Marcelo Farias

• PhD
• Professor (Assistant) at University of Chile

Seismograms of about 12,000 aftershocks of the Mw6.7 Coquimbo-La Serena earthquake of 20 January 2019 that were recorded during six months by an array of 33 short-period seismic stations are used to generate wavespeed images of the subduction wedge beneath the Chilean forearc between 28.0°-30.6°S. This part of the margin is near the northern termin...

We analyze records of ambient seismicity from Central Chile to investigate mechanisms of tectonic erosion and accretion in an Andean margin. The seismograms were recorded by a temporary network of 39 stations deployed between 32.5°S and 34.0°S from April to November 2017. We employ an automatic earthquake catalogue generator to estimate 8463 P-wave...

We present an interpretation of how natural geological and meteorological events influenced the cosmovision of the Mapuche people from south-central Chile. These events resulted from the geodynamic conditions and related processes occurring along the South American active continental margin and the climatic conditions in the region. Their influence...

Following the Mw 8.8 Maule megathrust earthquake that occurred on February 27, 2010, in central Chile, a sequence of normal faulting crustal earthquakes occurred close to the city of Pichilemu. This activity lasted several months and included two large events (Mw = 6.9 and Mw = 7.0) on March 11, 2010. An initial investigation of this activity analy...

The Maastrichtian-Danian transgression was one of the most extensive Atlantic-derived marine incursions in Patagonia. This study examines its stratigraphic record and origin in the Magallanes-Austral Basin, revealing an interplay of sedimentation, tectonism, and base-level changes, which contribute to our understanding of foreland basin dynamics. W...

We document the effects of major mid‐Cretaceous to Late Cretaceous compression within the volcanic arc of the western Gondwanan margin. The thinned Early Cretaceous Andean margin underwent rapid thickening and shortening‐related exhumation of magmatic arc rocks during compressional inversion of late Early Cretaceous intra‐arc basins. Clastic sedime...

U–Pb dating of detrital and igneous zircons from the retroarc deposits of the Neuquén Basin has shed light over the Mesozoic evolution of the western border of South America, yet the coeval arc and forearc regions remain mostly indirectly characterized. Furthermore, recent paleogeographic reconstructions consider the arc and forearc regions as a te...

Intense storms or earthquakes in mountains can supply large amounts of gravel to rivers. Gravel clasts then travel at different rates, with periods of storage and periods of displacement leading to their downstream dispersion over millennia. The rate of this dispersion controls the long-term downcutting rate in mountainous rivers as well as the gra...

Este es un póster sobre lo que realicé en mi Memoria de Título. Contiene de forma muy resumida, algunos de los resultados destacables y/o notables de mi tesis.

The scarce Eocene geological record in the Andean region of Central Chile ( c. 33.6° S) is represented by the Estratos del Cordón de los Ratones unit. This is a c. 450 m thick, mainly volcanic, continental series with a bimodal character that hosts numerous subvolcanic intrusions. The igneous products show compositional features indicating a co-gen...

In central Chile (33°50'-34°30'S), the Quaternary arc records a distinctive episode of silicic volcanism (SiO2 >70 wt.%) that occurred during latest Pleistocene (0.1-1 Ma). This episode is recorded in several eroded and inactive arc centers distributed mostly along the highest summits of the Andes in the same region covered by the modern arc center...

Aftershocks of the 16 September 2015 M8.3 Illapel earthquake in central Chile were recorded for a period of one year by the Chile-Illapel Aftershock Experiment (CHILLAX) seismic network. An initial catalog of about 100,000 events was generated by a novel automated picking algorithm that combines an auto-regressive detection/onset estimation method...

El bloque de San Rafael corresponde a un bloque de basamento ubicado al este de la Cordillera Principal, cuyo alzamiento habría ocurrido post- 6 Ma asociado a la fragmentación de la cuenca de país neógena. Previo a esto y durante el Mioceno se depositó sobre el bloque San Rafael una secuencia sedimentaria denominada Fm. Aisol. De acuerdo a las edad...

The Abanico basin system is a major paleogeographic feature developed along the Andean margin after a regional scale extensional event during the late Eocene-early Miocene [1]. This corresponded to an intra-arc extensional and subsiding basin that accumulated more than 3.000 m of arc deposits over a ~35 km thick crust. Although the basin system dev...

