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In the present study, we achieved the susceptibility mapping to slope instability processes by the implementation of Analytic Hierarchy Process and Weighted Linear Combination methods, in the North Branch of Argentino Lake, Southern Patagonian Icefield. The strong retraction of the glaciers in the area has triggered paraglacial readjustments, producing instability processes that favor the generation of mass removal processes. The results obtained from optical satellite images show that the highest degrees of susceptibility (4 and 5) are located on the western slopes of the Upsala Channel, Bertacchi and Cono Tributary Glaciers, and the Moyano and Norte Valleys, respectively. These slopes coincide with the geographic location of previous events surveyed by the inventory of unstable areas of the zone. Low degrees of susceptibility are found on the downhill valleys, outcrops rock and glaciers. The Consistency Ratio was 0.069, indicating that being less than 0.1 the study is reliable. The study sheds light on the knowledge of slopes and valleys that are more susceptible to processes of instability in mountainous areas, which would make it possible to prevent possible hazards associated with these events.

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Commission I, WG I/2 KEY WORDS: time-lapse, information extraction, ice-dam change, Perito Moreno ABSTRACT:This research provides a feasibility study on the implementation and performance assessment of time-lapse processing of a monoscopic image sequence, acquired by a calibrated camera in the Perito Moreno Glacier in Argentina. The glacier is located at 50° 28' 23''S, 73° 02' 10''W at the Parque Nacional Los Glaciares, South Patagonia Icefield, Santa Cruz and has experienced minor fluctuations and unusual behavior since the early 1960's to present. The objective of this study was to determine the evolution and changes in the ice-dam of the Perito Moreno glacier that started on November, 23 2012 and collapsed on January 19, 2013. Two images every 24 hours were acquired since October 2012 until February 2013, a total of 135 days. Image information was supported by ground data. Image and ground data was correlated with a 2D affine transformation. This technique allows the determination of the distortions in the images and estimating the values of scale factors. This, along with an accurate time-lapse interval, has produced accurate data for the analysis. In addition, changes in the level of the Brazo Rico lake were validated with direct data in order to determine the degree of uncertainty in the estimation of changes in the glacier. Based on the calculations, advance rates of the front of the Perito Moreno glacier were estimated at 0.67m/d ±0.003m, and the tunnel evolution was also recorded.

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We performed ground-penetrating radar measurements to study the internal structure of Puente del Inca (Inca Bridge). This natural structure is located in Mendoza, Argentina, and its formation is associated with deposition of travertine caused by geobiological processes created by hot mineral springs. The 200-MHz ground-penetrating radar measurements performed on the surface of the bridge allowed us to relate the behaviour of the electromagnetic signal with the presence or absence of hot spring activity. We also made ground-penetrating radar measurements at 20 MHz to estimate the propagation velocity and study the bridge's internal structure. In order to validate the groundpenetrating radar results, we used a soil dielectric sensor to obtain the attenuation and the velocity of the medium. The results showed similar propagation velocities (0.0222 m/ns on average) between field observation (ground-penetrating radar) and independent sensor data, as well as significant attenuation due to the hot spring water, which is the primary element controlling the response of the electromagnetic signals. As checked through dielectric sensor measurements, the unusually low electromagnetic wave velocity is due to polarisation mechanisms related to thermal water, which cause a very high permittivity value (178.1). However, the medium is not sufficiently dispersive (conductivity=27.7 mS/m; attenuation=3.5 dB/m) to condition the results of ground-penetrating radar measurements if low-frequency antennas (20 MHz) are used.

Ice surface temperature (IST) is one of the most relevant parameters when it comes to estimating the effects of climate change on glaciers. This study aims to estimate the IST for the Southern Patagonian Icefield (SPI) during the 2001–2016 period and, in so doing, to contribute to the assessment of the MOD11A1 product in this area. We evaluated IST performance by comparing it with that of automatic weather stations (AWSs). In addition, the glaciological significance of the results is presented through 1) IST trends, 2) annual IST anomalies, 3) IST behavior at different altitudes and orientations and 4) a comparison with Santa Cruz River flow records. The correlation coefficients obtained between the IST and AWSs ranged between 0.66 and 0.85. In addition, we report on the mean absolute differences between them, ranging between 0.6 ± 3.6°C and 9.4 ± 1.9°C. In this sense, we observed the lowest differences at the AWSs that were located in a homogeneous environment. Stated in glaciological terms: 1) only 1% of the pixels had a statically significant IST trend ( p-value ≤ 0.05): between 0.01 and 0.05°C/month; 2) we found that most of the IST anomalies ranged between –1 and 1°C throughout the period of this study; 3) the results suggest that the altimetric gradient was the most influential variable of the IST, mostly in north-oriented glaciers; and 4) the SPI IST showed an annual periodicity, which, in turn, shows a high correlation with the Santa Cruz River flow ( R = 0.86). This study is the first in estimating the SPI’s IST and contributes to enhance our knowledge of glacier dynamics and, therefore, the management of the water resource. Despite this, some MOD11 filtering is required in regions with high cloud cover frequency.