Giant Landslides Research Articles

Giant landslide, hidden caldera structure, magnetic anomalies and tectonics in southern Tyrrhenian Sea (Italy)

Phlegraean Fields and Ischia Island are large, densely populated, active volcanic structures located in the Campanian Tyrrhenian margin between the onshore and offshore sectors. While the emerged landforms provide significant insights into a series of intense volcano-tectonic events of the last 60 ka, our understanding of the sub-marine portion of these volcanoes remains limited due to its inaccessibility to direct exploration. In the last decades, the use of magnetic methods has proven to be useful in volcanic context, given the presence of large magnetization contrasts, whereas the implementation of a high-resolution Digital Elevation Model (DEM) has allowed the integration of detailed morphological analyses into the geophysical studies. In this work, we present two new high-resolution airborne and shipborne magnetic surveys, carried out by the National Institute of Geophysics and Volcanology (INGV) in the marine sector of the Phlegraean Fields caldera (Pozzuoli Bay) and surrounding sea sectors. Moreover, the new datasets have been integrated with older marine surveys carried out by the National Research Council (CNR) to extend the resulting magnetic anomaly map embracing the whole Campanian offshore volcanic structures, excluding Ischia Island. As a result, we present here three new magnetic anomaly maps used for an integrated interpretation of magnetic, morphological, and tectonic features. The study results provide valuable insights into the relationship between volcanic, magmatic, and tectonic activity, which may be useful for further investigations. Among the most notable findings are: the identification of the magnetic signatures of regional faults, previously unknown caldera structures, and a massive rock avalanche. Consequently, our research provides a significant contribution to seabed exploration aimed at identifying potential hazard factors in the study area.

Typical characteristics and causes of giant landslides in the upper reaches of the Yellow River, China

Typical characteristics and causes of giant landslides in the upper reaches of the Yellow River, China

Terrace formation linked to outburst floods at the Diexi palaeo-landslide dam, upper Minjiang River, eastern Tibetan Plateau

Abstract. River terraces are frequently investigated with the aim of extracting information regarding tectonic or climate forcing on the evolution of landscapes. Terraces formed following the blockage of valleys by large-scale landsliding have received limited attention despite the high likelihood of their prevalence in landslide-dominated mountain belts. Here, we investigate the geomorphology, sedimentology, and chronology of two outstanding sets of terraces upstream of the giant river-blocking Diexi palaeo-landslide on the upper Minjiang River, eastern Tibetan Plateau. The first set occurs at Tuanjie village and has seven levels (T1–T7); the second set, at Taiping village, has three levels (T1–T3). All the terraces display a consistent sedimentary sequence comprising lacustrine muds topped by fluvial gravel sometimes capped by loess and a palaeosol. Based on field examination, lithofacies analysis, elevation data, and chronometric data (optically stimulated luminescence and radiocarbon dating), we correlate T1, T2, and T3 at Taiping with T5, T6, and T7 at Tuanjie. Our analysis suggests that two damming and three outburst events have occurred at the Diexi palaeo-landslide over the past 35 000 years. A giant landslide (> 300 m high) blocked the river before 35 ka, followed by the first outburst flood at ∼ 27 ka; the river was blocked again between 27 and 17 ka, followed by a second outburst at ∼ 17 ka. A third outburst at ∼ 12 ka was followed by gradual fluvial incision of the palaeo-dam crest to its current level. We attribute the terraces at Diexi to the recurrent blockage and outburst events, which reflect the shifting sediment transport capacity and incision at the palaeo-dam crest. Here, climatic fluctuations play a minor role in terrace formation, and tectonism plays no role at all.

Study on Temporal and Spatial Distribution of Landslides in the Upper Reaches of the Yellow River

The geological structure of the upper reaches of the Yellow River is complex, especially in the Sigouxia-Laganxia section. It has always been a high-incidence area of landslide disasters, which poses a threat to the safe operation of the upper reaches of the Yellow River. In this study, based on the high-precision remote sensing image data, the spatial distribution of each landslide was obtained by superimposing the remote sensing image and the 1:50,000 digital elevation model (DEM). Some typical landslides were selected for detailed field investigation and field verification. The results show that the remote sensing image characteristics of landslides in the upper reaches of the Yellow River are obvious. Through remote sensing interpretation and field investigation, a total of 508 landslides of various types were found, including 24 giant landslides. The spatial spreading patterns of landslides mainly include six types: dumb-bell shape, rectangle, saddle type, long arc shape, triangle, and side-by-side shape. The length and width of the landslide deposit are mainly concentrated at 550–1500 m and 600–1500 m, and the average elevation of the sliding body is mainly concentrated between 2000 and 2800 m. The average slope of the landslide is mainly distributed between 15–20°. Giant landslides are mainly distributed in the Jianzha basin area, surrounded by the Jishishan fault and the Lajishan fault in the West Qinling Mountains. The spatial distribution characteristics of giant landslides have obvious regional differences due to different factors such as lithologic differences and riverside erosion. The research results are of great significance for the early identification, prevention, and mitigation of landslide disasters in the upper reaches of the Yellow River.

