One year of passive seismic monitoring of the Los Humeros (Mexico) geothermal field [in press]
01 Jan 2019-
TL;DR: In this article, an extensive passive seismic monitoring was carried out between Sep. 17 and Sep. 18, 2019 over the Los Humeros (Mexico) geothermal field, which provided numerous data, whose processing is still on-going, to better characterize the underground structures and properties of the geothermal fields.
Abstract: Extensive passive seismic monitoring was carried out between Sep. 17 and Sep. 18 over the Los Humeros (Mexico) geothermal field. This acquisition operation was conducted in the framework of the European H2020 project GEMex among different geophysical, geochemical and geological surveys. Seismic monitoring provided numerous data, whose processing is still on-going, to better characterize the underground structures and properties of the geothermal field. These results participate to the increase of our understanding of the local geothermal system. They can be utilized to propose new development areas, especially, to the north-west of the currently exploited zone, which showed temperatures greater than 380°C at ca. 2.5 km depth. For one year, a network of 45 shortand long-period seismometers was deployed in the surrounding of the Los Humeros geothermal field. The network layout was chosen to comply with several types of passive seismic processing methods: induced and natural seismicity characterization, travel-time tomography, ambient noise tomography, among others. We present here the results associated with the recorded seismicity. Besides several natural earthquakes in the region, induced earthquakes were regularly detected, at a rate higher than one event per day. Most of them were clustered in the vicinity of geothermal wells or known geological structures, at a depth between 1 and 3 km, consistent with the exploited reservoir interval.
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TL;DR: Löer et al. as mentioned in this paper presented a 1D shear-velocity model for Los Humeros geothermal field (Mexico) obtained from three-component beamforming of ambient seismic noise, imaging for the first time the bottom of the sedimentary basement ∼5 km below the volcanic caldera, as well as the brittle-ductile transition at ∼ 10 km depth.
Abstract: Cite this article as Löer, K., T. Toledo, G. Norini, X. Zhang, A. Curtis, and E. H. Saenger (2020). Imaging the Deep Structures of Los Humeros Geothermal Field, Mexico, Using Three-Component Seismic Noise Beamforming, Seismol. Res. Lett. 91, 3269–3277, doi: 10.1785/ 0220200022. Supplemental Material We present a 1D shear-velocity model for Los Humeros geothermal field (Mexico) obtained from three-component beamforming of ambient seismic noise, imaging for the first time the bottom of the sedimentary basement ∼5 km below the volcanic caldera, as well as the brittle-ductile transition at ∼ 10 km depth. Rayleigh-wave dispersion curves are extracted from ambient seismic noise measurements and inverted using a Markov chain Monte Carlo scheme. The resulting probability density function provides the shear-velocity distribution down to 15 km depth, hence, much deeper than other techniques applied in the area. In the upper 4 km, our model conforms to a profile from local seismicity analysis and matches geological structure inferred from well logs, which validates the methodology. Complementing information fromwell logs and outcrops at the near surface, discontinuities in the seismic profile can be linked to geological transitions allowing us to infer structural information of the deeper subsurface. By constraining the extent of rocks with brittle behavior and permeability conditions at greater depths, our results are of paramount importance for the future exploitation of the reservoir and provide a basis for the geological and thermodynamic modeling of active superhot geothermal systems, in general. Introduction Los Humeros volcanic complex (LHVC; Fig. 1), located in the eastern part of the Trans-Mexican volcanic belt (TMVB), hosts a conventional geothermal field (Ferrari et al., 2012; GutiérrezNegrín, 2019). On-going hydrothermal activity makes the LHVC a favorable area for geothermal exploitation, and a geothermal power plant has been operating since the 1990s. The LHVC has been identified as an important natural laboratory for the development of general models of superhot geothermal systems (SHGSs) in volcanic calderas (e.g., Jolie et al., 2018). Although extensive geological field studies and well log analyses have provided many constraints on the near-surface geology of the caldera complex and conventional geothermal reservoir, conditions at depths greater than 