Andrés Rivera

Andrés Rivera
University of Chile · Departamento de Geografía

Doctor of Philosophy

About

227
Publications
67,481
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8,830
Citations
Citations since 2017
59 Research Items
3922 Citations
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20172018201920202021202220230100200300400500600
20172018201920202021202220230100200300400500600
Introduction
Glaciology

Publications

Publications (227)
Article
Full-text available
The Southern Patagonian Icefield (SPI) is the largest continuous ice mass in the Southern Hemisphere outside Antarctica. It has been shrinking since the Little Ice Age (LIA) period, with increasing rates in recent years. An uplift of crustal deformation in response to this deglaciation process has been expected. The goal of this investigation is to...
Chapter
This chapter addresses the distribution and characteristics of the Patagonian glaciers together with their recent changes and hydrological implications. Recently published national glacier inventories for the Andes between ca. 37 °S and 55 °S indicate that this region contains 24,000 ice masses covering ca. 26,100 km2. This includes the Southern Pa...
Article
Full-text available
Los investigadores navegaron el lago Viedma en una embarcación de la Administración de Parques Nacionales de Argentina con la que se realizó un levantamiento detallado del fondo del lago, para sorpresa de los investigadores el fondo presenta una fosa que alcanza una profundidad máxima de 900 m ±3% de error. Es un récord absoluto en Patagonia y Suda...
Research
Full-text available
En una expedición realizada al Parque Nacional Los Glaciares (PNLG) de la Patagonia austral argentina en mayo del 2022 por investigadores del Lab. de Geomática Andina-IANIGLA, CONICET-Argentina (María Gabriela Lenzano, Esteban Lannutti y Silvana Moragues), del Centro Internacional de Ciencias de la Tierra (ICEs-Regional Cuyo)-Universidad Nacional d...
Article
Full-text available
Glaciers in the Southern Patagonia Icefield (SPI) have been shrinking in recent decades, but due to a lack of field observations, understanding of the drivers of ablation is limited. We present a distributed surface energy balance model, forced with meteorological observations from a west–east transect located in the north of the SPI. Between Octob...
Article
Full-text available
We have investigated the source and role of light-absorbing impurities (LAIs) deposited on the glaciers of the Olivares catchment, in Central Chile. LAIs can considerably darken (lowered albedo) the glacier surface, enhancing their melt. We combined chemical and mineralogical laboratory analyses of surface and ice core samples with field-based spec...
Article
Identifying the source mechanisms of low-frequency earthquakes at ice-covered volcanoes can be challenging due to overlapping characteristics of glacially and magmatically derived seismicity. Here we present an analysis of two months of seismic data from Llaima volcano, Chile, recorded by the permanent monitoring network in 2019. We find over 2000...
Article
Full-text available
Blue ice is found in areas of Antarctica where katabatic winds, focussed by steep surface slopes or by topography around nunataks, cause enhanced surface ablation. This process draws up deeper, older ice to the ice sheet surface, often bringing with it englacial sediment. Prevailing theories for dynamically stable moraine surfaces in East Antarctic...
Article
Full-text available
Current climatic conditions in Central Andes (CA) (31-36 °S) have triggered the reduction of glacier area. Although CA are geographically circumscribed to an area under the same macroclimatic domain, their rugged topography creates several topoclimates as response to the effects of elevation, slope and aspect (morphometric factors). This study expl...
Preprint
Identifying the source mechanisms of low-frequency earthquakes at ice-covered volcanoes can be challenging due to overlapping characteristics of glacially and magmatically derived seismicity. Here we present an analysis of two months of seismic data from Llaima volcano, Chile, recorded by the permanent monitoring network in 2019. We find over 2,000...
Article
Full-text available
Glaciation and deglaciation modify the stress of the slopes affected by these processes and can trigger their instability and landslides. This study describes, characterizes and reconstructs a large rotational landslide of soil and moraine material, which occurred on February 10, 2013 on the western slope of Upsala Channel, North Branch of Argentin...
Article
Full-text available
A number of glaciological observations on debris-covered glaciers around the globe have shown a delayed length and mass adjustment in relation to climate variability, a behavior normally attributed to the ice insulation effect of thick debris layers. Dynamic interactions between debris cover, geometry and surface topography of debris-covered glacie...
