A preliminary seismic travel time tomography beneath Ecuador from data of the national network

Araujo, Sebastián; Valette, Bernard; Potin, Bertrand; Ruiz, Mario

doi:10.1016/j.jsames.2021.103486

Cited by 9 publications

(8 citation statements)

References 48 publications

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“…This difference in subduction angle, combined with the convex shape of the continental margin, has induced a slab exure beneath the southern part of the Ecuadorian Andes (Fig. 1a; Yepes et al, 2016;Portner et al, 2020;Araujo et al, 2021). Furthermore, the oblique convergence of the Nazca Plate caused the motion of the northwestern edge of the South American plate known as the North Andean Sliver (Fig.…”

Section: Ecuadorian Geological Settingmentioning

confidence: 99%

See 1 more Smart Citation

Blossoming of the Pleistocene volcanism in the Ecuadorian Andes: a review based on new and recent geochronological data

Santamaria,

Bablon,

Quidelleur

et al. 2024

Preprint

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The Ecuadorian arc is composed of an unusually high number of volcanoes organized as along-arc alignments and across-arc clusters, over a relatively small area. Although several geochronological studies were carried out in the past three decades, the eruptive history of the central zone of the arc remained poorly documented, preventing the analyses of volcanism initiation of the whole arc. In this study, we present new K-Ar ages obtained from this central area, referred as the Quito segment. These results were then included in an updated comprehensive geochronological database including about 250 ages, allowing us to describe, at the arc scale, the spatial and temporal development of Quaternary volcanic activity in Ecuador. About eighty Quaternary volcanoes are identified in the Ecuadorian Andes, amounting to 45 volcanic complexes with radiometric ages and/or identified as active or potentially active. The volcanic arc developed in three stages marked by increases in the total number of active volcanoes. During the oldest Plio-Early Pleistocene stage, the documented volcanic activity was mostly concentrated in the Eastern Cordillera of the Quito segment, with minor effusive eruptions in the southern Back-Arc. Since ~ 1.4 Ma, the activity spread to the surroundings of the Quito segment and new edifices also appeared in the Western Cordillera and the Inter-Andean Valley. Towards the end of this intermediate stage (i.e., ~ 800 ka), volcanism occurred in isolated areas to the north and south of the Inter-Andean Valley. Finally, the late and current stage was characterized by a remarkable increase in volcanic activity since ~ 600 ka. Approximately 50 volcanoes were active during this stage. The spatial distribution of the Ecuadorian arc volcanism seems to be guided by deep mechanisms and old crustal tectonic structures from the Western Cordillera, whereas the neotectonics seem to influence the development of stratovolcanoes. In addition, we note that the spatial and temporal evolution of volcanism highlights the influence of the Carnegie Ridge and the thermal regime anomaly of the young Nazca crust on the increase of volcanic activity in Ecuador.

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Section: Ecuadorian Geological Settingmentioning

confidence: 99%

“…arc, probably due to the slab thermal conditions(Yepes et al, 2016;Hayes et al, 2018;Araujo et al, 2021). Since at least ~ 2.5 Ma, an intense volcanism seems to be present mainly in the Quito segment, which is above the projection of the Carnegie Ridge.…”

mentioning

confidence: 99%

Blossoming of the Pleistocene volcanism in the Ecuadorian Andes: a review based on new and recent geochronological data

Santamaria,

Bablon,

Quidelleur

et al. 2024

Preprint

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“…Since the main motivation of FWI is to refine the spatial resolution of tomographic images, we must therefore use correlation kernels that decay less rapidly at high wavenumbers, such as exponential (or Laplacian) kernels (e.g. Oliver 1998;Trinh et al 2017;Araujo et al 2021). Since Gaussian or exponential kernels have broad support, convolving these filters on a large 3-D grid can be time-consuming and difficult to implement when the computational grid is distributed with domain decomposition.…”

Section: And Cmentioning

confidence: 99%

“…Oliver 1998;Tarantola 2005;Trinh et al 2017), an interesting property that has been already exploited to regularize tomographic inversions (e.g. Potin 2016;Araujo et al 2021).…”

Section: And Cmentioning

confidence: 99%

A consistent multiparameter Bayesian full waveform inversion scheme for imaging heterogeneous isotropic elastic media

Kan

Chevrot

Monteiller

2022

Geophysical Journal International

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Summary The inversion of complete seismic waveforms offers new perspectives to better constrain the elastic properties of Earth’s interior. However, models of density and seismic velocities obtained from full waveform inversions are generally characterized by very different and uneven spatial resolutions. Because the three-dimensional structure of the Earth represents small deviations from average reference Earth models, the absolute values of density, VP and VS in the Earth are strongly correlated. Here, we exploit this strong correlation between model parameters as a priori information introduced into a new full waveform inversion algorithm, by considering a non-diagonal 3-D model covariance matrix in which the spatial correlations of elastic properties are described with an exponential covariance function. The inverse of such a model covariance matrix is easy to compute, and we thus have all the ingredients to construct a consistent Bayesian full waveform inversion scheme. We show that taking into account the correlations between density and seismic velocities can lead to dramatic improvements on the reconstructed models of density, seismic velocities, and VP/VS ratio. This new imaging approach opens new perspectives for refining tomographic images of density and seismic velocities in the lithosphere and upper mantle on a regional scale by full waveform inversion of teleseismic body waves.

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“…Among the most well-known class a) seismic nests around the world are the Bucaramanga nest in Colombia, the Vrancea nest (VRN) in Romania, and the Hindu-Kush nest (HKN) in Afghanistan. Furthermore, various studies have identified other possible seismic nests, such as the Jujuy seismic nest in the Chile -Argentina border (Valenzuela-Malebrán et al, 2022), in Fiji (Schneider et al, 1987), and Ecuador (Araujo et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Partially non-ergodic ground motion model for the Bucaramanga seismic nest in Northern South America (NoSAm Nest GMM)

Pájaro,

Carlos,

Vicente

et al. 2023

Preprint

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The Bucaramanga seismic nest has the highest concentration of seismic events with magnitudes over 4.8 worldwide. Despite the nest depth, these events play a crucial role in the seismic hazard assessment for several cities in northern South America (NoSAm), particularly those situated close to their epicenters. Moreover, these earthquakes are widely felt across the country, even hundreds of kilometers away from the nest. This paper assesses the performance of commonly used subduction intra-slab Ground Motion Models (GMMs) in predicting the updated nest database gathered and processed by the Colombian Geological Survey. This analysis confirms the necessity of a partially non-ergodic ground motion model for estimating the spectral acceleration produced by Bucaramanga nest earthquakes in northern South America. The GMM presented herein is the first model developed specifically for seismic nests in the region and is conceived as a regionalization of the recent NGA-Sub Abrahamson and Gülerce (2022) GMM. Additionally, we provide estimates of the variance components at both the earthquake and station levels and compare the developed GMM with the spectral accelerations recorded for typical earthquakes, for the highest magnitude earthquake in the database, and for the most recent Bucaramanga nest earthquake having a moment magnitude over 5.

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A preliminary seismic travel time tomography beneath Ecuador from data of the national network

Cited by 9 publications

References 48 publications

Blossoming of the Pleistocene volcanism in the Ecuadorian Andes: a review based on new and recent geochronological data

Blossoming of the Pleistocene volcanism in the Ecuadorian Andes: a review based on new and recent geochronological data

A consistent multiparameter Bayesian full waveform inversion scheme for imaging heterogeneous isotropic elastic media

Partially non-ergodic ground motion model for the Bucaramanga seismic nest in Northern South America (NoSAm Nest GMM)

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