DOI: http://dx.doi.org/10.5027/andgeo%25x

Characterization of seismogenetic crustal faults in the southern coast of Guayaquil Gulf, Ecuador

Kervin Chunga, Maurizio Mulas, Davide Besenzon, Kenny Fernando Escobar Segovia, Jhon Galarza

Abstract


Moderate to strong earthquakes associated with active tectonic of capable crustal faults are few documented for the Ecuador’s southern coastal region. The short seismic record begins with the Guayaquil earthquake on June 11, 1787 (Mw 6.5), other destructive earthquakes are recorded on January 30, 1943 (Mw 6.2) and August 18, 1980 (Mw 6.1). This historical earthquake records not provide sufficient information to evaluate the seismic risk for faulting capable to generate earthquakes with magnitude M≥6. Earthquakes of minor magnitude are not considered in this study due to unlikely to cause ground coseismic effects. A catalog of geological fault has been delineated in this study with 40 segments capable and active faults on the sea floor of the Gulf of Guayaquil and inland segments of Guayas, Santa Elena and El Oro provinces. This methodological approach has allowed estimating levels of seismicity in the order of 6.2 to 7.2 degrees of magnitude and rock peak ground accelerations in the order of 0.41g 0.24g, these values ​​were obtained from empirical regression equations applied to the length of capable geological faults. The F-40 seismogenic structure located in the accretionary prism (near the subduction zone) is capable of generating earthquake in the order of 8.2 magnitude, and can cause ground coseismic damage to the city of Guayaquil which is located to 177 km away, furthermore local tsunami can dangerous to densely populated areas and developing industries sectors on the coast of the Gulf of Guayaquil. All this structural geological analysis provides new data to consider in studies of seismic hazard, particularly for generating control spectra  for vertical and horizontal component from capable fault close to the city of Guayaquil, the Ecuador's most populous country.


Keywords


Capable fault, crustal earthquake, estimated magnitudes, Guayaquil Gulf.

How to cite this article Chunga, K., Mulas, M., Besenzon, D., Escobar Segovia, K., and Galarza, J., 2017, Characterization of seismogenetic crustal faults in the southern coast of Guayaquil Gulf, Ecuador: Andean Geology, v. 44, no. 3, , doi:http://dx.doi.org/10.5027/andgeo%x