Sedimentary records of giant landslide-dam breach events in western Sichuan, China

Introduction: Landslide-dammed lake outburst floods (LLOFs) are common natural disasters in high-mountain regions, posing serious safety threats to residents’ livelihoods and properties and causing major damage to engineering facilities. Giant landslides and river damming events commonly occur in the Eastern Tibetan Plateau in southwestern China. Dam failure generate LLOFs that form outburst deposits (ODs). This phenomenon is particularly common in some giant ancient landslide-dammed lakes.Methods: This study conducted a detailed investigation of the sedimentary characteristics of large-scale landslide-dammed lake outburst deposits in the Diexi Reach of the Upper Minjiang River and Tangjiashan Reach of the Tongkou River Basin, West Sichuan Plateau, China. Meanwhile, typical evidence of high-energy ODs was recorded.Results and Discussion: The longitudinal distribution of these ODs is similar to an elongated fan-shaped terrace along the river channel, presenting a distinctive sedimentary disordered–sub-ordered–ordered sequence from upstream to downstream. Several typical units of “sedimentary facies” are developed in the OD profiles, such as boulder units deposited by high-energy outburst flood (OF) events and the gravel and sand units representing pulsating-flow sedimentary environments during the recession stage. The grain size frequency curves are bimodal, and the granularity accumulated curves are upward convex, which reflect that the detrital characteristics of the sediment source area are mainly composed of coarse gravel and boulders. This indicates that the coarse gravel sediment gradually become decreased from upstream to downstream. Moreover, the OD hydrodynamic intensity displays a gradual weakening, and sediment sorting is improved. From upstream to the downstream, the mean particle-size and sorting of the ODs gradually decrease. The skewness become larger, and the kurtosis of the ODs is distributed in all the types. In addition, the different combinations of quartz sand surface microtextures indicate the transformation from high-to low-energy impacts over a short distance, which is controlled by flood hydrodynamics and regime.Significance: These sedimentary characteristics of ODs explain the hydrodynamic changes during the propagation of OFs, and are also important records for distinguishing between ODs, and “normal” floods.

Mechanically Controlled Landslide Deformation

AbstractMany landslide models assume a fully deformable body without any resistance against deformation. However, in reality, landslide bodies can display negligible to large deformation during motion. Examples for limited deformation include the prehistoric giant landslides of Flims and Köfels, or the Vajont landslide of 1963, where the structure of rock largely remained intact and the slides did not evolve into rock avalanches. Here, we propose a novel mechanical model for the controlled deformation of landslides. The model is based on the principle of material strength or resistance and includes a user‐specified function that reflects the mechanisms (internal friction, cohesion, viscosity, and yield strength) that act against the deformation induced by the free‐surface or the hydraulic pressure gradient of the landslide. This controls the landslide deformation and, in turn, also the motion and run‐out, and offers a unique possibility to describe the landslide motion ranging from a fully non‐deformable body sliding along the mountain slope to a completely fluidized motion without any resistance against the force associated with the free‐surface pressure gradient. The latter is the situation often considered for the motion of granular flows such as avalanches of snow or rock, or debris flows. The former can play a substantial role in the dynamics, however, has not yet been considered in mass flow simulations, severely limiting the applicability of those models. We demonstrate the performance of the new model and its applicability, also with the advanced open‐source computational mass flow simulation tool r.avaflow.

