Sergio A Sepúlveda

Simon Fraser University · Department of Earth Sciences

The link between large-volume landslides and a potential seismic source has not been extensively tackled in the seismic central Chile even though many mega-landslides have been triggered historically by earthquakes. In this research, an inventory of prehistoric landslides was developed on the western border of the Andes Principal Cordillera, identi...

The effects of deglaciation on the slope stability of glacial valleys have increasing importance in the context of climate change, as they may affect the susceptibility to large-volume landslides and catastrophic cascading geohazards. On December 16th, 2017, a massive rock slide near a retreating glacier evolved into a debris-mud flow that impacted...

Chile is one of the most seismically active countries on Earth and is often associated with cascading hazards, such as ground shaking, liquefaction, tsunamis, and coseismic landslides. Additionally, removal mass is a global hazard with devastating impacts resulting in thousands of fatalities every year, substantial economic losses, and long-term ec...

The Mount Meager Volcanic Complex/Qw ̓ elqw ̓ elústen (MMVC) is a glaciated system of coalesced stratovolcanoes which has experienced many landslides larger than 100,000 m 3. In this study, landslide susceptibility in the MMVC was studied at a massif scale using statistical methods and slope scale using physical methods. Statistical landslide susce...

Over the last 60 years, six landslides with volumes from 105 m3 to 5.3 × 107 m3 have occurred around Qwelqwelústen (Mount Meager Volcanic Complex; MMVC), southwestern British Columbia, Canada. The dormant volcanic massif has experienced significant uplift leading to exposed and incised Miocene and older basement rocks and volcanic rocks associated...

The occurrences of large rock slides often result in catastrophic debris flow within high mountain environments. Discontinuity intersected blocks meeting kinematic conditions stemming from deglaciation-related damage can be triggered by external factors, leading to massive rock slides with a significant downstream hazard. This study presents a comp...

Landslide natural hazards are frequently encountered in hilly terrains. In rock slides, the slope failure surface might be governed by different discontinuity sets, leading to a complex failure. Sometimes, it becomes difficult to determine the failure surface/depth even after the failure due to debris cover. Borehole or geophysical methods are comm...

Accurate estimation of joint roughness is critical for characterizing the mechanical and hydraulic properties of rock joints, thereby contributing to informed assessments of the rock mass classification, shear strength, and permeability estimates. The most prevalent way to quantify joint roughness is the Joint Roughness Coefficient (JRC). However,...

Debris flows are the extremely rapid (often channelized) movement of unconsolidated and saturated slope forming materials. Once triggered, these mass movements can gain enough momentum to destroy life and infrastructure exposed to their travel path. Exceptional historic debris flows have even killed thousands of people in one single event (for exam...

The mountainous regions are prone to multiple natural disasters. Landslides are one of the frequent hazards triggered by heavy rainfall, earthquake, or controlled by complex geological conditions. Characterizing the landslide failure surface and its volume provides a fundamental understanding of its behaviour and risk assessment. The failure surfac...

The Chilean Central Andes have been under severe hydrological stress due to the uninterrupted megadrought for the last 13 years. The region is known for being the denser populated zone of the country and it hosts a wide variety of glaciers along with the largest ice masses outside Patagonia.This work presents a susceptibility assessment for glacier...

In this paper, we study natural hazards and their potential impacts on productive activities in the Comau Fjord in Chilean Northern Patagonia. We carried out hazard mapping to identify areas with evidence of geomorphological activity on slopes in terms of landslides, river/tsunami flooding, and glacial retreat. The assessment of different geomorphi...

Large-volume rock slope failures are one of the main hazards in high mountain glaciated valleys, inducing severe damage to population and infrastructure, representing a high risk for society, ecosystems and infrastructure. The Andes Mountain Range is shaped by glacial activity and therefore by megalandslides due to changes in shear strength and def...

The assessment of earthquake-induced landslide susceptibility and hazard is a complex problem, as it must consider elements from both the geological and geotechnical properties of the slope and strong ground motion parameters from expected earthquakes scenarios. In recent decades, quantitative and computing tools have quickly developed and are incr...

The 2007 Aysen earthquake, of magnitude Mw 6.2, was a shallow crustal earthquake in the large, regional Liquiñe-Ofqui Fault Zone. It triggered a total of 541 landslides (reported) classified as rock slides and avalanches, rock falls, shallow soil and soil-rock slides, and debris flows. The largest landslides induced a local tsunami in the Aysen fjo...

