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NAO

North Andean Subduction International Observatory

- P. Charvis -

Mitigating earthquake hazard requests transdisciplinary research from physical process analysis to social, environmental and development impacts’ studies

Deployment of an up-to-date ocean bottom seismometer (built in Géoazur) to record offshore earthquakes and measure telluric deformation Deployment of an up-to-date ocean bottom seismometer (built in Géoazur) to record offshore earthquakes and measure telluric deformation

Academy 3 highlight

The study, understanding and prevention of large earthquakes require a transdisciplinary approach involving scientists with various expertise (geology, seismology, physics, engineering, social sciences). NAO gathers these scientists and establishes new foundations for their cooperation on large earthquake studies.

The project

The NAO project focuses on the Andean subduction zone in South America where one tectonic Plate (Nazca Plate) that forms the floor of the Pacific Ocean slides and sinks below the continental South-American Plate. The sliding of the two plates generates frequent (every few decades) very large earthquakes (with magnitudes generally greater than 8), making the Andean subduction zone one of the regions in the world with the highest seismic hazard. This region is also densely populated and hosts huge cities along the coast, which are thus highly vulnerable to natural hazards, especially since they are part of developing countries. It is our responsibility to help the threatened western South American countries to build safe and resilient societies. This can furthermore teach us how to build safer cities in our regions where natural hazards, though generally lower, do exist.

The NAO project has led several initiatives to monitor and assess seismic hazard and vulnerability in the northern part of the Andean subduction zone. These initiatives have been co-funded by the ANR, IRD and the CNRS. As an example, immediately after the large Pedernales earthquake (magnitude 7.8) which struck Ecuador in April 2016, we deployed, as part of an international collaboration, an array of ~80 onshore-offshore sensors (seismometers and GPS) to monitor the ongoing seismic activity and the immediate deformations following the main shock. The data analysis revealed that the post-earthquake deformations are mainly controlled by the topography of the sinking plate (Agurto-Detzel et al., 2019). We are now testing an innovative in situ seabed instrument system (see figure) off the coast of Nice to observe and measure with higher resolution the accumulating telluric deformations. Once the tests are successful, we will deploy these instruments in the Andean subduction zone.

3D sketch of the subduction of the Nazca Plate beneath the South American Plate 3D sketch of the subduction of the Nazca Plate beneath the South American Plate

The +

Within the frame of this project, UCA researchers had the opportunity to attend an international workshop that was held in September 2017. Several prominent scientists contributed, addressing a wide variety of topics including flood risk management, climate change adaptation, local disaster risk reduction, and transdisciplinary relations between different groups of people involved in disaster prevention and response phases.

What’s next?

Funding of this project by Academy 3 has already enabled the leveraging of additional funding from the ANR, IRD and CNRS. In future years, we will expand our activities by leading a marine geophysics campaign to image with seismic instruments the rupture zone of the 2016 Pedernales earthquake in Ecuador. We will coordinate an international network to study the Andean subduction zone and associated hazards. We will also organize a summer school entitled « Risks and knowledge » in July 2020 aimed at scientists and PhDs from France and developing countries.

Project information

Scientific domain Earth sciences Theme Seismology	Key words Earthquake Seismic Risk Transdisciplinary
Total budget 30 k€ (A3 for the NAO project), 49 k€ (co-funded by A2 and A3 for a one year postdoc position : Hans Agurto-Detzel), 290 k€ (ANR REMAKE), 150 k€ (rapid response deployment after the 2016 earthquake in Ecuador, supported by IRD and CNRS-INSU).	Students inolved Caroline Chalumeau (Géoazur) (PhD) Paul JARRIN (Géoazur) (PhD) Daniel PACHECO (Géoazur) (PhD)
Partner laboratories ESPACE GREDEG SKEMA CEREMA (Centre d’études et d’expertise sur les risques, l’environnement, la mobilité et l’aménagement) International collaborations Instituto Geofísico de la Escuela Politécnica Nacional (Quito Ecuador) Escuela Superior Politécnica del Litoral (Guayaquil Ecuador) Distrito Metropolitano de Quito (Ecuador) Instituto Geofísico del Perú (Lima Perú) Universidad de Chile (Santiago Chile)	Project members Audrey Galve Diego Mercerat Diego Moreno Groslambert Bertrand Hans Agurto-Detzel Philippe Charvis Quentin Bletery Steichen Pascale