Revisiting spatiotemporal evolution process and mechanism of a giant reservoir landslide during weather extremes

An updated comprehension of landslide kinematics is a prerequisite for developing effective risk assessment and emergency management in the context of climate variability and anthropogenic disturbances. This study employs a multidisciplinary approach, taking the Outang landslide in China's Three Gorges Reservoir area as a case study. We examined the spatiotemporal surface processes and time- and subzone-dependent hydrometeorological factors from 2007 to 2021, particularly identifying rainfall regimes and reservoir water levels that trigger landslide movements. Given the uneven distribution of GNSS surface markers, we introduced weighted monthly mean displacement (D) and weighted marker frequency (f), enhancing the accuracy of our insights into distinct active subzones of the landslide. Preliminary results revealed July, September and June as months of higher susceptibility, as well as months with low water levels. The early-stage deformation control by reservoir water levels is being increasingly overshadowed by rainfall, due to extreme weather events and localized anti-slip measures. Long-term surface processes have also highlighted the transformation of landslide failure modes towards a compound pattern, from a predominantly retrogressive to a thrust-dominated pattern, and even overall translation coupled with localized rotation. Furthermore, the comparative analysis of normalized displacement/strain demonstrates the power and potential of integrating multi-source monitoring data. By revisiting the evolution processes and potential deformation mechanisms of the Outang landslide, we are getting closer to understanding more about the dynamics of giant landslides in reservoir areas, and illuminate the pathway towards enhanced risk management and emergency response strategies.

Standing on the shoulder of a giant landslide: A six-year long InSAR look at a slow-moving hillslope in the western Karakoram

In this work, we investigate a slow-moving, large landslide (∼20 km2) in the Chitral district in Northern Pakistan, near several villages. The slow-moving landslide was reported more than four decades ago but has never been examined afterward. Interferometric Synthetic Aperture Radar (InSAR) analyses, using Sentinel-1 data that span a period of six years, allowed us to retrieve the spatio-temporal pattern of hillslope deformation. We combined both ascending and descending orbits to identify vertical and horizontal deformations. Our results showed that the crown is moving relatively fast in comparison to the nearby regions; 30 mm/year and 40 mm/year in downward and eastward directions, respectively. Also, step-like deformations observed over the crown reflect a deep-seated landslide. At the footslope, on the other hand, we captured relatively high deformations but in an upward direction; specifically 30 mm/year and 30 mm/year in upward and eastward directions, respectively. We have discussed the possible roles of meteorologic and anthropogenic factors causing hillslope deformation occurred during the six-year period under consideration. We observed a seasonal deformation patterns that might be mainly interpreted to be governed by the influence of snowmelt due to increasing temperatures during the start of spring. Overall, the same mechanism might be present in many other hillslopes across the whole Hindukush-Himalayan-Karakoram range, where seasonal snowmelt is an active agent. In this context, this research provides a case study shedding a light on the hillslope deformation mechanism at the western edge of the Himalayan range.

Characteristics and mechanisms of large-scale old landslides and landslide dams in the Loess Plateau—A case study from Daning County, Shanxi Province, China

Giant landslides and dammed lakes occurred frequently during the prehistoric period; however, their mechanisms often remain an open issue because they are complex. This study used field investigations to observe four old landslides and three landslide dams in Daning County, Shanxi Province, China. Remote sensing images captured during different periods were used to compare the landforms of landslides, landslide dams, and their surrounding environments in detail. Subsequently, their shapes, scales, spatial distributions, and positional relationships were determined. The ages of 14C obtained from the paleolandslide dam lake (PDL) deposits were 3742 ± 95, 4115 ± 121, 6544 ± 91, 7814 ± 109 cal a BP. The 14C ages of the deposits under the sliding surfaces of the old landslides were 2748 ± 27, 4470 ± 54, and 8245 ± 79 cal a BP. Based on the actual physical geographical conditions and geomorphological characteristics of the region, combined with the above age data, that the following conclusions were made: (i) During the Holocene, from 2700 to 8200 years ago, heavy rainfall was the main reason for the occurrence of landslides and landslide dams in the region. (ii) Under the condition of heavy rainfall, the slopes with angles >60° in the Loess Plateau are prone to form landslide masses, and the size of the landslide is related to rainfall intensity. A landslide dam was easily formed when the sliding direction was perpendicular to the direction of the valley. It is difficult to form landslide dams when the sliding direction is almost consistent with the downward direction of the valley. (iii) The formation mechanism of old landslides shows that collapse or sliding may occur suddenly in loess geological masses under an external rainfall scenario. Moreover, the process of landslide dams is related to the geomorphic forms of the original valley.

