| Titre | Fault parameters of the Nisqually earthquake determined form moment tensor solutions and the surface deformation from GPS and InSAR |
| |
| Auteur | Bustin, A; Hyndman, R D ; Lambert, A; Ristau, J; He, J; Dragert, H; Van der
Kooij, M |
| Source | Bulletin of the Seismological Society of America vol. 94, no. 2, 2004 p. 363-376, https://doi.org/10.1785/0120030073 |
| Année | 2004 |
| Séries alt. | Commission géologique du Canada, Contributions aux publications extérieures 2003031 |
| Éditeur | Seismological Society of America (SSA) |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1785/0120030073 |
| Media | papier; en ligne; numérique |
| Formats | pdf |
| Province | Colombie-Britannique |
| SNRC | 82; 92; 93D; 93E; 93L; 102; 103A; 103B; 103C; 103F; 103G; 103H; 103I; 103J; 103K |
| Région | le sud de la Colombie-Britannique; coastal British Columbia; Océan Pacifique; Washington State; Puget Sound; Oregon |
| Lat/Long OENS | -134.0000 -114.0000 55.0000 40.0000 |
| Lat/Long OENS | -134.0000 -114.0000 55.0000 40.0000 |
| Sujets | secousses séismiques; études séismiques; mécanismes de tremblement de terre; failles; déformation; déplacement; imagerie par satellite; subduction; affaissement; epicentres; mesures des mouvements;
établissement de modèles; panneau orienté vers le bas; géodésie; géodésie par satellite; séismologie; solutions dans un plan de faille; Tremblement de terre de Nisqually ; Plaque de Juan de Fuca; Zone de subduction de Cascadia ; géophysique |
| Illustrations | croquis cartographiques; mécanismes au foyer; tableaux; sismogrammes; séries chronologiques; images satellitaires; modèles altimétriques numériques; profils; modèles 3D; coupes transversales;
blocs-diagrammes |
| Programme | CRSNG Conseil de recherches en sciences
naturelles et en génie du Canada |
| Programme | GEOIDE La Géomatique pour des
interventions et des décisions éclairées |
| Diffusé | 2004 04 01 |
| Résumé | (disponible en anglais seulement)
The magnitude 6.8 Nisqually earthquake occurred on 28 February 2001 at a depth of 50-60 km within the subducting Juan de Fuca plate. The fault parameters are
estimated from moment tensor solutions and by comparing the surface displacements from Global Positioning System (GPS) data and from satellite interferometry, with predictions from elastic deformation models. The simple deformation model calculates
the coseismic surface displacements caused by an earthquake on an extensional rectangular fault in a uniform half-space. Continuous GPS stations within 200 km of the epicenter resolved horizontal displacements as great as 9 mm (210°) and vertical
displacements as great as 13 mm of subsidence near the epicenter. The near-vertical displacements were also determined from a differential interferogram created from synthetic aperture radar (InSAR) data from RADARSAT, the only satellite data
available for the event. A maximum vertical subsidence of approximately 20 mm is observed 30 km east of the epicenter. The GPS, InSAR, and moment tensor solutions provide a consistent solution for the rupture parameters of the Nisqually earthquake.
The fault has a strike of 180° and a dip of 20° and is centered at 47.10° N and 122.67° W (4 km east and 6 km south of the epicenter) or has a strike of 360° and a dip of 70° and is centered at 47.10° N and 122.69° W (2 km east and 6 km south). The
trade-off between fault area and rupture displacement is not resolved by our data, but a good fit is found with the main rupture having an area of 230 km2 and an along-strike length of 23 km and downdip width of 10 km. The rupture area is centered at
a depth of 51 km with a scalar moment of 2.0 × 1019 N m and, with the given area, an average rupture displacement of 1.4 m. To refine the interpretation of the GPS and InSAR data, a 3D heterogeneous numerical model was generated having realistic
shear moduli structure, a 3D model of the subducting slab, and a spherical Earth. The results are similar to those from the half-space model, but there is significant refinement with a deeper rupture center at 60 km. |
| GEOSCAN ID | 214322 |
|
|