Poster
Full-text available
The Southern Patagonia Icefield (SPI) is the largest continuous ice mass in Southern Hemisphere outside Antarctica. It has been shrinking since the little Ice Age (LIA) period with increasing rates in recent years. In response to this deglaciation process an uplift crustal deformation has been expected. We addressed this hypothesis by installing tw...
Article
Full-text available
Subglacial water plays an important role in ice sheet dynamics and stability. Subglacial lakes are often located at the onset of ice streams and have been hypothesised to enhance ice flow downstream by lubricating the ice– bed interface. The most recent subglacial-lake inventory of Antarctica mapped nearly 400 lakes, of which �14% are found in West...
Article
Full-text available
We acknowledge the priority on the introduction of the formula of t-lgHill estimator for the positive extreme value index. We provide a novel motivation for this estimator based on ecologically driven dynamical systems. Another motivation is given directly by applying the general t-Hill procedure to log-gamma distribution. We illustrate the good qu...
Article
Full-text available
Reply to the comments by Kochtitzky and Edwards (2020) on the study ‘Area changes of glaciers on active volcanoes in Latin America’ by Reinthaler and others (2019) - Johannes Reinthaler, Frank Paul, Hugo Delgado Granados, Andrés Rivera, Christian Huggel
Article
Full-text available
Glacier ice thickness is crucial to quantifying water resources in mountain regions, and is an essential input for ice-flow models. Using a surface velocity inversion method, we combine ice thickness measurements with detailed surface elevation and velocity data, and derive ice thickness and volume estimates for the Monte Tronador glaciers, North P...
Conference Paper
The future response of the Antarctic ice sheet to rising temperatures remains highly uncertain. A useful period for assessing the sensitivity of Antarctica to warming is the Last Interglacial (LIG) (129 to 116 ky), which experienced warmer polar temperatures and higher global mean sea level (GMSL) (+6 to 11 m) relative to present day. LIG sea level...
Article
Full-text available
The Southern Ocean occupies 14% of the Earth’s surface and plays a fundamental role in the global carbon cycle and climate. It provides a direct connection to the deep ocean carbon reservoir through biogeochemical processes that include surface primary productivity, remineralization at depth and the upwelling of carbon-rich water masses. However, t...
Article
Full-text available
The Andes Cordillera contains the most diverse cryosphere on Earth, including extensive areas covered by seasonal snow, numerous tropical and extratropical glaciers, and many mountain permafrost landforms. Here, we review some recent advances in the study of the main components of the cryosphere in the Andes, and discuss the changes observed in the...
Preprint
Full-text available
Abstract. Subglacial water plays an important role in ice sheet dynamics and stability. It is often located at the onset of ice streams and has the potential to enhance ice flow downstream by lubricating the ice-bed interface. The most recent subglacial lake inventory of Antarctica mapped nearly 400 lakes, of which ~ 14 % are found in West Antarcti...
Article
Full-text available
Glacially- and magmatically-derived seismic events have been noted to heavily overlap in characteristics, thus there exists the potential for false-alarms or missed warnings at ice-covered volcanoes. Here we present the first study to specifically target icequakes at an ice-covered volcano in Southern Chile. Two months of broadband seismic data col...
Article
Full-text available
The future response of the Antarctic ice sheet to rising temperatures remains highly uncertain. A useful period for assessing the sensitivity of Antarctica to warming is the Last Interglacial (LIG) (129 to 116 ky), which experienced warmer polar temperatures and higher global mean sea level (GMSL) (+6 to 9 m) relative to present day. LIG sea level...
Article
Full-text available
Glaciers in the dry Chilean Andes provide important ecological services, yet their mass balance response to past and ongoing climate change has been little studied. This study examines the recent (2002–2015), historical (1955–2005), and past (<1900) mass balance history of the high-altitude Guanaco Glacier (29.34°S, >5000 m), using a combination of...
Article
Full-text available
A full understanding of glacier changes in the Patagonian Andes over decadal to century timescales is presently limited by a lack of detailed and appropriate long-term observations. Here, we present geodetic mass and area changes of three valley glaciers from Monte San Lorenzo derived from stereo aerial photos, the Shuttle Radar Topography Mission...
Data
This is the second version of a bathymetric map of the Baker-Martinez fjord system (Chile, 48°S) constructed from multiple datasets: multibeam echosounder data of Baker channel (Harada et al., 2008) and of Steffen fjord and Baker river delta (Vandekerkhove et al., in press), single beam echosounder data of Martinez channel (R/V Sur-Austral 2015/201...
