| Titre | Changes in Physical Properties of the Nankai Trough Megasplay Fault Induced by Earthquakes, Detected by Continuous Pressure Monitoring |
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| Auteur | Kinoshita, C; Saffer, D; Kopf, A; Roesner, A; Wallace, L M; Araki, E; Kimura, T; Machida, Y; Kobayashi, R; Davis, E ; Toczko, S; Carr, S |
| Source | Journal of Geophysical Research, Solid Earth vol. 123, 2, 2018 p. 1072-1088, https://doi.org/10.1002/2017JB014924  Accès ouvert |
| Année | 2018 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20182000 |
| Éditeur | Wiley-Blackwell |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1002/2017JB014924 |
| Media | papier; en ligne; numérique |
| Formats | pdf |
| Programme | Géoscience pour la sécurité publique |
| Diffusé | 2018 02 23 |
| Résumé | (disponible en anglais seulement)
One primary objective of Integrated Ocean Drilling Program Expedition 365, conducted as part of the Nankai Trough Seismogenic Zone Experiment, was to recover a
temporary observatory emplaced to monitor formation pore fluid pressure and temperature within a splay fault in the Nankai subduction zone offshore SW Honshu, Japan. Here we use a 5.3Êyear time series of formation pore fluid pressure, and in
particular the response to ocean tidal loading, to evaluate changes in pore pressure and formation and fluid elastic properties induced by earthquakes. Our analysis reveals 31 earthquake-induced perturbations. These are dominantly characterized by
small transient increases in pressure (28 events) and decreases in ocean tidal loading efficiency (14 events) that reflect changes to formation or fluid compressibility. The observed perturbations follow a magnitude-distance threshold similar to that
reported for earthquake-driven hydrological effects in other settings. To explore the mechanisms that cause these changes, we evaluate the expected static and dynamic strains from each earthquake. The expected static strains are too small to explain
the observed pressure changes. In contrast, estimated dynamic strains correlate with the magnitude of changes in both pressure and loading efficiency. We propose potential mechanism for the changes and subsequent recovery, which is exsolution of
dissolved gas in interstitial fluids in response to shaking. |
| GEOSCAN ID | 310540 |
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