2–3 km are largely unknown and currently being studied intensively (Jolie et al., 2018). It is assumed that superhot fluids could exist in the carbonate rock basement underlying the caldera (Jolie et al., 2018). These rocks might exhibit secondary permeability related to the damage zone of active resurgence faults and inherited pervasive basement structures (Lorenzo-Pulido, 2008; Rocha-López et al., 2010; Norini et al., 2015, 2019; Jolie et al., 2018). The maximum depth of these brittle structures is defined by the brittle-ductile (BD) transition zone, which thus plays an important role in geothermal exploration because upper crustal faults and fractures behave as hydraulic channels for the circulation of geothermal fluids (e.g., Ranalli and Rybach, 2005). In SHGSs that exhibit a positive thermal anomaly, the depth of the BD transition may differ from areas with a normal thermal gradient, as rocks become progressively more ductile with increasing temperature. Thus, a positive 1. Department of Civil and Environmental Engineering, Bochum University of Applied Sciences, Bochum, Germany; 2. Now at Department of Geology and Geophysics, University of Aberdeen, Aberdeen, United Kingdom; 3. German Research Centre for Geosciences GFZ, Section 4.8 Geoenergy, Section 2.2 Geophysical Deep Sounding, Potsdam, Germany; 4. Istituto di Geologia Ambientale e Geoingegneria, Consiglio Nazionale delle Ricerche, Area della Ricerca CNR—ARM3, Milan, Italy; 5. School of Geosciences, Grant Institute, University of Edinburgh, Edinburgh, United Kingdom; 6. Institut für Geophysik, ETH Zürich, Zürich, Switzerland; 7. Institut für Geologie, Mineralogie und Geophysik, Ruhr-Universität Bochum, Bochum, Germany; 8. Fraunhofer-Einrichtung für Energieinfrastruktur und Geothermie IEG, Bochum, Germany *Corresponding author: katrin.loeer@hs-bochum.de; katrin.loer@abdn.ac.uk © Seismological Society of America Volume 91 • Number 6 • November 2020 • www.srl-online.org Seismological Research Letters 3269 Downloaded from http://pubs.geoscienceworld.org/ssa/srl/article-pdf/91/6/3269/5176463/srl-2020022.1.pdf by University of Edinburgh user on 08 November 2020 thermal anomaly could potentially limit the volume of rocks in which secondary permeability may exist. We use three-component (3C) beamforming to extract structural information from ambient seismic noise. 3C beamforming is an array technique, which, like standard beamforming, not only estimates the dominant propagation direction and wavenumber of a recorded wavefield, but in addition determines the polarization of the wavefield by comparing phase shifts across different components (Riahi et al., 2013). As a result, different wave types can be distinguished and their propagation parameters analyzed separately. This allows us, for example, to estimate wavefield composition and surface-wave anisotropy, which is, however, beyond the scope of this study. Here, we consider fundamental mode Rayleigh waves only and extract dispersion curves from frequency–wavenumber (f-k) histograms; these are inverted for a shear-velocity depth profile using a reversible-jump Markov chain Monte Carlo (rj-McMC) algorithm. Although this algorithm is computationally expensive, it has the advantage of providing uncertainties for the velocity profile by finding the distribution of models that are consistent with data. 3C beamforming does not require impulsive (man-made or natural) seismic sources and is thus cheap, flexible, and applicable also in aseismic areas. Whereas cross-correlation-based ambient noise methods typically rely on month-long recordings, from beamforming, we extract stable dispersion curves from only 1 day of seismic noise data. Depending on the array geometry and seismic noise spectrum, the depth sensitivity of 3C beamforming can exceed that of other seismic methods by several kilometers, as we will show in this study. The analysis of four reflection seismic lines recorded across the LHVC, for example, provided 2D velocity maps and seismic sections down to 6 km at the most (Jousset, Ágústsson, et al., 2019). Ambient noise cross-correlation methods applied in the same area, but using a larger array, produce 3D tomographic Figure 1. (a) Simplified geological map of the Los Humeros volcanic complex (LHVC) and surrounding basement, on a shaded relief. The trace of the A-A′ geological cross section of panel (b) is shown. Triangles denote seismic station locations of the dense broadband (DB) network, circles denote geothermal wells. In the upper-right inset, the location of the LHVC within the TransMexican volcanic belt (TMVB) is indicated. (b) A–A′ schematic geological cross section showing the subsurface geometry of the main structures and stratigraphic units. Trace of the geological cross section is shown in panel (a). Modified from Norini et al. (2019). ENE, east-northeast; LH, Los Humeros caldera ring fault; LHh, inferred flexure plane of the Los Humeros trap-door caldera; LP, Los Potreros caldera ring fault; TF: thrust fault; RF, resurgence fault (red lines); WSW, west-southwest. The color version of this figure is available only in the electronic edition. 