Seismic imaging of the magmatic plumbing system and geothermal reservoir of the Los Humeros caldera (Mexico) using anisotropic shear wave models

Chavarrí­a, Iván Granados; Calò, Marco; Figueroa-Soto, Á.; Jousset, Philippe

doi:10.1016/j.jvolgeores.2021.107441

Cited by 14 publications

(7 citation statements)

References 86 publications

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“…Data are resampled at 20 sps and filtered between 0.2 and 10 Hz assuming the lowest group velocity is 0.7 km/s and the largest interstation distance is 8.5 km. Data processing follows the scheme proposed by Bensen et al (2007) and modified by Granados-Chavarría et al (2022). Daily records are cut into 30-min time windows and one-bit normalization and spectral whitening are applied to each time window.…”

Section: Methodsmentioning

confidence: 99%

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Ambient Noise Tomography of the Lipari Volcanic Island (Southern Italy) From a Dense Nodal Array

Calò

Luccio

Persaud

et al. 2023

Geophysical Research Letters

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Section: Methodsmentioning

confidence: 99%

“…(2007) and modified by Granados‐Chavarría et al. (2022). Daily records are cut into 30‐min time windows and one‐bit normalization and spectral whitening are applied to each time window.…”

Section: Methodsmentioning

confidence: 99%

Ambient Noise Tomography of the Lipari Volcanic Island (Southern Italy) From a Dense Nodal Array

Calò

Luccio

Persaud

et al. 2023

Geophysical Research Letters

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“…Low velocity zones at different depths could be causing anisotropy and hence would be an alternative explanation for what we see in the results. Granados-Chavarría et al (2022) have shown that the low velocity zones correspond to the exploited geothermal reservoir itself, thus corresponding to areas of high thermal state and fluid flow. Low shear wave velocity transmission causes these low velocity zones, which likely correlates to the presence of water (Granados-Chavarría et al, 2022).…”

Section: Low Velocity Zones and Vp/vs Ratiomentioning

confidence: 99%

“…Granados-Chavarría et al (2022) have shown that the low velocity zones correspond to the exploited geothermal reservoir itself, thus corresponding to areas of high thermal state and fluid flow. Low shear wave velocity transmission causes these low velocity zones, which likely correlates to the presence of water (Granados-Chavarría et al, 2022). Therefore, hydrothermal activity is evident in these areas, which may be affecting the anisotropy in the subsurface, bequeathing further exploitation capabilities.…”

Section: Low Velocity Zones and Vp/vs Ratiomentioning

confidence: 99%

Constraints on Fracture Distribution in the Los Humeros Geothermal Field From Beamforming of Ambient Seismic Noise

Kennedy

Löer

Gilligan

2022

Preprint

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Abstract. Faults and fractures are crucial parameters for geothermal systems as they provide secondary permeability allowing fluids to circulate and heat up in the subsurface. In this study, we use an ambient seismic noise technique referred to as three-component (3C) beamforming to detect and characterise faults and fractures at a geothermal field in Mexico. We perform 3C beamforming on ambient noise data collected at the Los Humeros Geothermal Field (LHGF) in Mexico. The LHGF is situated in a complicated geological area, being part of a volcanic complex with an active tectonic fault system. Although the LHGF has been exploited for geothermal resources for over three decades, the field has yet to be explored at depths greater than 3 km. Consequently, it is currently unknown how deep faults and fractures permeate and the LHGF has yet to be exploited to its full capacity. 3C beamforming extracts the polarizations, azimuths, and phase velocities of coherent waves as a function of frequency, providing a detailed characterisation of the seismic wavefield. In this study, 3C beamforming of ambient seismic noise is used to determine surface wave velocities as a function of depth and propagation direction. Anisotropic velocities are assumed to relate to the presence of faults giving an indication of the maximum depth of permeability, a vital parameter for fluid circulation and heat flow throughout a geothermal field. 3C beamforming was used to determine if the complex surface fracture system permeates deeper than is currently known. Our results show that anisotropy of seismic velocities does not decline significantly with depth, suggesting that faults and fractures, and hence permeability, persist below 3 km. Moreover, estimates of fast and slow directions, with respect to surface wave velocities, are used to determine the orientation of faults with depth. The North-East (NE) and North-North-West (NNW) orientation of the fast direction corresponds to the orientation of the Arroyo Grande and Maxtaloya-Los Humeros fault swarms respectively. NE and NNW orientations of anisotropy align with other major faults within the LHGF at depths permeating to 6 km.