Philippe Charvis

GEOAZUR, Université Côte d’Azur

Project valorization

Publications:

Agurto-Detzel, H., Font, Y., Charvis, P., Rietbrock, A., Ambrois, D., Paulatto, M., Alvarado, A., Beck, S., Hernandez, M.J., Hoskins, M., León-Ríos, S., Lynner, C., Meltzer, A., Michaud, F., Nocquet, J.-M., Régnier, M., Rolandone, F., Ruiz, M., Soto-Cordero, L., 2019. Ridge subduction and afterslip control aftershock distribution of the 2016 Mw 7.8 Ecuador earthquake. Earth Planet. Sci. Lett. 520, 63–76. doi:10.1016/j.epsl.2019.05.029
Ioualalen, M., Pazmiño, A. N., Renteria, W. J., Charvis, P., Gordillo, G. X. S., Delouis, B., Nath, J., Gomez, H., Aguilar, J. G. C., & Gallegos, L. A. B. (2018). Analysis of Tsunami Tide Gauge Records Following the 2016 Ecuadorian Earthquake and Tsunami. J. Waterway, Port, Coastal, Ocean Eng., 144(2), 1–8. https://doi.org/10.1061/(ASCE)WW.1943-5460.0000431.
Koch, C. D., Lynner, C., Delph, J., Beck, S. L., Meltzer, A., Font, Y., Soto-Cordero, L., Hoskins, M., Stachnik, J. C., Ruiz, M., Alvarado, A., Agurto-Detzel, H., Charvis, P., Regnier, M., & Rietbrock, A. (2020). Structure of the Ecuadorian forearc from the joint inversion of receiver functions and ambient noise surface waves. GEOPHYSICAL JOURNAL INTERNATIONAL, 222(3), 1671–1685. https://doi.org/10.1093/gji/ggaa237
Leon-Rios, S., Agurto-Detzel, H., Rietbrock, A., Alvarado, A., Beck, S., Charvis, P., Edward, B., Font, Y., Garth, T., Hoskins, M., Lynner, C., Meltzer, A., Nocquet, J. M., Regnier, M., Rolandone, F., Ruiz, M., & Soto-Cordero, L. (2019). 1D-velocity structure and seismotectonics of the Ecuadorian margin inferred from the 2016 Mw7.8 Pedernales aftershock sequence. TECTONOPHYSICS, 767. https://doi.org/10.1016/j.tecto.2019.228165
Lynner, C., Koch, C., Beck, S. L., Meltzer, A., Soto-Cordero, L., Hoskins, M. C., Stachnik, J. C., Ruiz, M., Alvarado, A., Charvis, P., Font, Y., Regnier, M., Agurto-Detzel, H., Rietbrock, A., & Porritt, R. W. (2020). Upper-plate structure in Ecuador coincident with the subduction of the Carnegie Ridge and the southern extent of large mega-thrust earthquakes. GEOPHYSICAL JOURNAL INTERNATIONAL, 220(3), 1965–1977. https://doi.org/10.1093/gji/ggz558
Meltzer, A., Beck, S. L., Ruiz, M., Soto-cordero, L., Stachnik, J. C., Lynner, C., Porritt, R., Portner, D., Alvarado, A., Hernandez, S., Yepes, H., Charvis, P., Font, Y., Reigner, M., Agurto-detzel, H., Rietbrock, A., Leon-rios, S., & Mercerat, E. D. (2019). The 2016 Mw 7.8 Pedernales, Ecuador, Earthquake: Rapid Response Deployment by. Seismological Research Letters, 90(3). https://doi.org/10.1785/0220180364
Pigeon, P., & Rebotier, J. (2019). Que nous apprennent les bases de données sur les désastres associés aux séismes ? Réflexions géographique et géohistorique sur la ville d’Esmeraldas (Équateur). Physio-Géo, Volume 14, 113–146. https://doi.org/10.4000/physio-geo.9036
Rebotier J., Pigeon P. (2017) Workshop Interdisciplinarity / Transdisciplinarity in Disaster Risk Assessment. Synthetic Report ANR-REMAKE Research Project (Seismic Risk in Ecuador: Mitigation, Anticipation and Knowledge of Earthquakes), 9 p. => https://halshs.archives-ouvertes.fr/halshs-01621659/document
Rebotier, J., Pigeon, P., & Metzger, P. (2019). Returning social context to seismic risk knowledge & management. Lessons learned from an interdisciplinary research in the city of Esmeraldas, Ecuador. Cybergeo. https://doi.org/10.4000/cybergeo.31787
Soto-Cordero, L., Meltzer, A., Bergman, E. A., Hoskins, M., Stachnik, J. C., Agurto-Detzel, H., Alvarado, A., Beck, S. L., Charvis, P., Font, Y., Hayes, G. P., Hernandez, S., Leon-Rios, S., Lynner, C., Nocquet, J.-M., Regnier, M., Rietbrock, A., Rolandone, F., & Ruiz, M. (2020). Structural Control on Megathrust Rupture and Slip Behavior: Insights From the 2016 Mw 7.8 Pedernales Ecuador Earthquake. JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 125(2). https://doi.org/10.1029/2019JB018001

