Mi trabajo de investigación dentro del campo de la Sismología se ha dirigido en los últimos años al estudio del interior de la Tierra y de la corteza. Dentro de esta área he trabajado temas sobre fenómenos sísmicos asociados a los sismos lentos (no emiten sacudidas rápidas), como son el análisis de sismos de muy baja frecuencia (VLF), tremor tectónico (TT) y anisotropía sísmica usando señales de TT. Asimismo, trabajo en temas de estructura de velocidades sísmica de la corteza usando la técnica de tomografía. También he dedicado tiempo al estudio de la fuente sísmica, tales como mecanismos focales y su geometría de procesos de ruptura.

Lineas de investigación.

-Anisotropía sísmica.

-Tomografía Sísimica.

-Fuente Sísmica.

Educación.

Física, Facultad de Ciencias, Universidad Nacional Autónoma de México (UNAM).

Maestría en Ciencias (Sismología), Instituto de Geofísica, UNAM

Doctorado en Ciencias (Sismología), Instituto de Geofísica, UNAM.

Estancia posdoctoral, Universidad de California Riverside, Riverside, CA, EE. UU.

Contacto: ehuesca@gmail.com

Publicaciones Relevantes.

Eduardo Huesca-Pérez and Allen Husker, Shallow travel-time tomography below southern Mexico, Geofísica internacional (2012) 51-3: 281-291

Huesca-Pérez, E., and A. Ghosh (2015), Crustal anisotropy from tectonic tremor under Washington State in the Cascadia. Geophys. Res. Lett., 42, 2228–2234. doi: 10.1002/2014GL062614.

Huesca-Pérez, E., R. W. Valenzuela, and R. Ortega (2016), Crustal anisotropy from tectonic tremor in Guerrero, Mexico, Geochem. Geophys. Geosyst., 17, 2323–2335, doi:10.1002/2016GC006358.

Huesca-Pérez, E., R. Ortega, and R. W. Valenzuela (2017), Continental crust anisotropy measurements from tectonic tremor in Cascadia, J. Geophys. Res. Solid Earth, 122, 3835–3851, doi:10.1002/2017JB013983.

Eduardo Huesca-Pérez, Raúl W Valenzuela, Dana Carciumaru, Roberto Ortega, Edahí Gutiérrez, Enrique Cabral-Cano, Allen Husker (2019), Margin-wide continental crustal anisotropy in the Mexican subduction zone, Geophysical Journal International, Volume 217, Issue 3, Pages 1854–1869, https://doi.org/10.1093/gji/ggz121

Eduardo Huesca-Pérez, Edahí Gutierrez-Reyes, Raúl W. Valenzuela, Allen Husker & Sergio Mayer (2021). 3-D travel-time tomography of southernmost Baja California Peninsula. Journal of South American Earth Sciences, Volume 105, January 2021, 102966

Gerardo León Soto, Raúl W Valenzuela, R Arceo, Eduardo Huesca-Pérez, Ricardo Vazquez Rosas (2021). Teleseismic measurements of upper mantle shear wave anisotropy in the Isthmus of Tehuantepec, Mexico, Geophysical Journal International, Volume 227, Issue 3, December, Pages 1784–1794, https://doi.org/10.1093/gji/ggab301

Gutierrez-Reyes, E., and E. Huesca-Pérez (2022). Calculation of Maximum earthquake accelerations in a semi-empirical way for southern Gulf of California extensional province, Mexico. Natural Hazards. https://doi.org/10.1007/s11069-022-05297-9.

Huesca-Pérez, E., E. Gutierrez-Reyes, and L. Quintanar (2022). Seismic Source Processes of 25 Earthquakes (Mw > 5) in the Gulf of California, Bull. Seismol. Soc. Am., 1–20, doi: 10.1785/0120210218

Tomografía 3-D en la punta sur de la península de Baja California.