New thermochronometric data provide evidence for an along-strike diachronous building of the Andes in north-central Chile (28.5–32°S). Geochronological (U-Pb zircon) and thermochronological (apatite fission track and (U-Th)/He) analyses of rock units were obtained in west-to-east transects across the western topographic front. Thermal models indica...

The study of Late Cretaceous-earliest Paleogene series in the Chilean Andes at ~35°S provides new constraints on the coeval evolution of the area and the Southern Central Andes. These correspond to the continental series of BRCU and the overlying Plan de los Yeuques Formation (PYF). Zircon age determinations reveal that these represent an almost co...

Structural evolution of the southernmost Central Andes is a major subject of debate. Overall vergence within the range and how intra-continental subduction prompts Andean orogeny are controversial topics. Between 33°-35° S, strike of the western slope main structures shifts southwards, from N-S to NNE-SSW, defining the Maipo Orocline. Likely, width...

The infill of the Neuquén Basin recorded the Meso-Cenozoic geological and tectonic evolution of the southern Central Andes being an excellent site to investigate how the pattern of detrital zircon ages varies trough time. In this work we analyze the U-Pb (LA-MC-ICP-MS) zircon ages from sedimentary and volcanic rocks related to synrift and retroarc...

Resumen. Se analiza el control de la estructura del basamento de Cuenca Neuquina en el desarrollo de las fajas plegadas y corridas de Aconcagua y Malargüe junto con las características actuales del orógeno, al sur del segmento de subducción plana (33°30'S). Estimaciones del acortamiento tectónico muestran que ambas fajas acomodaron cantidades simil...

En el borde occidental de los Andes, en Chile central, el alzamiento del relieve es consecuencia de la inversión tectónica de la Cuenca de Abanico, en la que se acumularon sucesiones volcano-sedimentarias asignadas a las formaciones cenozoicas Abanico y Farellones. En base a la integración de datos de terreno, modelamiento estructural e información...

The Andean internal zone records deformation, uplift and erosion that serve as proxies of variations on mountain building dynamics. Hence, the study of this region would give keys to understand the factors controlling the orogenic evolution. Structural, stratigraphic and geochronological data in the Andean internal zone at 35°20'S evidence that thi...

The effect of mean precipitation rate on erosion is debated. Three hypotheses may explain why the current erosion rate and runoff may be spatially uncorrelated: (1) the topography has reached a steady state for which the erosion rate pattern is determined by the uplift rate pattern; (2) the erosion rate only depends weakly on runoff; or (3) the stu...

The Andean building has been traditionally considered as a consequence of successive orogenic phases mostly occurring during the Cenozoic. However evidence from Peru-northern Chile and southern Argentina have shown a first contractional pulse during the mid to late Cretaceous. Between these regions, however, there are no reports evidencing this eve...

Las condiciones paleogeográficas y tectónicas que existían en Chile central durante el Cretácico tardío han sido fuente de controversia. Si bien las potentes secuencias volcánicas ubicadas en la Cordillera de la Costa testifican la existencia de un evento extensional y de arcos volcánicos continuos desde el Jurásico al Cretácico Temprano (Charrier...

The effect of mean precipitation rate on erosion is debated. Three hypotheses may explain why the current erosion rate and runoff may be spatially uncorrelated: (1) the topography has reached a steady state for which the erosion rate pattern is determined by the uplift rate pattern; (2) the erosion rate only depends weakly on runoff; or (3) the stu...

A review of available stratigraphic, structural, and magmatic evolution in northernmost Chile, and adjacent Peru and Bolivia shows that in this region: (1) compression on the Paleogene intra-arc during the middle Eocene Incaic phase formed the NNE-SSW-oriented Incaic range along the present-day Precordillera and Western Cordillera, and (2) post-Inc...

The analysis of new and published Hf and Nd isotopic data of late Cenozoic Andean arc igneous rocks from central Chile, coupled with our improved knowledge of orogenic processes in the region, reveals a tight link between major magmatic isotopic shifts and different Andean basement domains and timing of the main uplifting event. Oligo cene–Miocene...

The study of the Las Tunas River incisions, located in the eastern Andean foreland front (33�20'S in Argentina) provides new clues for the interpretation of deep piedmont entrenchments. Both the Las Tunas mountain catchment and its piedmont are strongly entrenched with maximal incision of over 100 m at the mountain front. Three main terrace levels...