3270 Seismological Research Letters www.srl-online.org • Volume 91 • Number 6 • November 2020 Downloaded from http://pubs.geoscienceworld.org/ssa/srl/article-pdf/91/6/3269/5176463/srl-2020022.1.pdf by University of Edinburgh user on 08 November 2020 images down to a maximum of 10 km depth (Granados Chavarria et al., 2020; Martins et al., 2020). In a similar manner, a recent local earthquake tomography study provides information only of the upper 3–4 km (Toledo et al., 2020). We show that 3C beamforming provides information to greater than 10 km depth. In the following, we describe geology and available datasets, introduce both 3C beamforming and the rj-McMC inversion algorithm, and summarize our findings in Los Humeros and their implications for SHGSs, in general. Geology of LHVC The LHVC basement is composed of Mesozoic sedimentary rocks involved in the Late Cretaceous–Eocene compressive orogenic phase that generated the Mexican fold and thrust belt (sedimentary basement unit in Fig. 1) (Fitz-Díaz et al., 2017; references therein). The sedimentary basement rests above the Precambrian–Paleozoic crystalline basement of the Teziutlan Massif unit, made of greenschists, granodiorites, and granites (e.g., Suter, 1987; Suter et al., 1997; Ortuño-Arzate et al., 2003; Ángeles-Moreno, 2012; Fitz-Díaz et al., 2017) (Fig. 1a,b). Since the Eocene, the area underwent a limited extensional tectonic phase, associated with northeast-striking normal faults and the emplacement of Eocene–Miocene granite and granodiorite magmatic intrusions (Fig. 1a). The TMVB volcanic activity occurred from 10.5 to 1.55 Ma with the emplacement of fractured andesites, basaltic lava flows, and few volcaniclastic levels (old volcanic succession unit in Fig. 1) (e.g., Yanez and Garcia, 1982; Ferriz and Mahood, 1984; López-Hernández, 1995; Cedillo-Rodríguez, 1997; Carrasco-Núñez, Hernandez, et al., 2017; Carrasco-Núñez et al., 2018). Volcanic activity resumed ∼700 ka ago with the emplacement of the Pleistocene– Holocene LHVC (LHVC unit in Fig. 1) (e.g., Carrasco-Núñez, Hernandez, et al., 2017; Carrasco-Núñez et al., 2018). This volcanic complex represents a basaltic andesite–rhyolite system of two nested calderas, namely the outer Los Humeros caldera and the inner Los Potreros caldera (Carrasco-Núñez, Hernandez, et al., 2017; Calcagno et al., 2018) (Fig. 1a). The LHVC caldera stage occurred between ∼165 and ∼69 ka and consisted of two major ca
10 citations
TL;DR: In this paper, a passive seismic experiment using 25 broadband and 20 short period stations was conducted between September 2017 and September 2018 at Los Humeros geothermal field, an important natural laboratory for superhot geothermal systems in Mexico.
Abstract: A passive seismic experiment using 25 broadband and 20 short‐period stations was conducted between September 2017 and September 2018 at Los Humeros geothermal field, an important natural laboratory for superhot geothermal systems in Mexico. From the recorded local seismicity, we derive a minimum 1‐D velocity model and obtain 3‐D Vp and Vp/Vs structures of Los Humeros. We improved the classical local earthquake tomography by using a postprocessing statistical approach. Several inversions were computed and averaged to reduce artifacts introduced by the model parametrization and to increase the resolution of the investigated region. Finally, the resulting Vp and Vp/Vs structures and associated seismicity were integrated with newly acquired geophysical and petrophysical data for comprehensive interpretation. The recorded seismicity is mainly grouped in three clusters, two of which seem directly related to exploitation activities. By combining new laboratory measurements and existing well data with our Vp model, we estimate possible geological unit boundaries. One large intrusion‐like body in the Vp model, together with neighboring high Vp/Vs anomalies, hints at a region of active resurgence or uplift due to the intrusion of new magma at the northern portion of the geothermal field. We interpret high Vp/Vs features as fluid bearing regions potentially favorable for further geothermal exploitation. Deep reaching permeable faults cutting the reservoir unit could explain fluid flow from a deeper local heat source in the area.
