TY  - JOUR
A1  - Yepes, Hugo
A1  - Audin, Laurence
A1  - Alvarado, Alexandra
A1  - Beauval, Celine
A1  - Aguilar, Jorge
A1  - Font, Yvonne
A1  - Cotton, Fabrice Pierre
T1  - A new view for the geodynamics of Ecuador: Implication in seismogenic source definition and seismic hazard assessment
JF  - Tectonics
N2  - A new view of Ecuador's complex geodynamics has been developed in the course of modeling seismic source zones for probabilistic seismic hazard analysis. This study focuses on two aspects of the plates' interaction at a continental scale: (a) age-related differences in rheology between Farallon and Nazca plates—marked by the Grijalva rifted margin and its inland projection—as they subduct underneath central Ecuador, and (b) the rapidly changing convergence obliquity resulting from the convex shape of the South American northwestern continental margin. Both conditions satisfactorily explain several characteristics of the observed seismicity and of the interseismic coupling. Intermediate-depth seismicity reveals a severe flexure in the Farallon slab as it dips and contorts at depth, originating the El Puyo seismic cluster. The two slabs position and geometry below continental Ecuador also correlate with surface expressions observable in the local and regional geology and tectonics. The interseismic coupling is weak and shallow south of the Grijalva rifted margin and increases northward, with a heterogeneous pattern locally associated to the Carnegie ridge subduction. High convergence obliquity is responsible for the North Andean Block northeastward movement along localized fault systems. The Cosanga and Pallatanga fault segments of the North Andean Block-South American boundary concentrate most of the seismic moment release in continental Ecuador. Other inner block faults located along the western border of the inter-Andean Depression also show a high rate of moderate-size earthquake production. Finally, a total of 19 seismic source zones were modeled in accordance with the proposed geodynamic and neotectonic scheme.
Y1  - 2016
U6  - https://doi.org/10.1002/2015TC003941
SN  - 0278-7407
SN  - 1944-9194
VL  - 35
SP  - 1249
EP  - 1279
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Derras, Boumediene
A1  - Bard, Pierre-Yves
A1  - Cotton, Fabrice Pierre
T1  - Site-Condition Proxies, Ground Motion Variability, and Data-Driven GMPEs: Insights from the NGA-West2 and RESORCE Data Sets
JF  - Earthquake spectra : the professional journal of the Earthquake Engineering Research Institute
N2  - We compare the ability of various site-condition proxies (SCPs) to reduce the aleatory variability of ground motion prediction equations (GMPEs). Three SCPs (measured V-S30, inferred V-S30, local topographic slope) and two accelerometric databases (RESORCE and NGA-West2) are considered. An artificial neural network (ANN) approach including a random-effect procedure is used to derive GMPEs setting the relationship between peak ground acceleration (PGA), peak ground velocity (PGV), pseudo-spectral acceleration [PSA(T)], and explanatory variables (M-w, R-JB, and V-S30 or Slope). The analysis is performed using both discrete site classes and continuous proxy values. All "non-measured" SCPs exhibit a rather poor performance in reducing aleatory variability, compared to the better performance of measured V-S30. A new, fully data-driven GMPE based on the NGA-West2 is then derived, with an aleatory variability value depending on the quality of the SCP. It proves very consistent with previous GMPEs built on the same data set. Measuring V-S30 allows for benefit from an aleatory variability reduction up to 15%.
Y1  - 2016
U6  - https://doi.org/10.1193/060215EQS082M
SN  - 8755-2930
SN  - 1944-8201
VL  - 32
SP  - 2027
EP  - 2056
PB  - Earthquake Engineering Research Institute
CY  - Oakland
ER  -