Como parte del trabajo desarrollado en la Unidad, se elaboró una tomografía con tiempos de propagación de ondas primarias (P), secundarias (S) y su cociente Vp/Vs en el extremo sur de la península de Baja California. La imagen tomográfica obtenida, revela con mucho detalle las heterogeneidades de la estructura sísmica de velocidades del bloque de Los Cabos. Las imágenes muestran que la corteza, en general, es de velocidad lenta para ambas ondas P y S bajo la península hasta una profundidad de unos 25 km. Particularmente lentas son las ondas bajo la Sierra de la Laguna y en las inmediaciones de la costa del Golfo de California. Velocidades bajas también son detectadas dentro del Golfo cerca de la costa mientras velocidades rápidas están presentes lejos de la costa. Se observa una alternancia entre entre los cocientes de Vp/Vs en toda la zona de estudio. Estas velocidades sísmicas lentas pueden ser explicadas debido a que la corteza se encuentra muy fracturada por diversos sistemas de fallas (V. Gr. falla de San José del Cabo, falla de Los Barriles) y sobre saturada de fluidos junto con un flujo intenso de calor que es manifestado en superficie como actividad geotérmica (V. Gr. manantiales calientes dispersados por todo el bloque). Estas velocidades de ondas de cuerpo lentas coinciden con la existencia de manto astenosférico atrapado entre la corteza y un remanente de una peleoplaca subducida y desacoplada de la superficie que ha sido ampliamente reportada por múltiples investigadores (V. Gr. Di Luccio et al. (2014)). Esta porción de manto emparedada entre la corteza y la paleoplaca subducida podría estar químicamente empobrecida y/o seca inhibiendo el desarrollo de actividad volcánica intensa en esta zona de la península.

Interpretation of low velocity anomalies observed under the Los Cabos block. Composite cartoon showing (top, above 40 km) the S-wave tomography image obtained in this study (slice at 50 km of figure 7 panel b) and (bottom, below 40 km) the interpretation of the S-wave velocity structure determined by Di Luccio et al. (2014) (see figure 9 of their paper). Vertical scale differs above and below 40 km. An asthenospheric mantle wedge (yellow patch) is found between the thinned continental crust and the detached Magdalena slab remnant (blue patch) and drives heat flow from the mantle to the crust (red arrows). Crustal faults are fluid-saturated. Both, the high heat flow and the presence of fluids lead to the low P- and S-wave velocities, as well as the low Vp/Vs ratio, observed under the southern tip of the peninsula. Fault dips taken from Arango-Galván et al. (2015) and Munguía et al. (2006). Position of Moho (orange solid line) from Persaud et al. (2007). From Huesca-Pérez et al (2021).

Modelos de Ruptura para el Golfo de California.

The Gulf of California (GoC) is a complex tectonic boundary that has been instrumented in the past several decades to record broadband seismograms. This volume of data has allowed us to study several source parameters systematically. Before, only a few source parameters of earthquakes greater than magnitude five had been studied in the GoC area. We re-examined the focal mechanisms of several earthquakes in the southern GoC that occurred over the last 20 yr using local–regional distance broadband seismograms. These focal mechanisms were then used as input data to retrieve the time–space history of the rupture for each earthquake. This work contributes to the study of 25 rupture-proc- ess models computed with the method proposed by Yagi et al. (1999). Taken From Huesca-Pérez et al. (2022).

Rupture-process models of 25 earthquakes in the Gulf extensional province. The inversions were obtained using the Yagi et al. (1999) algorithm. In addition, focal mechanism used is plotted next to the models. The red quadrants on focal mechanism plots represent compressions. The blue lines indicate the position of the plane used for the inversion. From Huesca-Pérez et al. (2022).
Modelos de procesos de ruptura obtenidos para la provincia extensional del Golfo de California. Los colores brillantes representan los lugares sobre el plano de falla donde existe mayor desplazamiento durante el proceso de ruptura de un sismo. Las barras azules muestran la orientación de los planos de falla mostrados. Las “pelotas de playa” o los mecanismos focales representan la orientación, el buzamiento y la cinemática de cada plano de falla mostrado (círculos con cuadrantes rojos que representan las compresiones). La figura fue tomada de Huesca-Pérez et al. (2022).

Continental Crust Anisotropy measurements from tectonic tremor in Cascadia.

We present new observations of crustal anisotropy in the southern Cascadia fore arc from tectonic tremor. The abundance of tremor activity in Oregon and northern California during slow-slip events offers an enormous amount of information with which to measure and analyze anisotropy in the upper brittle continental crust. To accomplish this, we performed analyses of wave polarization and shear wave splitting of tectonic tremor signals by using three component broadband seismic stations. The splitting times range between 0.11 and 0.32 s and are consistent with typical values observed in the continental crust. Fast polarization azimuths are, in general, margin parallel and trend N-S, which parallels the azimuths of the maximum compressive stresses observed in this region. This pattern is likely to be controlled by the stress field. Comparatively, the anisotropic structure of fast directions observed in the northern section of the Cascadia margin is oblique with respect to the southern section of Cascadia, which, in general, trends E-W and is mainly controlled by active faulting and geological structures. Source distribution analysis using a bivariate normal distribution that expresses the distribution of tremors in a preferred direction shows that in northern California and Oregon, the population of tremors tends to distribute parallel to fast polarization azimuths and maximum compressive stresses, suggesting that both tremor propagation and anisotropy are influenced by the stress field. Results show that the anisotropy reflects an active tectonic process that involves the northward movement of the Oregon Block, which is rotating as a rigid body. In northern Cascadia, previous results of anisotropy show that the crust is undergoing a shortening process due to velocity differences between the Oregon Block and the North America plate, which is moving more slowly with respect to the Oregon Block, making it clash against Vancouver Island. From Huesca-Pérez et al (2017).

