Geological lineaments are linear or curvilinear surfaces that are considered a superficial expression of discontinuities on the earth’s surface. The extraction of lineaments from remotely sensed satellite data is one of the most frequently used applications of remote sensing in geology. This study focuses on the semi-automatic extraction of lineaments in the Girón–Santa Isabel basin using a Topographic Position Index (TPI). The lineaments were extracted in the PCI Geomatics 2016 software and analyzed in the ArcGIS and Rockworks software. Statistical and density map analyses of the lineaments were performed; then, these results were interpreted to obtain the geological lineaments. Finally, a bibliographic verification was carried out, and structures such as faults and folds were defined. The total number of geological lineaments was 76, and 71 of them were defined as faults, the longest with a length of 33 km. It was determined that the preferential orientation of the lineaments is NE–SW, which is consistent with the axis of the Girón–Santa Isabel basin. This methodology can be useful to optimize time and reduce costs when gathering the structural information of the study area in the first stage of geological and mining prospecting or the educational field.

Starting on the day after the mainshock, we mapped in the field and compiled all the available observations on earthquake environmental effects (EEEs) caused by the $Mw$ 7.8 subduction earthquake that hit the coastal region of Ecuador on 16 April 2016 (the Pedernales earthquake). These effects include: (a) permanent ground deformation, (b) open cracks, (c) liquefaction, (d) landslides, and (e) tsunami waves. We use these observations to evaluate the macroseismic field of the Environmental Seismic Intensity (ESI‐07) scale and compare our results with published macroseismic data collected using traditional damage‐based intensity scales. We found systematic difference in the assessed earthquake intensity and in the intensity attenuation with distance. A comparison of our dataset with the macroseismic data of six instrumental large‐subduction earthquakes that occurred between Ecuador and Chile suggests that, for the Pedernales earthquake, the ESI‐07 works better in the near field, whereas damage‐based scales are more reliable in the far field. Therefore, we generate a single integrated intensity dataset for the Pedernales earthquake, including data measured with the European Macroseismic Scale 1998 (EMS‐98), the modified Mercalli (MM) scale, and the ESI‐07 scale. This new integrated macroseismic field provides reliable and comparable information on the seismogenic source, suggesting that a similar approach could be successfully applied to refine the source model of past subduction earthquakes in Ecuador and elsewhere.

Few moderate-to-strong earthquakes associated with active and capable geological faults have been documented for the southern coastal region of Ecuador. The seismic record of Ecuador initiates with the Guayaquil earthquake in 1787 (Mw 6.5), followed by the 1943 (Mw 6.2), and the most recent one in 1980 (Mw 6.1). The available data is insufficient to evaluate the seismic hazards associated with faults capable of generating seismic events of magnitude Mw≥6.0 in the region. Also, earthquakes of minor magnitudes can be disregarded as they do not induce significant ground coseismic effects. In this context, this study presents a catalog of geological faults, delineating 40 segments of 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 estimates a variety of seismicity levels ranging between Mw 6.2 and Mw 7.2, with rock peak ground accelerations between 0.24 g and 0.41 g. These values have been obtained from empirical regression equations applied to the length of capable geological faults. The F-40 seismogenic structure located in the accretionary prism, close to the subduction zone, is capable of generating Mw 8.2 earthquakes and potentially causing coseismic ground damage to the city of Guayaquil located ca. 177 km to the NE. Furthermore, local tsunami hazards may affect severely areas that are densely populated, with developing industrial areas, on the coast of the Gulf of Guayaquil. This structural geological analysis provides useful new data for seismic hazard assessment.