Geotechnical aspects of the 2015 Mw 8.3 illapel megathrust earthquake sequence in Chile

Gabriel Candia, Gregory P. De Pascale, Gonzalo Montalva, Christian Ledezma

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


The 2015 Illapel earthquake sequence in Central Chile, occurred along the subduction zone interface in a known seismic gap, with moment magnitudes of Mw 8.3, Mw 7.1, and Mw 7.6. The main event triggered tsunami waves that damaged structures along the coast, while the surface ground motion induced localized liquefaction, settlement of bridge abutments, rockfall, debris flow, and collapse in several adobe structures. Because of the strict seismic codes in Chile, damage to modern engineered infrastructure was limited, although there was widespread tsunami-induced damage to one-story and two-stories residential homes adjacent to the shoreline. Soon after the earthquake, shear wave measurements were performed at selected potentially liquefiable sites to test recent VS-based liquefaction susceptibility approaches. This paper describes the effects that this earthquake sequence and tsunami had on a number of retaining structures, bridge abutments, and cuts along Chile's main highway (Route 5). Since tsunami waves redistribute coastal and near shore sand along the coast, liquefaction evidence in coastal zones with tsunami waves is sometimes obscured within minutes because the tsunami waves entrain and deposit sand that covers or erodes evidence of liquefaction (e.g., lateral spread or sand blows). This suggests that liquefaction occurrence and hazard may be under estimated in coastal zones. Importantly, the areas that experienced the greatest coseismic slip, appeared to have the largest volumes of rockfall that impacted roads, which suggests that coseismic slip maps, generated immediately after the shaking stops, can provide a first order indication about where to expect damage during future major events.

Original languageEnglish
Pages (from-to)709-728
Number of pages20
JournalEarthquake Spectra
Issue number2
Publication statusPublished - May 2017

Bibliographical note

Funding Information:
The authors greatly appreciate the support of the Geotechnical Extreme Events Reconnaissance (GEER) Steering Committee, in particular Prof. Jonathan Bray for supporting this research. Funding for this work was provided by the National Research Center for Integrated Natural Disaster Management CONICYT/FONDAP/ 15110017; Candia was also sponsored by Universidad del Desarrollo. De Pascale and the Universidad de Chile group were supported by a FCFM (UChile) academic fund and CEGA FONDAP CONICYT 15090013. Montalva and the Universidad de Concepción group were funded by FONDECYT 1140317 and Water Research Center for Agriculture and Mining CONICYT/FONDAP/15130015. Ledezma was funded by FONDECYT 11110125 and by CONICYT USA2012-0007. Thanks to Prof. Gabriel Vargas for providing some Tsunami observations. Thanks to Prof. Esteban Sáez and his team for performing the shear wave velocity measurements. Participation of GEER Steering Committee personnel in coordinating and reviewing the report was made possible by the U.S. National Science Foundation (NSF) through Grant No. CMMI-1266418. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the NSF.

Publisher Copyright:
© 2017, Earthquake Engineering Research Institute.


Dive into the research topics of 'Geotechnical aspects of the 2015 Mw 8.3 illapel megathrust earthquake sequence in Chile'. Together they form a unique fingerprint.

Cite this