Cascadia margin comparison maps. (a) Fast wave directions (solid black and colored bars) centered on stations (red inverted triangles) along with Holocene-Pleistocene faults from http://earthquake.usgs.Gov/hazards/qfaults/ (red sinuous lines) and seismicity registered in the region (ANSS catalog). (b) Fast wave directions along with the distribution of TT activity (yellow dots). In Figure 7b, maximum compressive stress rakes are plotted as blue bars [Heidbach et al., 2008] and green bars [Balfour et al., 2011]. In both panes, the parallel bold red lines enclosed by opposite red arrows show
the crustal area subjected to N-S compression and crustal shortening. The magenta bold arrows pointing northward indicate the direction of movement of the Oregon Block, according to Wells and Simpson [2001]. Taken From Huesca-Pérez et al (2017).

Twenty-four-hour example plot of polarization attributes and anisotropic parameters computed for central
Oregon station ALP0. The data were recorded on 10 September 2009. Each panel depicts different information: (a) split-
ting times, δt (black dots); (b) fast polarization directions, φ (green dots); (c) back azimuths (pink dots); (d) ray angles (gray dots); (e) the differences between normalized eigenvalues (blue dots); (f) the east component of the
seismogram; and (g) RMS amplitude. The red dots for splitting times and fast polarization panels indicate the final selected
measurements for this day after applying the polarization criterion. From Huesca-Pérez et al (2017).

Crustal anisotropy from tectonic tremor in Guerrero, Mexico

We present new shear wave anisotropy measurements in the continental crust in northern Guerrero obtained from tectonic tremor. Measurements of crustal anisotropy had not been performed in this area due to the lack of seismicity. However, tectonic tremor activity is abundant and offers an opportu- nity to determine anisotropy parameters. Polarization and splitting analyses were performed using broad- band three-component seismograms. Results show that splitting times range between 0.07 and 0.36 s. These values are similar to the splitting magnitudes typically observed in the continental crust. The state of stress in the continental crust was investigated by inverting focal mechanisms determined in this study, and also from previous structural geology studies. Unfortunately, no stress measurements were possible in the area where tectonic tremor occurs. It was determined that, to the south of the study area, near the Pacific coast, and to the north, in the volcanic arc, the maximum compressive stress shows a general E-W trend. The fast polarization directions are oriented NE-SW and are oblique to the observed maximum compressive stress surrounding the study area. Thus, the relationship between the maximum compressive stress and the observed anisotropic pattern cannot be conclusively established. Several factors such as nonlinear strain in the continental crust as a result of Slow Slip Events, variations of pore fluid pressure, deep crustal mineral- ogy, and/or upper crust foliations and schistosity could be inducing the observed anisotropy pattern. In general, the fast axes tend to parallel the regional Laramide and Tertiary folds-and-thrusts which strike NNE-SSW. This system of folds-and-thrusts is highly foliated in low-grade schist and seems likely to control the anisotropic structure observed within the tectonic tremor region in Guerrero. From Huesca-Pérez et al (2016).

Polarization parameters obtained for station APAX for the TT episode of late February and early March 2010. The plot starts on 26 February at 00:00:00, and illustrates the performance of the analysis when tremor is not present (first 30 h) and once tremor has started (after 30 h). Each plot shows different parameters obtained. From top to bottom: splitting times (dt); fast polarization directions (u); back azimuths; ray angles; the differences between normalized eigenvalues (k(2)/k(1) 2 k(3)/k(1)); and the north component of the seismogram and RMS amplitude. The analysis was performed by cutting the seismograms into 1 min long windows. The beginning of the TT is marked by a huge increase in the RMS amplitude at hour 30. The red dots for the splitting time and fast polarization direction plots indicate the final selected measurements. Red dots in ray angle and N3-N2 plots are the values that satisfy the respective criterion. From Huesca-Pérez et al. (2016).

