Numerous sand boils were generated in the alluvial plain at the mouth of the Rio Brice˜no valley (Ecuador) during the Mw 7.8 earthquake of April 2016. The area is characterized by a series of raised marine terraces formed as a consequence of the rapid tectonic coastal uplift during the Quaternary. Boreholes and geotechnical investigations were carried during post-earthquake surveys and for the purpose of mitigating the liquefaction effects. Five lithological units were identified at a site of embankment, which represented continental-marine and transitional sedimentation since the Last Glacial Maximum. A comprehensive study of texture and petrographic composition of sand boils has been performed and compared with sandy silts and silty sands of the buried sedimentary sequence in order to identify the source levels for liquefaction. The petrographic components, in particular the low content of bioclasts and carbonate fragments of the sand boils, allow to pinpoint a source layer made up of fine-grained silty sands located between 2 and 4.5 m depth (Unit 2) whereas the deeper marine sands, richer in bioclasts, were not involved. The results support the idea that earthquake-induced liquefaction phenomena are not restricted to clean sands and well-sorted deposits, but may affect sand layers with significant amount of nonplastic silt.

Liquefaction source layer for sand blows induced by the 2016 megathrust earthquake (Mw 7.8) in Ecuador (Boca de Briceño) / Salocchi, Aura C.; Minarelli, Luca; Lugli, Stefano; Amoroso, Sara; Rollins, Kyle M.; Fontana, Daniela. - In: JOURNAL OF SOUTH AMERICAN EARTH SCIENCES. - ISSN 0895-9811. - 103:(2020), pp. 1-10. [10.1016/j.jsames.2020.102737]

Liquefaction source layer for sand blows induced by the 2016 megathrust earthquake (Mw 7.8) in Ecuador (Boca de Briceño)

Salocchi, Aura C.;Lugli, Stefano
Writing – Review & Editing
;
Fontana, Daniela
Writing – Original Draft Preparation
2020

Abstract

Numerous sand boils were generated in the alluvial plain at the mouth of the Rio Brice˜no valley (Ecuador) during the Mw 7.8 earthquake of April 2016. The area is characterized by a series of raised marine terraces formed as a consequence of the rapid tectonic coastal uplift during the Quaternary. Boreholes and geotechnical investigations were carried during post-earthquake surveys and for the purpose of mitigating the liquefaction effects. Five lithological units were identified at a site of embankment, which represented continental-marine and transitional sedimentation since the Last Glacial Maximum. A comprehensive study of texture and petrographic composition of sand boils has been performed and compared with sandy silts and silty sands of the buried sedimentary sequence in order to identify the source levels for liquefaction. The petrographic components, in particular the low content of bioclasts and carbonate fragments of the sand boils, allow to pinpoint a source layer made up of fine-grained silty sands located between 2 and 4.5 m depth (Unit 2) whereas the deeper marine sands, richer in bioclasts, were not involved. The results support the idea that earthquake-induced liquefaction phenomena are not restricted to clean sands and well-sorted deposits, but may affect sand layers with significant amount of nonplastic silt.
2020
103
1
10
Liquefaction source layer for sand blows induced by the 2016 megathrust earthquake (Mw 7.8) in Ecuador (Boca de Briceño) / Salocchi, Aura C.; Minarelli, Luca; Lugli, Stefano; Amoroso, Sara; Rollins, Kyle M.; Fontana, Daniela. - In: JOURNAL OF SOUTH AMERICAN EARTH SCIENCES. - ISSN 0895-9811. - 103:(2020), pp. 1-10. [10.1016/j.jsames.2020.102737]
Salocchi, Aura C.; Minarelli, Luca; Lugli, Stefano; Amoroso, Sara; Rollins, Kyle M.; Fontana, Daniela
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11380/1207910
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