Earthquake Ground Effects and Intensity of the 16 April 2016 Mw 7.8 Pedernales, Ecuador, Earthquake: Implications for the Source Characterization of Large Subduction Earthquakes

Chunga, Kervin; Livio, Franz; Mulas, Maurizio; Ochoa-Cornejo, Felipe; Besenzon, Davide; Ferrario, Maria Francesca; Michetti, Alessandro Maria

doi:10.1785/0120180051

Cited by 31 publications

(36 citation statements)

References 64 publications

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“…Annual rainfall for the dry climate zone in southernmost Manabí region is less than 500 mm, measured between January and April, while the summer is very dry and hot. Annual rainfall ranges from 500 to 1000 mm for the tropical Savanna earthquake-triggered landslides accompanying the 2016 Pedernales earthquake, dots mark the types of coseismic landslides and blue lines mark the ESI-07 isoseismals as defined by [22]; the location of the photographic documentation in Figures 3 and 4 is also reported.…”

Section: Description Of the Study Areamentioning

confidence: 99%

“…Historically, the 1942 Jama (Mw 7.9) and the 2016 Pedernales (Mw 7.8) earthquakes are the largest subduction earthquakes recorded in the central segment of the subduction interface zone (Figure 2a; [48,49]). This tectonic segment registered several megathrust earthquakes, including: i) the May 3, 1896, Mw 7.1; ii) the 1 June 1907, Mw 7.4; iii) the 16 January 1956, Mw 7.4 and iv) the Mw 7.1 on August 4, 1998 earthquakes ( Figure 2, [22,50]).…”

Section: Seismotectonic Setting and The 2016 Pedernales Earthquake Sementioning

confidence: 99%

“…The earthquake sequence started with a foreshock (ML 5.7, at 18:47), some 10 minutes prior the Mw 7.8 mainshock, that occurred at 18:59 on the April 16, 2016 [20], see Data and Resources; Figure 2a). The extent of physical and environmental damage encompassed an area of thousands of square kilometers [21,22]. Locally, building damage and geological ground effects were enhanced by site amplification due to class E and F water saturated soils [23].…”

Section: Introductionmentioning

confidence: 99%

“…Coseismic geological effects were observed also across communities near Cojimíes (north of the epicenter, Figure 2b) and near Portoviejo (south of the epicenter, Figure 2b), resulting in a VIIIESI-07 assessment. The area encompassed by isoseismals VII-IX ESI07 corresponds to the deformed The epicentral area includes the city of Pedernales and surrounding communities (i.e., Coaque, Jama and Canoa), reaching a maximum intensity of IX ESI-07 , assessed from field observation of coastal uplift, soil liquefaction, sinkholes, landslides of natural and stabilized slopes, cracks in natural soils, minor fractures, failure along both the major and minor axis in pavement, particularly asphalt and concrete roads [22]. Coseismic geological effects were observed also across communities near Cojimíes (north of the epicenter, Figure 2b) and near Portoviejo (south of the epicenter, Figure 2b), resulting in a VIII ESI-07 assessment.…”

Section: Introductionmentioning

confidence: 99%

“…We present the outcome of this study together with landslide hazard maps, describing the characteristics of the surveyed landslides and providing new insights into the controlling factors of coseismic landslides during large subduction earthquakes. Pedernales earthquake, dots mark the types of coseismic landslides and blue lines mark the ESI-07 isoseismals as defined by [22]; the location of the photographic documentation in Figures 3 and 4 is also reported.…”

Section: Introductionmentioning

confidence: 99%

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Landslides Triggered by the 2016 Mw 7.8 Pedernales, Ecuador Earthquake: Correlations with ESI-07 Intensity, Lithology, Slope and PGA-h

et al. 2019

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We provide a dataset of the landslides induced by the 2016 Pedernales megathrust earthquake, Ecuador (Mw 7.8, focal depth of 20 km) and compare their spatial distribution with mapped bedrock lithology, horizontal peak ground acceleration (PGA-h) and the macroseismic intensity based on earthquake-induced environmental effects (ESI-07). We studied 192 coseismic landslides (classified as coherent, disrupted and lateral spreads) located in the epicentral area, defined by the VII to IXESI-07 isoseismals. Based on our findings, lahar deposits, tuffs and volcanoclastic units are the most susceptible to landslides occurrence. Alluvial plains with fluvial loose fine sand are the most susceptible setting for lateral spreading, with a maximum intensity of IXESI-07. The coherent landslides are frequently found in altered shale and siltstone geological units with moderate slopes (8°–16°), with typical intensity ranging between VII and VIIIESI-07. Our analysis draws a typical framework for slope movements triggered by subduction earthquakes in Ecuador. The most dangerous setting is the coastal region, a relatively highly urbanized area located near the epicenter and where liquefaction can trigger massive lateral spreading events. Coherent and disrupted landslides, dominating the more internal hilly region, can be triggered also in moderate slope settings (i.e., less than 10°). Indeed, the regression analysis between seismic intensity, PGA-h and landslide occurrence shows that most of the events occurred at PGA-h values between 0.4 g and 1.2 g, at a distance of 30 to 50 km from the rupture plane. Our database suggests that lithology and hillslope geometry are the main geological/geomorphological factors controlling coseismic landslides occurrence; while the distance from the rupture plane plays a significant role on determining the landslide size. Finally, we underline that coseismically-triggered landslides are among the most common environmental effects occurring during large subduction events that can be effectively used to properly evaluate the earthquake macroseismic field. The landslide inventory we compiled is suitable for assessing the vulnerability of physical environment from subduction earthquakes in Ecuador, and offers a primary data source for future worldwide analysis.

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Section: Description Of the Study Areamentioning

confidence: 99%