9. Garcia-Delgado, H; Petley, DN; Bermudez, MA; Sepúlveda, SA.Fatal landslides in Colombia (from historical times to 2020) and their socio-economic impacts.Landslides, 2022, Fatal landslides in Colombia (from historical times to 2020) and their socio-economic impacts
Landslide; Debris flow; Socio-economic indexes; Colombia; ENSO
Landslides typify one of the most hazardous natural phenomena fostering economic and even human losses worldwide. Several countries like Colombia, in South America, are hotspots for fatal landslides. In this contribution, we thoroughly reviewed four available databases, articles, grey literature and web resources, in order to build up a new catalogue of fatal landslides in Colombia. We gathered a catalogue of 2351 individual fatal landslides which caused about 37,959 deaths. Of these, we found 11 fatal events in historical times (pre-twentieth century). In modern times (1912-2020), we analysed landslides' spatial and temporal distribution, finding that in central-western Colombia, particularly in the departments of Caldas, Risaralda, Quindio and Antioquia, these kinds of events are more frequent. Upward trends in these areas and a nationwide increase in the number of events in the last 20 years suggest that fatal landslides are far from being effectively mitigated. Our findings also show a strong correlation between the climate variability phenomenon known as El Nino Southern Oscillation (ENSO) and fatal landslides, particularly during those years when strong La Nina (cold phase of ENSO) events occur. Despite rainfall being the most common trigger for fatal landslides, we observed an increasing trend in anthropogenically related events in the last decade. Finally, we obtained multiple socio-economic indices and ran a statistical analysis at the departmental level in order to assess whether impoverished and vulnerable people are more affected by fatal landslides. We propose that in most cases, departments with low income, high levels of corruption and inequality are usually more affected. DOI
6. Brain, M.J.; Moya, S.; Kincey, M.E.; Tunstall, N.; Petley, D.N.; Sepúlveda, S.A.Controls on post-seismic landslide behaviour in brittle rocks.Journal of Geophysical Research - Earth Surface, 2021, 126, e2021JF006242 Controls on post-seismic landslide behaviour in brittle rocks
DOI
5. De Pascale, GP; Froude, M; Penna, I; Hermanns, RL; Sepúlveda, SA; Moncada, D; Persico, M; Easton, G; Villalobos, A; Gutierrez, F.Liquine-Ofqui's fast slipping intra-volcanic arc crustal faulting above the subducted Chile Ridge.Sci Rep, 2021, 11 Liquine-Ofqui's fast slipping intra-volcanic arc crustal faulting above the subducted Chile Ridge
The southernmost portion of the Liquine-Ofqui fault zone (LOFZ) lies within the proposed slab window which formed due to oblique subduction of the Chile Ridge in Patagonia. Mapping of paleo-surface ruptures, offsets, and lithological separations along the master fault allowed us to constrain geologic slip rates for the first time with dextral rates of 11.6-24.6 mm/year (Quaternary) and 3.6-18.9 mm/year (Late-Cenozoic) respectively. We had trouble mapping the LOFZ in one local because of a partially collapsed and previously undiscovered volcanic complex, Volcan Mate Grande (VMG: 1,280 m high and thus Vesuvius-sized) that grew in a caldera also offset along the LOFZ and has distinct geochemistry from adjacent stratovolcanoes. Besides the clear seismic and volcanic hazard implications, the structural connection along the main trace of the fast slipping LOFZ and geochemistry of VMG provides evidence for the slab window and insight into interplay between fast-slipping crustal intra-arc crustal faults and volcanoes. DOI PubMed
4. Junquera-Torrado, S; Moreiras, SM; Rodriguez-Peces, MJ; Sepúlveda, SA.Linking earthquake-triggered paleolandslides to their seismic source and to the possible seismic event that originated them in a portion of the Argentine Precordillera (31 degrees-33 degrees S).Nat. Hazards, 2021, 106: 43-78 Linking earthquake-triggered paleolandslides to their seismic source and to the possible seismic event that originated them in a portion of the Argentine Precordillera (31 degrees-33 degrees S)
Slope stability analysis; 2D modelling; Active fault; Landslides; Precordillera; Argentina
