Original article: Estudio internacional de la U. de Chile reveló cómo el calor extremo agrieta los acantilados costeros
A study led by Ignacio Ibarra from the Faculty of Architecture and Urbanism at the University of Chile has demonstrated that temperature fluctuations can progressively weaken rocks and lead to landslides or rockfalls, even in the absence of rain or earthquakes.
This research, published in the Journal of Geophysical Research: Earth Surface, marks a pioneering effort in continuous monitoring of the surface temperatures of a coastal cliff over an entire year. Utilizing an infrared camera, the study gathered hourly data with a spatial resolution of 12 cm per pixel across an area exceeding 1,300 m2.
Using this data, more than 4,270 thermal images were processed through programming.
The study’s focus was a coastal cliff in Whitby, located in northeast England. The findings are surprising, even for this marine climate at mid-latitudes and close to current sea level: the rock experiences an extreme annual temperature range from -11.7 °C to 40.2 °C, representing a variation of nearly 52 °C.
Furthermore, the researchers identified 123 days with freezing and thawing cycles, processes known to progressively weaken rock structure. Abrupt temperature changes were also noted, with increases of up to 20 °C per hour and decreases of up to 13.7 °C per hour.
According to the research team, these conditions create thermal stresses that favor the formation and propagation of cracks, which can ultimately lead to rockfalls over time.
«An extreme event is not always necessary for a landslide to occur; thermal changes alone, even without snow cover, can be a determining factor,» says Professor Ibarra.
In this sense, one of the most significant findings of the study is that air temperature, often used in environmental analyses, does not accurately reflect what is happening on the rock surfaces. Direct measurements reveal that thermal variations in the ground are much more intense and dynamic than what traditional atmospheric records suggest.
The study also unveils that different factors govern rock temperature based on environmental conditions. On overcast days and in shaded conditions, the composition of the rock material is the primary thermal determinant. Conversely, on sunny days, the shape of the cliff and the incidence of solar radiation, including shading effects, play a predominant role.
For Ignacio Ibarra, these results contribute to a deeper understanding of slope instability, a crucial phenomenon in both natural and urban contexts: «Having high-resolution data over time and space opens new possibilities for anticipating threat and risk areas, as well as better understanding how these processes might evolve in climate change scenarios,» explained the University of Chile researcher.
This work also provides unprecedented empirical evidence and raises challenges regarding how these phenomena are studied, as until now, much of the thermal analysis on rocky slopes relied on short-term or low-resolution data, which could underestimate the real impact of thermal variations on slope stability and erosion.
Thus, with implications ranging from disaster risk management to land-use planning, this research offers significant insights to the scientific community, decision-makers, and policymakers concerning geomorphological processes and environmental change aimed at disaster prevention.
The findings are relevant not just for this cliff in the United Kingdom but also for considering coastal and Andean slopes in Chile, and how climate change may alter the frequency and intensity of these processes.
The Citizen