Conferences:

Agurto-Detzel, H., Font, Y., Charvis, P., Alvarado, A. P., Ambrois, D., Beck, S. L., Hoskins, M., Leon Rios, S., Lynner, C., & Meltzer, A. (2018). Aftershocks of the 2016 Mw 7.8 Ecuador Earthquake Reveal Earthquake Cycle is Controlled by Long-Lived Structures. AGU Fall Meeting, 2018, T52B-04.
Agurto-Detzel, H., Rivet, D., & Charvis, P. (2020). Seismic velocity changes in the epicentral area of the Mw 7.8 Pedernales (Ecuador) earthquake from cross-correlation of ambient seismic noise. EGU General Assembly Conference Abstracts, 17543.
Chalumeau, C., Agurto-Detzel, H., De Barros, L., Charvis, P., Font, Y., Rietbrock, A., Galve, A., Alvarado, A. P., Beck, S. L., & Hernandez, S. (2019). Repeating Aftershocks of the 16 th April 2016 Mw 7.8 Pedernales (Ecuador) Earthquake Underline the Interplay Between Afterslip and Seismicity. AGU Fall Meeting, 2019, T53C-06.
Font, Y., Agurto-Detzel, H., Alvarado, A. P., Regnier, M. M., Rolandone, F., Charvis, P., Mothes, P. A., Nocquet, J. M., Jarrin, P., & Ambrois, D. (2017). Aftershock Distribution of the M w= 7.8 April 16, 2016 Pedernales Ecuador Subduction Earthquake: Constraints from 3D Earthquake Locations. AGU Fall Meeting, 2017, S51G-06.
Galve, A., Charvis, P., Regnier, M. M., Font, Y., Nocquet, J. M., & Segovia, M. (2017). Imaging the deep structures of the convergent plates along the Ecuadorian subduction zone through receiver function analysis. AGU Fall Meeting, 2017, S53C-0711.
Hello, Y., Yegikyan, M., Charvis, P., & Philippe, O. (2017). Manta A New BroadBand OBS. AGU Fall Meeting, 2017, S11C-0604.
Hoskins, M. C., Meltzer, A., Stachnik, J., Agurto-Detzel, H., Alvarado, A. P., Beck, S. L., Charvis, P., Font, Y., Hernandez, S., & Koch, C. D. (2019). Structural Controls on Postseismic Deformation Following the M w 7.8 Pedernales, Ecuador Megathrust Earthquake: Insights from Joint Tomographic Inversion and Aftershock Relocation. AGU Fall Meeting, 2019, T31G-0352.
Hoskins, M., Meltzer, A., Soto-Cordero, L., Stachnik, J., Beck, S. L., Lynner, C., Ruiz, M. C., Alvarado, A. P., Hernandez, S., & Charvis, P. (2018). Variable slip modes in postseismic deformation north of the April 16, 2016 M w 7.8 Pedernales, Ecuador megathrust earthquake. AGU Fall Meeting, 2018, T43E-0444.
Koch, C. D., Lynner, C., Delph, J. R., Beck, S. L., Meltzer, A., Hoskins, M., Soto-Cordero, L., Ruiz, M. C., Alvarado, A. P., & Font, Y. (2018). Crustal Structure of the Ecuadorian Forearc from the Joint Inversion of Receiver Functions and Ambient Noise Dispersion Data. AGU Fall Meeting, 2018, T43E-0459.