A total of 36 rock slides were selected for analysing a probable seismic source in the active Andean Precordillera (31 degrees-33 degrees S), the most seismic region of Argentina. Seven of these slope instabilities were selected for in-depth analysis in the field as a function of the most frequent class, lithological susceptibility and field accessibility. Reconstructing the topography previous to collapse and using geotechnical parameters extracted from field data in conjunction with geomechanical testing, the rock slides were modelled using pseudostatic limit equilibrium analyses for the obtention of the critical probabilistic acceleration (a(c)) required to generate the instability under unsaturated conditions and considering both the horizontal and vertical seismic components. To perform a probabilistic estimation of a(c), the parameters in relation to the generalized Hoek-Brown failure criterion were selected to operate statistically using 2D SLIDE 8.0 software. Applying inversely Ground Motion Prediction Equations (GMPEs) and concerning the distance to the studied paleolandslide, a possible earthquake inducing a seismic coefficient (k(h)) >= a(c) was determined. Therefore, a near active fault(s) capable of generating an earthquake magnitude inducing a Peak Ground Acceleration (PGA) >= a(c) at the paleolandslide location was designated as the possible seismogenic source of the slope instability. Intersecting these results, potential paleoseismic events which could have caused several slope instabilities were determined. Thus, a new methodology was developed, which allowed to determine the main seismogenic sources capable of inducing the modelled instabilities in each studied subarea in the Precordillera. DOI
3. Moreiras, SM; Sepúlveda, SA; Correas-Gonzalez, M; Lauro, C; Vergara, I; Jeanneret, P; Junquera-Torrado, S; Cuevas, JG; Maldonado, A; Antinao, JL; Lara, M.Debris Flows Occurrence in the Semiarid Central Andes under Climate Change Scenario.Geosciences, 2021, 11 Debris Flows Occurrence in the Semiarid Central Andes under Climate Change Scenario
natural hazard; permafrost; feeding sediments; global warming
This review paper compiles research related to debris flows and hyperconcentrated flows in the central Andes (30 degrees-33 degrees S), updating the knowledge of these phenomena in this semiarid region. Continuous records of these phenomena are lacking through the Andean region; intense precipitations, sudden snowmelt, increased temperatures on high relief mountain areas, and permafrost degradation are related to violent flow discharges. Documented catastrophic consequences related to these geoclimatic events highlight the need to improve their understanding in order to prepare the Andean communities for this latent danger. An amplified impact is expected not only due to environmental changes potentially linked to climate change but also due to rising exposure linked to urban expansion toward more susceptible or unstable areas. This review highlights as well the need for the implementation of preventive measures to reduce the negative impacts and vulnerability of the Andean communities in the global warming context. DOI
1. Serey, A; Sepúlveda, SA; Murphy, W; Petley, DN; De Pascale, G.Developing conceptual models for the recognition of coseismic landslides hazard for shallow crustal and megathrust earthquakes in different mountain environments - an example from the Chilean Andes.Q. J. Eng. Geol. Hydrogeol., 2021, 54 Developing conceptual models for the recognition of coseismic landslides hazard for shallow crustal and megathrust earthquakes in different mountain environments - an example from the Chilean Andes
Landslides represent the most frequent geological hazard in mountainous environments. Most notably, landslides are a major source of fatalities and damage related to strong earthquakes. The main aim of this research is to show through three-dimensional engineer-friendly computer drawings, different mountain environments where coseismic landslides could be generated during shallow crustal and megathrust earthquakes in the Andes of central Chile. We have determined topographic, geomorphological, geological and seismic controlling factors in the occurrence of earthquake-triggered landslides from: (1) a comparison of local earthquake-induced landslide inventories in Chile (the M-w 6.2, shallow crustal Aysen earthquake in 2007 (45.3 degrees S) and the M-w 8.8, megathrust Maule earthquake in 2010 (32.5 degrees S-38.5 degrees S)) with others from abroad; and (2) analysis of large, prehistoric landslide inventories proposed as likely induced by seismic activity. With these results, we have built four representative geomodels of coseismic landslide geomorphological environments in the Andes of central Chile. Each one represents the possible landslide types that could be generated by a shallow crustal earthquake v. those likely to be generated by a megathrust earthquake. Additionally, the associated hazards and suggested mitigation measures are expressed in each scenario. These geomodels are a powerful tool for earthquake-induced landslide hazard assessment. Thematic collection: This article is part of the Ground models in engineering geology and hydrogeology collection available at: DOI