Preprint
Glacially- and magmatically-derived seismic events have been noted to heavily overlap in characteristics, thus there exists the potential for false-alarms or missed warnings at ice-covered volcanoes. Here we present the first study to specifically target icequakes at an ice-covered volcano in Southern Chile. Two months of broadband seismic data col...
Article
Full-text available
The Southern Patagonia Icefield (SPI) withdrawal in recent decades shows contrasting behaviours between adjacent basins. One of the basins with highest volumetric losses is located at northern- most SPI. We refer to Jorge Montt tidewater glacier (48° 30′S/73° 30′W, 445 km2 in 2018), which retreated 2.7 km between 2011 and 2018 and thinned at rates...
Article
Full-text available
The Northern and Southern Patagonian Icefields are the largest ice masses in the Southern Hemisphere outside Antarctica, but their ice volume and bed topography are poorly known. Here, we combine airborne gravity data collected in 2012 and 2016, with radar data from the Warm Ice Experiment Sounder and Centro de Estudios Cient´ıficos’s to map bed el...
Article
Full-text available
Glaciers on active volcanoes are subject to changes in both climate fluctuations and volcanic activity. Whereas many studies analysed changes on individual volcanoes, this study presents for the first time a comparison of glacier changes on active volcanoes on a continental scale. Glacier areas were mapped for 59 volcanoes across Latin America arou...
Article
Full-text available
Over 400 lakes exist beneath the Antarctic ice sheet. They range from giant stable lakes at the centre of the ice sheet, isolated from the atmosphere for millions of years, to small through-flow pockets of water beneath fast-flowing ice streams. Subglacial lakes likely harbour unique micro-organisms, adapted to the extreme conditions such as pressu...
Article
The Antarctic ice sheet is predicted to be the major contributor to sea-level rise during the XXI century. Therefore, monitoring ice dynamics of outlet glaciers in Antarctica is of great importance to assess future sea-level rise predictions. Union Glacier is one of the major outlet glaciers of the Ellsworth Mountains and drains into the Ronne-Filc...
Article
Full-text available
Since the Antarctic summer of 2014, the Chilean Center for Scientific Studies (CECs, for the Spanish acronym) has conducted four long-distance expeditions to the central plateau of West Antarctica for the purpose of studying the stability of the icecap and the subglacial hydrology. These ventures have been carried out using convoys pulled by tracto...
Article
Full-text available
The glaciers of Patagonia are the largest in South America and are shrinking rapidly, raising concerns about their contribution to sea‐level‐rise in the face of ongoing climatic change. However, modelling studies forecasting future glacier recession are limited by the scarcity of measured on‐glacier air temperatures, and thus tend to use spatially...
Preprint
The future response of the Antarctic ice sheets to rising temperatures remains highly uncertain. A valuable analogue for assessing the sensitivity of Antarctica to warming is the Last Interglacial (129-116 kyr), when global sea level peaked 6 to 9 meters above present. Here we report a blue-ice record of ice-sheet and environmental change from the...
Poster
Full-text available
The Antarctic ice sheet is predicted to be the major contributor to sea-level rise during the XXI century. Therefore, monitoring ice dynamics of outlet glaciers in Antarctica is of great importance to assess future sea-level rise predictions. Union Glacier is one of the major outlet glaciers of the Ellsworth Mountains and drains into the Ronne-Filc...
Conference Paper
Full-text available
It has been widely recognized that glaciers in Patagonia are shrinking rapidly and hence concern exists about the sea level rise contribution of these glaciers due to recent climate change and projected regional warming. To investigate the response of the glaciers to climate change, mass balance models depend on an accurate spatial representation o...
Presentation
The Last Interglacial (130 to 116 thousand years ago) is widely considered to have been warmer than today, but the timing and contribution of Antarctica to global sea level rise during this period remains uncertain. Here we report a new highly-resolved blue ice record close to the West Antarctic Ice Sheet grounding line that implies high-latitude o...
Article
Full-text available
In this study, we assessed the feasibility of using optical flow, in particular, large displacement optical flow (LDOF) method as a possible solution to obtain surface movement data to derive ice flow velocities in a glacier. Tests were carried out at the Viedma Glacier, located at the South Patagonia Icefield, Argentina, where terrestrial monoscop...
