technique geophysical study. Two aquifers are present: A shallow aquifer in the quaternary sediments and a deeper karstic aquifer. The objectives were: (1) estimate quaternary sediment thickness and characterize weathered/fractured r...

Mapping bedrock structure beneath overburden is crucial for understanding geological and hydrogeological processes. Acquiring this information is generally done using well drilling or geophysical surveys; but these studies are expensive and require large periods of acquisition and processing time. In addition, geophysical data acquisition can be lo...

We present a geophysical study where different geophysical techniques are combined to support an urban geological mapping project in NE of Spain. The study has been carried out at two different scales. Seismic and electrical resistivity tomography methods have provided a subsoil image up to 30/40 m depth supported by surface-wave and H/V microtremo...

The application of traditional geophysical techniques such as seismic or electrical resistivity tomography (ERT) in broad areas requires large period of time. In this work a methodology is proposed in order to optimize the data acquisition time in the determination of the weathered materials thickness overlaying the unaltered rock in a large area....

The Baixa Tordera alluvial aquifer system is located in the northeastern Mediterranean coast of Spain. This system is considered as a strategic aquifer for planning the management of regional water resources. Since the 1980s, this area has been the subject of an important tourist and industrial development that has incremented the water demand. The...

Diverse magnetotelluric data (apparent resistivity, phase or geomagnetic transfer function) used during the inversion process provide different information on the model as a consequence of data error. The relative influence of these data constitutes a subject of interest on the inversion process. This influence can be evaluated from the error ratio...

Galvanic distortion of magnetotelluric (MT) data is a common problem in the study of the Earth's electrical properties. These distortions are local, they affect independently each MT site, and where restricted to distortion of the electric field are manifest as vertical shifts in the apparent resistivity curves (static shift). The removal of the st...