Publication Date:
2023-06-19
Description:
The San Rafael waterfall sinkhole on the Coca River in February 2020 caused by soil erosion raises the question of the stability of the knickpoint structure. The main objective of this research is to obtain tomographic images to interpret the seismic stratigraphic profile around the San Rafael knickpoint using seismic tomography. We use data from fourteen seismic stations of the permanent Ecuadorian seismic network in the region. The tomography results for the vertical cross-section P-wave velocity model show the geological formations and their transition to volcanic deposits. It also shows a structure with a high P-wave velocity value directly below the knickpoint. In contrast, the horizontal cross-section shows the structure of the extension of the volcanic deposits. The relative P-wave velocity shows a volumetric structure below the last pyroclastic deposits generated by the Reventador. The dimensions and characteristic velocity of the anomaly allow us to relate it to an igneous intrusion similar to the granodioritic intrusions known to the east of the volcano cone. Therefore, the presence of this pluton should condition the stability of the Coca riverbed, its slopes, and cliffs. The volcanic deposits in direct contact with the intrusion are suspected to be poorly consolidated. The P-wave velocity model shows that these volcanic deposits have an extension of 40 km. Greater stability is expected upstream of the San Rafael pluton. The relocation obtained by tomography also allows for defining the possible magmatic feeding system of the Reventador volcano.
Language:
English
Type:
info:eu-repo/semantics/conferenceObject
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