10 citations
Cites methods from "One year of passive seismic monitor..."
...This subnetwork was primarily designed for local microseismicity retrieval (Gaucher et al., 2019), local earthquake tomography, beamforming of ambient noise (Löer et al., 2020), time-reverse imaging (Werner & Saenger, 2018), and autocorrelation techniques (Verdel et al., 2019)....
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...We focused the event detection mainly on Los Potreros caldera (Gaucher et al., 2019) using Python tools based on the ObsPy library (Beyreuther et al., 2010)....
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TL;DR: In this paper, ground movements induced by the 8 February 2016, Mw=4.2 earthquake at the Los Humeros Geothermal Field (Mexico) using Sentinel-1 radar interferometry were investigated.
5 citations
Cites background from "One year of passive seismic monitor..."
...The location of the deformation signal corresponds to the easternmost cluster of seismic events observed between September 2017 and September 2018 (Gaucher et al., 2019) E....
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01 Jan 2020
TL;DR: In this article, the authors analyzed the continuous seismic records to detect the micro-seismicity mainly related to exploitation activities at Los Humeros Volcanic Complex (LHV).
Abstract:
The GEMex* project is a recently finalized European-Mexican collaboration that aimed to improve the understanding of two geothermal fields: Acoculco and Los Humeros Volcanic Complex . These sites are located in the Trans-Mexican Volcanic Belt, a region that hosts numerous active volcanoes and is favorable for geothermal exploitation. Currently, the Los Humeros Volcanic Complex is one of Mexico’s main geothermal systems with an installed capacity of ~95MW. Many studies have been performed at this site since the 70s highlighting several features and characteristics of the shallow subsurface. However a thorough knowledge of structures and behavior of the system at greater depths is still quite sparse. Hence one main objective of the GEMex project was to conduct several geological, geochemical, and geophysical experiments to investigate deeper structures for future development of local and regional geothermal resources.
In this framework, for the period of one year (September 2017 to September 2018), a seismic array consisting of 45 seismic stations was set to record continuously at the Los Humeros Volcanic Complex. In this study we analyzed the continuous seismic records to detect the micro-seismicity mainly related to exploitation activities. After applying a recursive STA/LTA detection algorithm, we assembled and manually picked P- and S- phases of a catalog of about 500 local events. The detected events were mostly clustered around injection wells, with fewer events located close to known structures. We use the retrieved catalog to derive a new minimum 1D velocity model for the Los Humeros site. We then performed a joint inversion to obtain the 3D Vp and Vp/Vs structures of the geothermal field. A post-processing averaging of several inversions was also computed to increase resolution of the investigated region. In this study we will show the derived Vp and Vp/Vs models for the Los Humeros Volcanic Complex to emphasize various underground structures and potentially identify possible variations due to changes in temperature, fluid content, and rock porosity.
*This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 727550 and the Mexican Energy Sustainability Fund CONACYT-SENER, project 2015-04-68074. We thank the Comisión Federal de Electricidad (CFE) for kindly granting the access to the geothermal field for installation and maintenance of seismic stations.
3 citations
01 Jan 2008
TL;DR: In this paper, a tomografia sismica por atenuacion of ondas de coda (Qc - 1 ) in el campo geotermico de Los Humeros, Puebla, se han utilizado 95 sismos locales (Md≤3.6) with profundidades up to 4.0 km, registrados en las estaciones de su red sismICA, durante el periodo de diciembre 1997 a dicemebre 2004.
