Proceedings of the 12th International INQUA meeting on paleoseismology, active tectonic and archaeoseismology

288 1 2 T H I N T E R N AT I O N A L I N Q U A M E E T I N G O N PA L E O S E I S M O L O G Y , A C T I V E T E C T O N I C S A N D A R C H A E O S E I S M O L O G Y ( PATA ) , O C T O B E R 6 T H - 1 1 T H , 2 0 2 4 , L O S A N D E S , C H I L E PATA Days 2024 K E Y W O R D S Porotoyacu Fault, Paleoseismology, outcrop, seismites, magnitude (1) Universidad Regional Amazónica Ikiam, Parroquia Muyuna, Kilometer 7 via Alto Tena, s/n, Tena, Napo, Ecuador. Email: (2) Earth Sciences and Climate Research Group. Universidad Regional Amazónica Ikiam, Tena, Ecuador (3) Universidad Técnica de Manabí. Maestría en Prevención y Gestión de Riesgos de la Facultad de posgrado de la Universidad Técnica de Manabí. Portoviejo, Ecuador. *Email: samira.lluno@est.ikiam.edu.ec Samira Lluno (1) Henry Conteron (1) Oswaldo Guzmán (2) Corina Campos (2) Carolina Cornejo (3) PALEOSEISMOLOGICAL STUDY OF THE POROTOYACU FAULT IN THE AMAZON ECUADORIAN PIEDMONT A B S T R A C T The tectonics activity intheAmazonhasnotbeenstudied indepth. An example of this is the Porotoyacu Fault through populations in the Amazon region. A paleoseismological study is being carried out in the south of the city of Tena. To decipher the paleoseismicity engraved in outcrop i.e. calculate the number and magnitude of seismic events and identify the structure of deformation or seismites. On the outcrop have recognized two paleo-ruptures. The first with normal kinematics with two events with magnitudes between Mw~6.7 and 6.8 and surface wave magnitude of Ms=6.9. The second is reverse with an only event of magnitude 613<Mw<6.52 and Ms=6.24. In addition, between the structure of deformation identify their load cast, flame structures, dikes, and pseudonodules originating from earthquake M>5. Finally, these deformation structures in the overlying units indicate direct geologic evidence of Quaternary seismic activity of the Porotoyacu fault. I N T R O D U C T I O N Ecuador is in a tectonic active regimen by the convergent of the Nazca plate and Sudamericana plate. Resulting in 92 Quaternary faults identified as superficial with aerial photographs in the map of the quaternary fault of Ecuador (Eguez, et al., 2003). Despite this, earthquakes are generally of magnitude 4.5 or lower at the Ecuador (IG-EPN, 2024). But existing registrations of atypical events with > 6 located in Napo province (Council, 1991) implying that high seismic events may occur in the Amazonia. Another example is the study by (Baby, Rivadeneira, & Barragán, 2004) in 1995 that registered an earthquake = 7.0 correlated to the system of faults Cutucú-Napo.