Laigle, M., Agurto-Detzel, H., Bécel, A., Boucard, M., Chalumeau, C., Charvis, P., Dessa, J.-X., Galve, A., Hernandez, M.-J., & Hussni, S. (2020). Imaging the megathrust in subduction zones: lessons from Greece, Ecuador and the Lesser Antilles. EGU General Assembly Conference Abstracts, 14636.
Leon-Rios, S., Aguiar, A. L., Bie, L., Edwards, B., Fuenzalida Velasco, A. J., Holt, J., Garth, T., González, P. J., Rietbrock, A., & Agurto-Detzel, H. (2017). The 2016 Mw 7.8 Pedernales, Ecuador earthquake: Minimum 1D Velocity Model and Regional Moment Tensors Based on the Aftershock Sequence. AGU Fall Meeting, 2017, S53C-0717.
Leon-Rios, S., Agurto-Detzel, H., Rietbrock, A., Alvarado, A. P., Beck, S. L., Charvis, P., Edwards, B., Font, Y., Garth, T., & Galve, A. (2019). 3D seismic tomography in the rupture area of the 2016 Mw 7.8 Pedernales, Ecuador, earthquake: Imaging seismic properties along the subduction zone interface. AGU Fall Meeting, 2019, T41C-06.
Lynner, C., Beck, S. L., Koch, C. D., Metlzer, A., Soto-Cordero, L., Ruiz, M. C., Alvarado, A. P., Charvis, P., Font, Y., & Regnier, M. M. (2018). Ambient noise tomography across Ecuador: Upper-plate structure coincident with the Carnegie Ridge and the southernmost extent of mega-thrust earthquakes. AGU Fall Meeting, 2018, T21F-0278.
Lynner, C., Beck, S. L., Porritt, R., Meltzer, A., Alvarado, A. P., Gabriela, P., Ruiz, M. C., Hoskins, M., Stachnik, J., & Rietbrock, A. (2017). Ambient noise tomography of Ecuador: Fore-and back-arc velocity structure and radial anisotropy. AGU Fall Meeting, 2017, T32B-05.
Regnier, M. M., Segovia, M., Font, Y., Charvis, P., Galve, A., Jarrin, P., Hello, Y., Ruiz, M. C., & Pazmino, A. (2017). Seismicity near a Highly-Coupled Patch in the Central Ecuador Subduction Zone. AGU Fall Meeting, 2017, S53C-0710.
Sallares, V., Melendez, A., Terzic, D., Buinheira, P., Charvis, P., Galve, A., Collot, J.-Y., & Calahorrano B, A. (2020). 3D distribution of elastic properties and subduction inter-plate relief in NW Ecuador from joint refraction and inter-plate reflection travel-time tomography. EGU General Assembly Conference Abstracts, 5842.
Soto-Cordero, L., Nealy, J. L., Meltzer, A., Agurto-Detzel, H., Alvarado, A. P., Beck, S. L., Benz, H., Bergman, E. A., Charvis, P., & Font, Y. (2017). New insights on co-and post-seismic deformation and slip behavior associated with the Mw7. 8 2016 Pedernales, Ecuador earthquake and its aftershock sequence. AGU Fall Meeting, 2017, S53C-0715.