An unusually intense atmospheric river affected the southern coastal region of British Columbia in mid-November 2021. Flooding and several ground failures such as landslides and riverbank erosion caused significant damage and interrupted the main transportation corridors, including major highways and railroads, severing land connectivity between Me...

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 catalog...

A landslide cluster located in the Pangal river valley, Cachapoal river basin, in the Andes of central Chile is investigated. Deposits of five rock avalanche deposits of volumes varying from 1.5 to 150 million cubic metres are distinguished by detailed geomorphological mapping and dating. The landslides were originated in volcanic rocks affected by...

Earthquakes trigger widespread landsliding in tectonically active landscapes. The effects of strong ground shaking on hillslope stability persist into the post‐seismic stage; rates of landsliding remain elevated in the years following an earthquake. The mechanisms that control the spatial pattern and rate of ongoing landsliding are poorly constrain...

Understanding the location and nature of Quaternary active crustal faults is critical to the reduction of both fault rupture and strong ground motions hazards in the built environment. Recent work along the San Ramon Fault in Santiago, Chile demonstrates that crustal seismic sources are important hazards. We present the results of a second likely Q...

The southernmost portion of the Liquiñe-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...

A total of 36 rock slides were selected for analysing a probable seismic source in the active Andean Precordillera (31°–33°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. Recons...

This review paper compiles research related to debris flows and hyperconcentrated flows in the central Andes (30°-33° S), updating the knowledge of these phenomena in this semiarid region. Continuous records of these phenomena are lacking through the Andean region; intense pre-cipitations, sudden snowmelt, increased temperatures on high relief moun...

Arid and semi-arid complex environments display particular characteristics with an ensemble of different factors that can facilitate slope failures and mass movement. Poor soil development, intense physical weathering, intense storms, droughts, and wind particles deposition in these climatic environments provide the stage on which the landslides ar...

A ca. 2.5 million m3 landslide occurred in August 2018 in the Yerba Loca valley, Andes Main Cordillera (33° 15′ S), at about 4000 m a.s.l. The Yerba Loca landslide is a multirotational slide, with a main scarp and failure surface developed in a volcanic rock mass, with secondary scarps and tilted blocks disturbing the colluvial soil cover. No clear...

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 c...

We address the question of whether all large‐magnitude earthquakes produce an erosion peak in the subaerial components of fluvial catchments. We evaluate the sediment flux response to the Maule earthquake in the Chilean Andes (Mw 8.8) using daily suspended sediment records from 31 river gauges. The catchments cover drainage areas of 350 to around 1...

As one of the main environmental effects of earthquakes, the distribution of landslides could reflect regional neotectonic activity. To that end, we carried out an inventory of landslides along the Precordillera range (31°-33°S) comprising the most seismically active region of Argentina. Main Quaternary deformation is concentrated in this Western c...

The 2010 Mw=8.8 Maule earthquake, which occurred in the subduction contact between the Nazca and the South American tectonic plates off the coast of Chile, represents an important opportunity to improve understanding of the distribution and controls for the generation of landslides triggered by large megathrust earthquakes in subduction zones. This...

A geomorphological analysis of the Comau Fjord was carried out to identify geohazards that are a product of current landform dynamics and processes. The geological setting of the area includes fractured metamorphic and volcanic rocks forming steep hillslopes in an active tectonic context due to the Liquiñe-Ofqui Fault Zone (LOFZ). Geomorphological...

The urban expansion of Santiago city includes areas with geomorphological and geological conditions with potential to be affected by landslide processes. This work presents compiled landslide susceptibility maps for the Andean foothills of Santiago city, between Maipo and Mapocho rivers. The maps identify the areas prone to the generation of slides...

In this paper, static and dynamic analyses were performed considering the reconstituted geometry of a prehistoric 0.1 km² rockslide with an exposed stepped-planar failure surface using a distinct element code (UDEC®). The rockslide occurred on the northern slope of the Cerro Catedral mount, located in the headers of the Maipo river drainage basin (...

A geomorphological analysis of the Comau Fjord was carried out to identify geohazards that are a product of current landform dynamics and processes. The geological setting of the area includes fractured metamorphic and volcanic rocks forming steep hillslopes in an active tectonic context due to the Liquiñe-Ofqui Fault Zone (LOFZ). Geomorphological...

Two micro-catchments, tributaries of the Elqui River in the coastal range of the semiarid central-northern Chile were analyzed to establish the hazard potentials associated with extreme rainfall and their effects on the urban area of La Serena city. Geomorphological mapping was performed identifying the morphological features associated with inheri...