Formation and distribution of landslides controlled by thrust-strike-slip fault zones and fluvial erosion in the Western Qinling Mountains, China

In active orogenic belts, fault zones and fluvial erosion are the two principal factors that control the development of landslides. The Langma-Baiya fault zone (LBFZ) and the Bailongjiang fault zone (BFZ) in the Western Qinling Mountains (WQM) in China are part of an intracontinental orogenic zone, where landslides are the principal geomorphological process. It is also one of the regions with the most severe landslide disasters in China. We established a historical landslide database for the LBFZ and BFZ, based on high-precision remote sensing image interpretation and field investigation. The results indicated a total of 2764 landslides, including 1190 large landslides and 79 giant landslides. The quality of the landslide database was evaluated using the frequency-area curve distribution characteristics, and the results showed that the small-medium size landslides are underrepresented in the database, likely due to the influence of factors such as surface erosion, vegetation coverage, and human activities. Therefore, we focused on the spatial distribution and formation mechanism of large and giant landslides. Landslides are unevenly distributed in space; specifically, our field investigation and statistical analysis of swath profiles revealed that landslides are aggregated within tectonic zones, in areas of weak rock masses, and on the banks of rivers. Finally, based on the combination of the various factors controlling landslides, we divided the study area into three subregions, for which conceptual models were established. These models highlight the importance of the distance of the fault zone to a river, together with the degree of fluvial erosion, in controlling the development of landslides. The combined effects of fluvial erosion, geological structures, and the low-grade metamorphic rocks exposed along fault zones are major controls on the development of large landslides, and the local structural characteristics of thrust-strike-slip fault zones control the type of landslides.

Influence of Relative Sea-Level Rise, Meteoric Water Infiltration and Rock Weathering on Giant Volcanic Landslides

Recent studies have shown that giant landslides correlate with climatic variations. However, the precise processes involved in this phenomenon need to be better defined. This study investigates the causes of giant landslides using a modeling approach. Here, I show that the effect of meteoric water infiltration could be distinguished from that of the sea level rise in triggering paleo-landslides. It is possible to identify the cause of coastal paleo-landslides based on the age of occurrence and comparison with climatic signals when glacial maxima are wetter than during interglacial periods, as in Polynesia and East Equatorial Africa, but not in other cases (Caribbean, Indonesia). The role of pore-pressure variations and sea water loading variations is discussed. The interaction between the relative sea level rise, pre-existing relief and deep weak structure due to the presence of highly weathered lavas may trigger the conditions for a large landslide. Highly weathered lavas have very low friction angles in volcanic islands. When volcanoes are still active, pressure fluctuations in the magma chamber caused by sea level lowering are expected to play a significant role in the destabilization of the relief. Competing processes in real cases make it difficult to distinguish between these processes.

A new type of sliding zone soil and its severe effect on the formation of giant landslides in the Jinsha River tectonic suture zone, China

A new type of sliding zone soil and its severe effect on the formation of giant landslides in the Jinsha River tectonic suture zone, China

The upper Pleistocene (1.8–0.7 Ma) explosive eruptive history of Las Cañadas, ocean-island volcano, Tenerife

While most ocean-island volcanism is effusive, recent evidence has demonstrated that intraplate ocean island volcanoes can exhibit protracted explosive histories, with catastrophic eruption styles and hazardous behaviour more typically associated with volcanoes in continental and plate-margin settings. Tenerife is the largest explosive ocean-island volcano on Earth, with a prolonged (∼2 Ma) post-erosional history of caldera-forming, plinian and ignimbrite eruptions of evolved composition. The 0.7–1.8 Ma succession with 20 newly defined formations is reported for southern Tenerife, Canary Islands. In the last 2 Myr, the Las Cañadas volcano has produced >42 pumice-fall eruptions, 21 with extensive ignimbrites, and 12 inferred caldera collapse events. Pyroclastic density currents have repeatedly travelled more than15 km from source to the ocean, filling valleys and burying extensive interfluves. A robust whole-rock chemistry dataset, selected mineral chemistry, coupled with new 40Ar/39Ar ages of units through the pyroclastic stratigraphy, allow recognition of magmatic trends within the system on the order of 100 ky. The catastrophic explosive eruptions form three, 0.2–0.5 Myr-duration clusters (the Ucanca, Guajara and Diego-Hernandez) that do not appear to correspond simply with geochemical cycles, or to cycles of increasing eruption size or explosivity as has been previously proposed. During the clusters, large eruption frequencies averaged 1 every 20–45 kyrs. The eruption clusters were separated by hiatuses of ∼240–260 kyr, recorded by soils and unconformities, and may reflect marked changes in geographic dispersals following giant landslide breaches in Las Cañadas caldera wall. Two concurrent evolutionary magmatic trends are distinguished: one producing crystal-rich magmas, the other formed the cooler crystal-poor magmas: both spanned over a million years until 0.66 Ma, when the former ceased.