Abstract: Para realizar la tomografia sismica por atenuacion de ondas de coda (Qc - 1 ) en el campo geotermico de Los Humeros , Puebla , se han utilizado 95 sismos locales (Md≤3.6) con profundidades hasta 4.0 km, registrados en las estaciones de su red sismica, durante el periodo de diciembre 1997 a diciembre 2004. Se utilizo el modelo de retrodispersion simple, filtrados en cuatro rangos de frecuencias (2, 4, 6, y 8 Hz) y una ventana de 5 segundos. Para la representacion en 3D, se utilizo una aproximacion basada en elipsoides que representan dispersion de primer orden. Los resultados muestran que los valores de Qc para las frecuencias utilizadas tienen una dependenci a con la frecuencia de la forma: 06 . 0 86 . 0 12 24 f Qc , donde los valores bajos de Qc fueron observados en la zona de mayor actividad sismica y en la ubicacion de pozos inyectores y productores , mientras que los valores altos se observaron en la periferi a del campo geotermico. Asimismo, la distribucion de la atenuacion Qc - 1 en 3D y 2D muestra que las anomalias de alta atenuacion sismica se ubican en los extremos norte, sur y suroeste de la zona de explotacion actual , y a profundidades mayores a 2.5 km
3 citations
References
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TL;DR: In this article, the same inversion formalism was used to determine hypocenters and one-dimensional (1-D) velocity model parameters, including station corrections, as the first step in the 3D modeling process.
Abstract: The inverse problem of three-dimensional (3-D) local earthquake tomography is formulated as a linear approximation to a nonlinear function. Thus the solutions obtained and the reliability estimates depend on the initial reference model. Inappropriate models may result in artifacts of significant amplitude. Here, we advocate the application of the same inversion formalism to determine hypocenters and one-dimensional (1-D) velocity model parameters, including station corrections, as the first step in the 3-D modeling process. We call the resulting velocity model the minimum 1-D model. For test purposes, a synthetic data set based on the velocity structure of the San Andreas fault zone in central California was constructed. Two sets of 3-D tomographic P velocity results were calculated with identical travel time data and identical inversion parameters. One used an initial 1-D model selected from a priori knowledge of average crustal velocities, and the other used the minimum 1-D model. Where the data well resolve the structure, the 3-D image obtained with the minimum 1-D model is much closer to the true model than the one obtained with the a priori reference model. In zones of poor resolution, there are fewer artifacts in the 3-D image based on the minimum 1-D model. Although major characteristics of the 3-D velocity structure are present in both images, proper interpretation of the results obtained with the a priori 1-D model is seriously compromised by artifacts that distort the image and that go undetected by either resolution or covariance diagnostics.
919 citations
"One year of passive seismic monitor..." refers methods in this paper
...This model was computed using the VELEST software, which applies the methodology described by Kissling et al. (1994)....
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01 Jan 2010
TL;DR: ObsPy as mentioned in this paper is a Python toolbox that simplifies the usage of Python programming for seismologists by providing direct access to the actual time series, allowing the use of powerful numerical array-programming modules like NumPy (http://numpy.mathworks.org) or SciPy(http://scipy.org).
Abstract: The wide variety of computer platforms, file formats, and methods to access seismological data often requires considerable effort in preprocessing such data. Although preprocessing work-flows are mostly very similar, few software standards exist to accomplish this task. The objective of ObsPy is to provide a Python toolbox that simplifies the usage of Python programming for seismologists. It is conceptually similar to SEATREE (Milner and Thorsten 2009) or the exploration seismic software project MADAGASCAR (http://www.reproducibility.org). In ObsPy the following essential seismological processing routines are implemented and ready to use: reading and writing data only SEED/MiniSEED and Dataless SEED (http:// www.iris.edu/manuals/SEEDManual_V2.4.pdf), XML-SEED (Tsuboi et al. 2004), GSE2 (http://www.seismo.ethz.ch/autodrm/downloads/provisional_GSE2.1.pdf) and SAC (http:// www.iris.edu/manuals/sac/manual.html), as well as filtering, instrument simulation, triggering, and plotting. There is also