Climate and topography control millennial-scale mountain erosion, but their relative impacts remain matters of debate. Conflicting results may be explained by the influence of the erosion threshold and daily variability of runoff on long-term erosion. However, there is a lack of data documenting these erosion factors. Here we report suspended-load...

En los cuadrángulos de Camiña, Cerro Socora, Mauque y Pisiga-Chile, se describe preliminarmente la geología de la Precordillera y Cordillera Occidental entre los 19º15’ y 19º30’S. En ellas se observan estructuras pertenecientes al West-Vergent Thrust System y EastVergent Thrust System que implicaron directamente la morfología de la zona durante el...

We report a sequence of crustal quakes that began after the Mw = 8.8 thrust-subduction Maule earthquake that affected the Central Chile margin on 27 February 2010. This activity lasted by several months, having the most important events on 11 March 2010 (Mw = 6.9 and Mw = 7.0) with normal focal mechanisms. Seismicity shows a rupture oriented along...

Short-term and long-term erosion rates in Chile

Major fluvial incision (600-1000 m) affecting the Coastal Cordillera and Central Depression of northern Chile is analysed to evaluate supposed coeval uplift of the Altiplano and/or climatic changes in the Atacama Desert. The timing of the beginning of incision is constrained by the age of deposition of the Central Depression top. In the north (18-1...

Levantamiento cosísmico e impacto del tsunami a lo largo de la costa de Chile central asociado al terremoto del Maule Mw8,8 de 2010. El 27 de febrero de 2010 a las 03:34:08 de la madrugada un terremoto de magnitud Mw8,8, cuyo epicentro se ubicó costa afuera de Cobquecura (73,24°W; 36,29°S), afectó severamente la zona centro-sur de Chile. Posteriorm...

On February 27, 2010 at 03:34:08 AM an Mw8.8 earthquake, with epicenter located off Cobquecura (73.24°W; 36.29°S), severely hit Central Chile. The tsunami waves that followed this event affected the coastal regions between the cities of Valparaíso and Valdivia, with minor effects as far as Coquimbo. The earthquake occurred along the subduction of t...

The Mw=8.8 Chilean megathrust earthquake of 27 February 2010 ruptured an interplate zone extending nearly 500 km along the coast of central Chile. Contrary to expectations, there has not been any major aftershock associated with the main rupture. Instead, the largest postseismic events thus far, a Mw=6.9 and a Mw=7.0 that occurred within 15 minutes...

We observed vertically displaced coastal and river markers after the 27 February 2010 Chilean earthquake [moment magnitude (Mw) 8.8]. Land-level changes range between 2.5 and -1 meters, evident along an approximately 500-kilometers-long segment identified here as the maximum length of coseismic rupture. A hinge line located 120 kilometers from the...

We document a crustal-scale structural model for the central Chile Andes based on seismicity and surface geology, which consists in a major east verging ramp-detachment structure connecting the subduction zone with the cordillera. The ramp rises from the subducting slab at ˜60 km depth to 15-20 km below the western edge of the cordillera, extending...

Located along the west coast of subtropical South America, the Atacama Desert features an extremely dry climate in sharp contrast with relatively wet conditions over the Central Andes and farther east. The Atacama's hyperaridity has been attributed to its subtropical location, the cold waters over the adjacent southeast Pacific Ocean and the presen...

The Chilean Andes extend north–south for about 3000 km over the subducting Nazca plate, and show evidence of local rheological controls on first-order tectonic features. Here, rheological parameters are tested with numerical models of a subduction driven by slab-pull and upper plate velocities, and which calculate the development of stress and stra...

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The Incaic orogeny created significant geographical relief during the Middle Eocene, along most of the area of the preceding magmatic arc, the Incaic Cordillera. This NNE-trending elevated terrain extended from southern Peru to central Chile and formed the boundary between two paleogeographical domains with dissimilar geological evolutions during t...

One of the most prominent tectonic features of the Andes is the Central Andean Rotation Pattern (CARP), which is closely related to the Bolivian Orocline and characterized by paleomagnetically determined clockwise rotations in northern Chile and counterclockwise rotations in southern Peru (Arriagada et al., 2008). Along the Chilean margin, between...

1] We explore the extent to which it is possible to convert erosion rate data into uplift rate or erosion laws, using a landscape evolution model. Transient stages of topography and erosion rates of a block uplifting at a constant rate are investigated at different spatial scales, for a constant climate, and for various erosion laws and initial top...

