| Titre | A crustal focal mechanism catalog for northern Chile: initial results |
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| Auteur | Herrera, C; Cassidy, J F ; Dosso, S E; Block, W; Sippl, C |
| Source | SSA 2020 Annual Meeting
; 2020 p. 1  Accès ouvert |
| Liens | Online - En ligne
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| Image |  |
| Année | 2020 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20190359 |
| Éditeur | Seismological Society of America |
| Réunion | Seismological Society of America 2020 Annual Meeting; Albuquerque, NM; US; avril 27-30, 2020 |
| Document | site Web |
| Lang. | anglais |
| Media | en ligne; numérique |
| Formats | html; pdf |
| Région | Andes |
| Lat/Long OENS | -84.0000 -56.0000 -18.0000 -24.0000 |
| Sujets | séismologie; secousses séismiques; risque de tremblement de terre; risque sismique; sismicité; magnitudes des séismes; réseau sismique; ondes sismiques; spectres d'amplitude; géologie du substratum
rocheux; caractéristiques structurales; failles; cadre tectonique; zones de subduction; tendances structurelles; détermination des contraintes; géophysique; géologie structurale; Sciences et technologie; Nature et environnement |
| Programme | Géoscience pour la sécurité publique Risques géologique du tremblement de terre |
| Diffusé | 2020 04 01 |
| Résumé | (disponible en anglais seulement)
Chile experiences considerable seismic hazard from interplate, intraplate and crustal earthquakes. Due to their large magnitudes and frequent occurrence in the
Nazca subduction zone, interplate and intraplate earthquakes have been widely studied with broadband and strong motion networks. However, the smaller-magnitude crustal seismicity has been studied much less, and the lack of sufficiently dense seismic
networks over most of the country makes comprehensive studies of crustal events very challenging.
In northern Chile, the interseismic gap since the last giant thrust earthquake in 1877 has motivated the deployment of several temporary and
permanent seismic networks since the early 2000s, thus providing new opportunities to carry out seismological studies in the area, especially between latitudes 18°S and 24°S.
We select more than 800 ML greater than or equal to 3.0 crustal
earthquakes that occurred between 2005 and 2018, reported in two recently-published earthquake catalogs for the area, and calculate their focal mechanisms using P-wave polarities and S/P amplitude ratios from broadband and short-period waveform data
recorded by local stations.
Our initial results show a variety of faulting geometries, with some trends becoming evident. Several offshore crustal events show north-south strike with thrust mechanisms, indicating strong influence of the main plate
subduction. However, several onshore events near 21°S show a clear east-west strike, with north-south horizontal pressure axes, which may indicate the existence of additional local tectonic features in compressive regime. Further inland, persistent
seismicity occurs in the Andes mountains in a small area near latitude 19.7°S, which could be related to the 2001 Mw 6.3 Aroma crustal earthquake.
Our compilation of crustal-earthquake results for northern Chile can provide clues to local and
regional faulting patterns, and serve as a basis for crustal stress mapping studies in the region. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Cette étude examine le champ de stress générateur de tremblement de terre le long de toute la zone de subduction du Chili. Ceci est accompli en
déterminant le mécanisme focal (style de rupture) des tremblements de terre récents et bien enregistrés. L'objectif est de cartographier le champ de contraintes au Chili, pour des applications dans la zone de subduction (similaire) du sud-ouest de la
Colombie-Britannique, afin de mieux évaluer les risques de tremblement de terre au Canada. |
| GEOSCAN ID | 321487 |
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