support to retrieve data from ArcLink (a distributed data request protocol for accessing archived waveform data, see Hanka and Kind 1994) or a SeisHub database (Barsch 2009). Just recently, modules were added to read SEISAN data files (Havskov and Ottemoller 1999) and to retrieve data with the IRIS/FISSURES data handling interface (DHI) protocol (Malone 1997). Python gives the user all the features of a full-fledged programming language including a large collection of scientific open-source modules. ObsPy extends Python by providing direct access to the actual time series, allowing the use of powerful numerical array-programming modules like NumPy (http://numpy.scipy.org) or SciPy (http://scipy.org). Results can be visualized using modules such as matplotlib (2D) (Hunter 2007) or MayaVi (3D) (http://code.enthought.com/ projects/mayavi/). This is an advantage over the most commonly used seismological analysis packages SAC, SEISAN, SeismicHandler (Stammler 1993), or PITSA (Scherbaum and Johnson 1992), which do not provide methods for general numerical array manipulation. Because Python and its previously mentioned modules are open-source, there are no restrictions due to licensing. This is a clear advantage over the proprietary product MATLAB (http://www.mathworks.com) in combination with MatSeis (Creager 1997) or CORAL (Harris and Young 1997), where the number of concurrent processes is limited by a costly and restricting license policy. Additionally, Python is known for its intuitive syntax. It is platform independent, and its rapidly growing popularity extends beyond the seismological community (see, e.g., Olsen and Ely 2009). Python is used in various fields because its comprehensive standard library provides tools for all kinds of tasks (e.g., complete Web servers can be written in a few lines with standard modules). It has excellent features for wrapping external shared C or FORTRAN libraries, which are used within ObsPy to access libraries for manipulating MiniSEED (libmseed; http://www.iris.edu/pub/programs) and GSE2 (gse_util; http://www.orfeus-eu.org/Software/softwarelib.html#gse) volumes. Similarly, seismologists may wrap their own C or FORTRAN code and thus are able to quickly develop powerful and efficient software. In the next section we will briefly introduce the capabilities of ObsPy by demonstrating the data conversion of SAC files to MiniSEED volumes, removing the instrument response, applying a low-pass filter, and plotting the resulting trace. We then give an overview on how to access an external C or FORTRAN library from within Python.
799 citations
TL;DR: In this article, the parametric form log A ij = − n log R ij − K ij + ∑ k = 1 106 C k δ ik where Aij = A (mm) for earthquake i on seismograph component j, ik = Kronecker delta, R = hypocentral distance, and n, K, Sl, and Ck are variables determined by regression analysis.
Abstract: Nine hundred fifty-seven maximum zero-to-peak Wood-Anderson amplitudes A (synthesized or recorded) from 40 horizontal-component seismographs (20 sites) with 0 ≲ Δ ≲ 400 km for 106 earthquakes with 18 ≦ log M ≦ 22.3 in central California have been fit in a least-squares sense using the parametric form log A ij = − n log R ij − K R ij − ∑ l = 1 40 S l δ ij + ∑ k = 1 106 C k δ ik where Aij = A (mm) for earthquake i on seismograph component j , δ ik = Kronecker delta, R = hypocentral distance, and n, K, Sl , and Ck are variables determined by regression analysis. The Ck are a magnitude measure, and the Sl are station corrections constrained to have zero average. We find n = 1.018 ± 0.107 and K = 0.00291 ± 0.00070 km−1. Setting n = 1, appropriate for body-wave propagation in homogeneous media, yields K = 0.00301 ± 0.00036 km−1. Following Richter's definition of an ML = 3 earthquake as one for which A = 1 mm at Δ = 100 km and S 1 = 0, we express the local magnitude ML as ML = log A − log A , where -log A = n log ( R /100) + K ( R − 100) + 3. For 30 ≲ Δ ≲ 475 km, the -log A values using n = 1 and K = 0.00301 km−1 are within 0.15 of Richter's values for southern California. For Δ ≲ 30 km, Richter's values are significantly smaller than those obtained here, a result consistent with recent studies of −log A for southern California. Our results suggest that the ML scale as commonly used underestimates the sizes of small shocks that are predominantly recorded at Δ ≲ 30 km.
166 citations
"One year of passive seismic monitor..." refers methods in this paper
...Once the earthquake hypocentre is obtained, a local earthquake magnitude (Mlv) is estimated using the Obspy library (Beyreuther et al. 2010), which applies the formula of Bakun and Joyner (1984)....