Data
The map is available here in 3 different formats: https://doi.org/10.6084/m9.figshare.5285521.v3 We present a bathymetric map of the Baker-Martinez fjord complex (Chile, 48⁰S) constructed from multiple data sets: multibeam echosounder data of Baker channel (Harada et al., 2008) and of Steffen fjord and Baker river delta (Vandekerkhove & Bertrand,...
Conference Paper
Full-text available
In the South Patagonia Icefield (SPI), glaciers are currently shrinking in response to mid-tropospheric warming. These glaciers are mainly sensitive to temperature change because ablation is dominated by melt. However, orographic effects can play an important role in ablation even for different glaciers at the same latitude. This is particularly th...
Article
Full-text available
Glacier melt is an important source of water for high Andean rivers in central Chile, especially in dry years, when it can be an important contributor to flows during late summer and autumn. However, few studies have quantified glacier melt contribution to streamflow in this region. To address this shortcoming, we present an analysis of meteorologi...
Article
Mass balance of a glacier is an accepted measure of how much mass a glacier gains or loses. In theory, it is typically computed by integral functional and empirically, it is approximated by arithmetic mean. However, the variability of such an approach was not studied satisfactory yet. In this paper we provide a dynamical system of mass balance meas...
Article
Full-text available
Reconstructing the dynamic response of the Antarctic ice sheets to warming during the Last Glacial Termination (LGT; 18,000–11,650 yrs ago) allows us to disentangle ice-climate feedbacks that are key to improving future projections. Whilst the sequence of events during this period is reasonably well-known, relatively poor chronological control has...
Article
This article reports the discovery of the subglacial Lake CECs (named in honor of the Centro de Estudios Científicos), located in the central part of the West Antarctic Ice Sheet (WAIS), on the ice divide between the Minnesota Glacier and the Institute Ice Stream. This lake, which was discovered by means of an oversnow traverse in January 2014 usin...
Article
Full-text available
We describe a novel method of heavy tails estimation based on transformed score (t-score). Based on a new score moment method we derive the t-Hill estimator, which estimates the extreme value index of a distribution function with regularly varying tail. t-Hill estimator is distribution sensitive, thus it differs in e.g. Pareto and log-gamma case. H...
Article
Se reporta el descubrimiento del Lago Subglacial CECs (en honor al nombre de la institución, Centro de Estudios Científicos), ubicado en la parte central del casquete de hielo de la Antártica Occidental (WAIS, por sus siglas en inglés), en la divisoria entre el Glaciar Minnesota y la Corriente de Hielo Institute. Este lago, que fue descubierto medi...
Article
We show how a dynamical system given by a t-score function for some class of monotonic data transformations generates consistent extreme value estimators. The variation of their values increases the uncertainty of proper assessment of climate change. Two important examples illustrate the methodology: mass balance measurements on Guanaco glacier, Ch...
Article
Full-text available
Glacier melt is an important source of water for Andean rivers in central Chile, especially in dry years when it can be the main contributor to lowland flows in late summer and autumn. However, few studies have quantified the glacier melt contribution to river runoff. To address some of these shortcomings, we present an analysis of meteorological c...
Article
Full-text available
In contrast to the general trend for glaciers of the Southern Patagonia Icefield, Glaciar Pio XI has experienced a large cumulative frontal advance since 1945. In an effort to better understand this advancing behaviour, this paper presents a synoptic analysis of frontal fluctuations (1998–2014), ice velocities (1986–2014), ice-surface elevations (1...
Article
Full-text available
In this work, we assessed the feasibility of using optical flow to obtain the motion estimation of a glacier. In general, former investigations used to detect glacier changes involve solutions that require repeated observations which are many times based on extensive field work. Taking into account glaciers are usually located in geographically com...
Article
Full-text available
In this work, we assessed the feasibility of using optical flow to obtain the motion estimation of a glacier. In general, former investigations used to detect glacier changes involve solutions that require repeated observations which are many times based on extensive field work. Taking into account glaciers are usually located in geographically com...
Conference Paper
During the last deglaciation (21,000 to 7,000years ago) global sea level rise was punctuated by several abrupt meltwater spikes triggered by the retreat of ice sheets and glaciers worldwide. However, the debate regarding the relative timing, geographical source and the physical mechanisms driving these rapid increases in sea level has catalyzed deb...