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“…Several geophysical studies have been carried out in the area; potential field (e.g. Flores et al, 1977;Campos-Enríquez and Arredondo-Fragoso, 1992;Arzate et al, 2018), active and passive seismicity (Urban and Lermo, 2013;Jousset et al, 2020;Granados-Chavarría et al, 2022) and thermal modeling (Deb et al, 2021). Regarding the techniques used to estimate the subsurface electrical resistivity, studies have been carried out with 413 direct current resistivity soundings (Palacios-Hartweg and García-Velázquez, 1981;Cedillo-Rodríguez, 1999), 61 transient electromagnetic soundings (Seismocontrol, 2005), and two magnetotelluric (MT) studies by Arzate et al (2018), andBenediktsdóttir et al (2020), with 70 and 122 soundings, respectively.…”

Section: Geological and Geophysical Backgroundmentioning

confidence: 99%

Seal Cap Resistivity Structure of Los Humeros Geothermal Field from Direct Current and Transient Electromagnetic Soundings

2022

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Los métodos geofísicos dan información importante en la exploración de recursos geotérmicos. En este trabajo buscamos pistas de la presencia de un yacimiento geotérmico conocido (Los Humeros, México) en la estructura somera de la resistividad eléctrica. Interpretamos cerca de 410 sondeos eléctricos verticales (SEV) y 230 sondeos electromagnéticos transitorios (TEM) que dan información de la resistividad eléctrica hasta profundidades de 1 km, alcanzándose en algunos sitios hasta 2 km.La estructura vertical de la resistividad generalmente consiste de una secuencia resistivo-conductor-resistivo. El rasgo más importante es la unidad conductora, conocida como el casquete de arcillas, asociado con arcillas de alteración hidrotermal arriba del yacimiento geotérmico. Esta unidad sufre de un problema de equivalencia, donde no se pueden determinar por separado su resistividad de su espesor. Sin embargo, las temperaturas de los pozos y las arcillas de alteración asociadas ayudan a constreñir este problema. En varias zonas de la unidad resistiva somera encontramos resistividades bajas que podrían representar zonas de recarga donde roca fracturada permite la infiltración de agua meteórica. El casquete de arcillas no solo se presenta sobre el yacimiento, sino que tiene una presencia regional. Sin embargo, sobre el reservorio esta unidad tiene una mayor conductancia y su cima está más somera. Los pocos lugares donde los sondeos eléctricos alcanzaron profundidades del yacimiento con resistividades bien resueltas dan una resistividad media de 118 ohm▪m, sin poder diferenciar estadísticamente las zonas productoras de las no productoras. Esta resistividad está dentro del rango de valores encontrados en otras zonas geotérmicas del mundo.

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Seismic imaging of the magmatic plumbing system and geothermal reservoir of the Los Humeros caldera (Mexico) using anisotropic shear wave models

Cited by 14 publications

References 86 publications

Ambient Noise Tomography of the Lipari Volcanic Island (Southern Italy) From a Dense Nodal Array

Ambient Noise Tomography of the Lipari Volcanic Island (Southern Italy) From a Dense Nodal Array

Constraints on Fracture Distribution in the Los Humeros Geothermal Field From Beamforming of Ambient Seismic Noise

Seal Cap Resistivity Structure of Los Humeros Geothermal Field from Direct Current and Transient Electromagnetic Soundings

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