The study area is located along the Andean active orogenic front comprising the most seismically active region of Argentina. Main Quaternary deformation is concentrated in this Western central part of the country associated with active faults linked to an intense shallow seismic activity (<30 km depth). During the last 150 years, the region has suf...

Two micro-catchments, tributaries of the Elqui River in the coastal range of the semiarid central-northern Chile were analyzed to establish the hazard potentials associated with extreme rainfall and their effects on the urban area of La Serena city. Geomorphological mapping was performed identifying the morphological features associated with inheri...

For a proper risk assessment it is necessary to consider all parameters and variables that play an important role in a particular phenomenon. For the case of co-seismic rock slides, we believe that current methodologies for stability analysis do not accomplish that goal, given the lack of information in their models, which leads to uncertainties in...

Rock avalanche clusters can be relevant indicators of the evolution of specific regions. They can be used to define: the type and intensity of triggering events, their recurrence and potential probability of occurrence, the progressive damage of the rock mass, the mechanisms of transport and deposition, as well as the environmental conditions at th...

We used a distinct element code (UDEC ®) to perform a dynamic numerical analysis of a 0.1 km 2 rock slide with a stepped-planar failure surface. The failure occurred on the northern slope of Cerro Catedral hill, located in the headers of the Maipo river drainage basin (Andes Cordillera) at the latitude of the Santiago city (33 • S). The failure sur...

Analyses of three case studies of earthquake-induced rock slides in central and southern Chile are presented. The case studies are located in different latitudes, local tectonic environments, and geomorphological contexts of the Andes (Santiago Main Cordillera at 33ºS, Concepción Coastal Cordillera at 37ºS, and Patagonia Fjordland at 45ºS), with di...

The co-seismic and post-seismic behaviour of pyroclastic ash deposits and its influence on slope stability remains as a challenging subject in engineering geology. Case studies in volcanic areas of the world suggest that soil structural changes caused by seismic shaking results in landslide activity. It is critical to constrain how this kind of soi...

Landslides caused by earthquakes have been extensively studied in different parts of the world, in different geodynamic settings. In our case, the February 27, 2010, an Mw 8.8 megathrust earthquake severely hits the coasts of south-central Chile, with a rupture zone of more than 450 km. long producing landslides along the coastal range and coastal...

A series of novel seismic and landslide hazard studies funded by the Chilean Housing and City Planning Ministry were carried out in the Santiago Metropolitan Region in the aftermath of the 2010 Chile earthquake by university geoscientists and urban planning consultants. The studies aimed to suggest modifications of urban planning regulating plans....

A new data set of landslides that caused loss of life in Latin America and the Caribbean in the 10-year period from 2004 and 2013 inclusive has been compiled, providing new insight into the impact of landslides in this key part of the world. This data set indicates that in the 10-year period a total of 11 631 people lost their lives across the regi...

A database of landslides that caused loss of life in Latin America and the Caribbean in the period from 2004 and 2013 inclusive has been compiled using established techniques. This database indicates that in the ten year period a total of 11 631 people lost their lives across the region in 611 landslides. The geographical distribution of the landsl...

This work presents the results of a regional-scale estimation of low-enthalpy geothermal resources for district heating in the Santiago basin. The purpose of this work is to identify promising areas for the development of this type of renewable energy. The estimation was based on comparison of soil thermal properties and hydrogeological parameters,...

The Aysén fjord, 65 km long and east-west oriented, is located at 45.4ºS and 73.2ºW in Chilean Patagonia. It has a maximum water depth of 345 m. It collects the inputs of Aysén, Pescado, Condor and Cuervo rivers, which drain the surrounding Patagonian Andes. The fjord is crossed by the Liquiñe-Ofqui Fault Zone, a seismically active trench parallel...

The Tongoy bay (30°S/70°30'W) and the related catchment system in the western fringe of the semiarid Chilean Coastal Cordillera consists of an inherited landscape subject to present-day geomorphic processes. It is an interactive morphological system, formed by coastal range watersheds, marine terraces and sandy beaches. Taking into account the geol...

In March 2012, during the rainy season in the Altiplano plateau, a >100-year return period rainfall event affected the deeply incised valleys of the Precordillera of the Tarapacá Region, northern Chile. This extreme event in a very arid region triggered a number of debris and mud flows that caused severe damage and destruction in several small vill...