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TL;DR: In this article, preliminary 3-D models have been constructed for two sites located in the easternmost region of the Trans-Mexican Volcanic Belt, including Los Humeros and Acoculco, in order to have a coherent geological interpretation of both sites.
Abstract: . As part of the GEMex Project, an on-going European-Mexican effort to develop
geothermal energy from non-conventional sources, preliminary geological
models have been constructed for two sites located in the easternmost region
of the Trans-Mexican Volcanic Belt. The first site, Los Humeros, which has
produced geothermal electricity for decades, is investigated for its probable
superhot geothermal resources. The second site, Acoculco, is a less known but
promising area where application of an Enhanced Geothermal System is being
studied. In order to have a coherent geological interpretation of both sites,
preliminary 3-D models were constructed in a collaborative manner by European
and Mexican partners. These models are based on data available at the start
of the project, including geological maps, cross-sections and well logs. The
data were mainly provided by the Comision Federal de Electricidad (CFE),
and the Mexican Centre for Innovation in Geothermal Energy (CeMIE-Geo
consortium). A regional model was developed for each site and an additional
local model was constructed for Los Humeros. The preliminary geological
models serve as a framework for GEMex work on heat-transport and fluid-flow
simulations; they will be updated and refined during the project, using new
data and interpretations from ongoing and future field work on geology,
geophysics, and geochemistry.
36 citations
"One year of passive seismic monitor..." refers background in this paper
...It is rather a simplistic view within this volcanic geomorphology, as described by Calcagno et al. (2018), but this initial choice is motivated by the fact that several tomography techniques will be applied to better describe the velocity model in 3D....
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...Twenty-five wells are producing 6 Mt of steam every year from the 2-km deep reservoir (Calcagno et al. 2018)....
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...Geologically, the Los Humeros volcanic system is a Pleistocene basalt-andesite-rhyolite system (Calcagno et al. 2018)....
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01 Jan 2008
TL;DR: In this article, the authors analyze the distribution of sism ocurridos in the campo geotermico de Los Humeros, Puebla, Mexico, during the period of 1997-2004.
Abstract: Se analiza la distribucion en superficie y en profundidad de los sism os ocurridos en el campo geotermico de Los Humeros, Puebla (Mexico), durante el pe riodo 1997-2004. Los datos corresponden a 95 sism o s registrados por m a s de cinco estaciones perm anentes y temporales instaladas por la Com i sion Federal de Electricidad y el Instituto de Ingeni eria de la Universidad Nacional Au tono m a de Mexico, cuyas m a gnitudes de duracion son m e nores o iguales a 3.6 Md y pr ofundidades focales que no sobrepasan los 4.0 km . Asim ism o , se realizaron m ecanism o s focales simples y de in version de tensor de m o m e nto, y se com p aro el nu m e ro de sism os registrados por dos estacion es de la red perm anente (n u m eros S05, S06) con la inyeccion de agua y la produccion de vapor durante cierto tie m po. Los resultados en superficie y en profundidad muestran activid ad s i smica en la zo na norte del cam po, alrededor de los pozos inyectores I29 (pozo H-29) e I38 (pozo H-38), m i entras que los mecanism o s focales s i m p les y de tens or de m o mento evidencian esfuerzos de origen heterogeneo, sugiriendo qu e parte de la actividad sism ica ocurrida en Los Hu m e ros puede haber sido “inducida” principalm ente por el proceso de iny eccion de agua al subsue lo del campo geoterm i co
19 citations
"One year of passive seismic monitor..." refers background or methods in this paper
...Previous studies (Lermo et al. 2007; Urban and Lermo 2013) highlight the occurrence of local seismic activity in the Los Humeros geothermal field, mainly in the exploited Los Potreros caldera zone....
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...Although Lermo et al. (2007) proposed a 1D P-wave velocity model for the zone, it was decided to use a socalled minimum 1D-velocity model....
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...Lermo et al. (2007) observe a seismogenic zone located to the east of the northernmost cluster we see, but they do not observe activity close to the other three clusters....
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...The analyses are based on a telemetered permanent seismic network of six three-component stations installed by CFE in 1997, and on temporary networks installed in the area for the sake of the studies (Gutiérrez-Negrín and Quijano-León 2004; Lermo et al. 2007)....
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