A theoretical framework is still lacking to interpret erosion rate data at differing spatial scales in active mountains in terms of erosion laws, climate or tectonics for transient landscapes. We explore the extent to which it is possible to convert erosion rate data into uplift rate or erosion laws, using a landscape evolution model. Transient sta...

The western Principal Cordillera consists of thick volcanic successions accumulated in an extensional basin and deformed in Early Neogene times during tectonic inversion of the basin. In the study region, key-layers are lacking and, for this reason, geometrical reconstructions are difficult. The main structure is a N-S-oriented syncline bounded by...

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Most of the seismological research in the Andes has been mainly oriented to the detection and understanding of the seismicity associated with megathrust earthquakes that characterize the subduction environment that governs the Andean tectonics. However, deployments of temporary networks have allowed the detection of intense crustal seismicity benea...

We address the question of the late Cenozoic geomorphological evolution of the central Chile Andes (33°–35°S), using uplift markers, river incision, previous and new ages of volcanic bodies, and new fission track ages. The uplift markers consist of relicts of high elevated peneplains that evidence >2 km of regional surface uplift lasting ∼2 Ma with...

We present a structural analysis of strongly deformed Cenozoic volcanic rocks of the western Principal Cordillera between 34°15'S and 34°30'S. Deformation has been related to the inversion of the Abanico Basin occurred between 22 and 16 Ma. The structural array is characterized by a syncline with a very steep western limb and a rather flat slightly...

The structural evolution related to the uplift of the Andean Cordillera between 33 and 35ºS is well known in the eastern Argentinean flank of the belt, in which it has been developed an east vergent thrust system. In turn, deformation in the Chilean flank of the chain has not been very well constrained and several discrepancies exist in order to ex...

Les structures tectoniques responsables du soulèvement de la Cordillère des Andes à la latitude de Santiago du Chili sont bien connues sur le versant argentin de la chaîne, où s’est développé au cours du Néogène un système chevauchant à vergence Est. Sur le flanc Pacifique de la Cordillère, par contre, les structures tectoniques sont mal connues, e...

Extensional basin development (Middle?-Late Eocene to Early Miocene), basin inversion and deformation of the basin fill (Early to Late Miocene) and rapid, high magnitude surface uplift (Late Miocene to Recent) characterize the Cenozoic tectonic evolution of the central Chilean Principal Cordillera, between 33° and 36°S. Extension (Abanico Basin) wa...

The last best documented historical large earthquakes in the Copiapo region (27°S) occurred on 1819, Mw=8.3 and 1922, Mw=8.5. The 1983, Mw=7.4 earthquake ruptured the northern segment of the 1922 large earthquake, stopping its rupture in the same region where the 1973 seismic swarm happens. By the end of April, 2006 four thrust events with magnitud...

We analyze the erosional evolution and relief growth of the Central Chile Andes (33-35°S) based on markers of incision, fission-track thermochronology and drainage basin analysis. Our results evidence a regional surface uplift of >1.5 km in ~2 m.y., including the entire forearc (offshore forearc, Coastal Cordillera and Central Depression) and mount...

We analyze the west vergent thrust system (WTS) along the western flank of the Altiplano in northern Chile (18°S–21°S). In our study area (19°20′S–19°50′S), the WTS consists of three thrust propagation monocline folds (flexures) developing growth strata. The relative uplift accommodated by the flexures is rapid between 26 and 8 Ma (0.1 mm/yr), dimi...

Seismic registration with the permanent local seismic network in central Chile and a temporary seismic network deployed along the Las Leñas and Pangal river valleys (34° 25'S) between January and May, 2004 permitted to better constrain the abundant shallow intra-continental seismicity previously detected in that region. Although most of the seismic...

The western slope of the Altiplano, in Northern Chile, is characterized by the existence of west-vergent thrust-systems. In the study region (Aroma area, 19 °25'S-19°45'S), three N25°W-trending flexures related to the activity of west-vergent thrust-faults were mapped. In the core of one of these flexures, a N25°W oriented blind thrust-fault dippin...

The only region in Chile where significant superficial continental crustal seismicity has been reported is the northernmost part of the country, above Iquique and Arica, where a permanent seismic network is operating since 1994. Data show that the crustal seismicity vanishes south of 19.7S. This region is located in front of the north Chile seismic...