Anisotropy results (pink bars) along with major geological faults (black solid lines) and thrusts (black lines with triangles). Gray-dotted line is the inferred Chacalapa/La Venta left lateral strike-slip fault [Centeno-Garc􏰀ıa et al., 2008] Most of the anisotropy measurements in the present study were made within the Mixteca Terrane, which is surrounded and cut by several thrusts and folds created during the Laramide orogeny and Tertiary deformations. Blue solid lines show the direc- tion of maximum compressive stress taken from the World Stress Map Project [Heidbach et al., 2008]. Red solid bar represents the maximum compressive stress computed in this study using focal mechanisms from Pacheco and Singh [2010] and inverted using the method of Michael [1987]. Dark green bar is the orienta- tion of the P axis from focal mechanism 17. Bright green bar is the maximum compressive stress from structural data reported by Ratschbacher et al. [1991]. Geological faults were drawn from the work of Cerca et al. [2004] and Silva-Romo [2008] for the Mixteca Terrane, and from Centeno-Garc􏰀ıa et al. [2008] for the Teloloapan and Arcelia areas. From Huesca-Pérez et al. (2016).

Margin-wide continental crustal anisotropy in the Mexican subduction zone

We present new shear wave anisotropy measurements in the continental crust along the Mex- ican subduction zone obtained from tectonic tremor. The new measurements were made in the states of Jalisco, Colima, Michoaca ́n and Oaxaca. To make a complete analysis of the anisotropic crustal structure, we also include previous measurements reported in Guerrero using tremor signals. Since tectonic tremor is abundant along the Mexican subduction zone, it offers an opportunity to determine anisotropy parameters in this region. Polarization and splitting analyses were performed using broad-band, three-component seismograms. Results show that splitting times range between 0.07 and 0.34 s. These values are similar to the splitting magnitudes typically observed in the continental crust. Fast polarization azimuths are variable in Jalisco, Colima and Michoaca ́n, but some of them tend to align with the regional stress field (margin-normal and maximum horizontal compressive stresses). On the other hand, the fast axes at the remaining stations are margin parallel, suggesting that in this case anisotropy could be controlled by active crustal faulting or geological structures. In Oaxaca, fast polarization directions tend to align with Tertiary inactive faults and are oblique with respect to the local stress field, which suggest that anisotropic geological structures are the source of anisotropy.

Key words: Composition and structure of the continental crust; North America; Seismic anisotropy; Continental margins: convergent; Crustal structure; Rheology: crust and lithosphere.

Regional map of southern Mexico showing fast wave directions obtained with TT signals along the Mexican subduction zone (solid pink bars). Black bars represent the maximum horizontal compressive stresses reported by Heidbach *et al.* (2008), and by Huesca-Pe ́rez *et al.* (2016). The two green bars in the map are the maximum horizontal compressive stresses obtained by inversion in this study using the method of Michael (1987) and focal mechanisms from Pacheco *et al.* (1999, 2003). Dashed lines represent iso-depths to the subducted Rivera and Cocos plates (Pardo & Suárez 1995). From Huesca-Pérez et al (2019).

The 23-h plot of anisotropic parameters and polarization attributes computed for central Oaxaca State station TXIG. The data were recorded on2013 March 18. Each panel displays different information computed on 1-min-long windows: (a) splitting times, δt (black dots);(b) fast polarization azimuths,φ (purple dots); (c) backazimuths (brown dots); (d) ray angles (grey dots); (e) the differences between normalized eigenvalues (λ(2)/λ(1)—λ(3)/λ(1)) (blue dots);(f) the east–west component of seismogram; and (g) rms amplitude. The red dots for splitting times and fast polarization panels indicate the final selected measurements for this day after applying the polarization criterion. From Huesca-Pérez et al (2019).

Southern Baja California Peninsula Tectonics along with its seismicity.

Modern tectonic configuration of the Gulf of California extensional province. The red line indicates the boundary between North America and the Pacific plates; this is the boundary where the relative motion is taking place. Two stalled microplates are shown and countered by gray lines: The Guadalupe (Gua) and Magdalena (Mag) microplates that now are part of the Pacific plate. Regional seismicity is reported by Servicio Sismológico Nacional (SSN, National Seismological Service) for the period 1901–2021. The color scale represents the hypocenters depths. The inactive plate boundaries (gray lines) are Tosco—Abreojos fault (TAF), Gua fracture zone (GFZ), and Shirley fracture zone (SFZ). The blue arrows represent the absolute plate motions of the Pacific and North America, whereas the black arrows show the relative plate motions as described by the model NUVEL1A (DeMets and Dixon, 1999). The red inverted triangles represent the seismic stations employed. Inset map shows the region of study (red rectangle). From Huesca-Pérez et al. (2022).