This review deals with an integration and update of the knowledge about large-volume landslides in the Central Andes at 32-34°S. An integrated landslide inventory for megalandslides in central Chilean and Argentinean Andean basins was developed, and dispersed chronological data on palaeolandslides were compiled, showing a dominance of Late Pleistoc...

The Aysén fjord is a 65 km long, east-west oriented fjord in Chilean Patagonia, located approximately at 45.4ºS and 73.2ºW, with a maximum water depth of 345 m. The fjord receives at present the riverine input of Aysén, Pescado, Condor and Cuervo rivers, which drain the surrounding up to 2000 m high Patagonian Andes. The fjord is crossed by a numbe...

The Andes, the world's largest non-collisional orogen, is considered the paradigm for geodynamic processes associated with the subduction of an oceanic plate below a continental plate margin. In the framework of UNESCO-sponsored IGCP 586-Y project, this Special Publication includes state-of-the-art reviews and original articles from a range of Eart...

In January and February 2013, heavy rainfall during local summer storms triggered a large number of landslides in the Andes Main and Frontal ranges of central Chile and Argentina (32°–34° S). Most of the mass movements classify as debris flows, while rockfalls and debris avalanches also occurred. The major debris flows occurred in the Maipo and Aco...

The Mesón Alto chaotic deposit, located in the Main Cordillera at about 33°40’S, is an important landform with a volume of ca. 4.5 km3 unconsolidated material deposited downstream of the Yeso Dam in the Yeso Valley, Río Maipo drainage basin. Historical work related this large deposit to a glacial origin whereas later on, it was assigned to a megala...

On 21 April 2007 (Mw 6.2) an earthquake triggered more than 500 landslides near the epicenter along the Aysén fjord, Chile. One of the major failures occurred at the Punta Cola Valley involving a volume of 20.9 million cubic meters of rock. The main rockslide was followed by a rock/debris avalanche involving talus and glacio-fluvial deposits in the...

For conceptual purposes Redfield & Osmundsen (2009) proposed a two-end-member rockslide categorization scheme that reflects Norway's extended margin architecture. Type 1 slides are comprised by compartments that incorporate extensively-developed fault-rock fabrics whose origins can be directly traced to regional-scale, through-going, brittle-phase...

The Tongoy bay (30ºS/70º30’W) and the related catchment system in the western fringe of the semiarid Chilean Coastal Cordillera consists of an inherited landscape subject to present-day geomorphic processes. It is an interactive morphological system, formed by coastal range wa- tersheds, marine terraces and sandy beaches. Taking into account the ge...

Chile is one of the most seismically active countries in the world, having witnessed several large earthquakes that produced human and material losses; seismic hazard estimation is one of the most used tools to prevent such losses. The present study reviews the state-of-the-art of the probabilistic seismic hazard, comparing 3 different approaches a...

On 21 April 2007, an Mw 6.2 earthquake produced an unforeseen chain of events in the Aysén fjord (Chilean Patagonia, 45.5°S). The earthquake triggered hundreds of subaerial landslides along the fjord flanks. Some of the landslides eventually involved a subaqueous component that, in turn, generated a series of displacement waves—tsunami-like waves p...

The Liquiñe-Ofqui fault zone (LOFZ) in the Patagonian Andes is an active major transpressional intra-arc fault system along which Quaternary faulting and volcanism develop. Subaerial and submarine geomorphologic and structural characterization of latest Pleistocene-Holocene faults and monogenetic volcanoes allows us to assess geological cartography...

This review deals with an integration and update of the knowledge about large-volume landslides in the Central Andes at 32– 348S. An integrated landslide inventory for megalandslides in central Chilean and Argentinean Andean basins was developed, and dispersed chronological data on palaeolandslides were compiled, showing a dominance of Late Pleisto...

Large landslides are a common geomorphological feature of the Central Andes of Chile and Argentina. The highlands usually present landslide relicts of different types and volumes located in glacial valleys, including outsized rock slides and avalanches of millions of cubic metres up to cubic kilometres of volume. Even though the main trigger mechan...

Composite maps have previously been applied to paleogeographic reconstructions and as an aid to mineral exploration. However, because they can combine different criteria that are used in risk and feasibility assessment into a single map with equal or weighted input from all the parameters, decisionmaking can be optimized. The methodology is particu...

Large volume rock slides and rock avalanches are common in the highlands of the Andes of central Chile and Argentina. Most of them have failed with a massive failure mode. An exception is a 0.7 km 2 rock slide with a clear plane failure mode on two major steps found in the headers of the Maipo river drainage basin at the latitude of Santiago (33ºS)...