The largest rock avalanches in Patagonia: Timing and relation to Patagonian Ice Sheet retreat

One of the largest concentrations of giant landslides (≥108 m3) in Patagonia is in the eastern part of Lago Cochrane/Pueyrredón (LP) valley in Argentina. In addition to minor earthflows and rock slides, this landslide cluster is dominated by rock and debris avalanches that affect the northern slope of Meseta Belgrano, the largest of which have volumes >1 km3 and a runout of >10 km. To determine the chronology of these large landslides and their relationship to the geological setting and the glacial history related to the Last Glacial Maximum (LGM) ∼20–18 ka ago, we combined geomorphological mapping with absolute dating (luminescence and radiocarbon dating) and numerical modelling of slope stability. Dating and cross-cutting relationships with glaciolacustrine deposits suggest that some of the largest rock avalanches collapsed directly into a glacial lake between ∼17 and ∼12 ka, soon after deglaciation, but some were pre-glacial and landslide activity continued until today, posing a potential hazard to the area. In agreement with these data, numerical modelling suggests that slope stability was only marginally affected by ice retreat and glacial lake drainage, and landslides were most likely favoured by relatively low rock strength, related glacially-conditioned topography, and, possibly, seismic activity. A newly identified active fault at the base of the Meseta Belgrano, whose activity was likely enhanced by postglacial rebound, was probably the key factor that concentrated postglacial rock avalanches into the LP valley. We conclude that exceptionally large (km-scale) landslides can occur on slopes made of relatively weak rocks in a glacially-conditioned topographic setting even without a strong direct triggering effect of deglaciation, while fatigue due to long-term seismicity may promote collapse.

The Creep-Sliding Deformation Mechanism of the Jiaju Ancient Landslide in the Upstream of Dadu River, Tibetan Plateau, China

The Jiaju ancient landslide is a giant landslide located upstream of the Dadu River, eastern Tibetan Plateau, with a volume of approx. 7.04 × 108 m3. The Jiaju ancient landslide is complex and comprises five secondary sliding bodies, e.g., the Jiaju landslide (H01), Niexiaping landslide (H02), Xiaobawang landslide (H03), Niela landslide (H04), and Mt.-peak landslide (H05). Affected by regional neotectonic movement, heavy rainfall, river erosion, and lithology, the secondary sliding bodies of the Jiaju ancient landslide are undergoing significantly different creep-sliding deformation, which will cause great damage to villages, roads, and rivers around the sliding bodies. Combined with the SBAS-InSAR method, Sentinel-1A data from June 2018 to August 2021, remote sensing and field surveys, this study obtained the Jiaju ancient landslide deformation characteristics and deformation rate in the line-of-sight direction (VLOS), slope (VSlope), and vertical (VVertical). It is concluded that the maximum deformation rate of the Jiaju ancient landslide is significant. The maximum of VLOS, VSlope, and VVertical are −179 mm/a, −211 mm/a, and −67 mm/a, respectively. The Niela landslide (H04), Jiaju landslide (H01), and Mt.-peak landslide (H05) are very large and suffer strong deformation. Among these, the Niela landslide (H04) is in the accelerative deformation stage and at the Warn warning level, and the Jiaju landslide (H01) is in the creep deformation and attention warning level, especially heavy rainfall, which will accelerate landslide deformation and trigger reactivation. Because the geological structure is very complex for the Jiaju ancient landslide and strong neotectonic movement, under heavy rainfall, the secondary landslide creep-sliding rate of the Jiaju ancient landslide is easily accelerated and finally slides in part or as a whole, resulting in river blocking. It is suggested to strengthen the landslide deformation monitoring of the Niela landslide and Jiaju landslide and provide disaster mitigation and prevention support to the government and residents along the Dadu River watershed.

Large-scale submarine landslide drives long-lasting regime shift in slope sediment deposition

Abstract Submarine landslides and associated mass-transport deposits (MTDs) modify the physiography of continental margins and influence the evolution of submarine sediment routing systems. Previous studies highlighted the control of landslides and MTDs on subsequent sedimentary processes and deposits at spatial scales ranging from tens of centimeters to few kilometers, leaving a knowledge gap on how and for how long large-scale submarine landslides (i.e., headscarps wider than 50–100 km) may affect the stratigraphic evolution of continental margins. To fill this gap, we used three-dimensional seismic reflection data tied to an exploration well to investigate the impact of one of the largest submarine landslides discovered on Earth, the Mafia mega-slide (Mms) offshore Tanzania, on slope sediment deposition. Seismic data interpretation indicates that turbidite lobes/lobe complexes and coalescent mixed turbidite-contourite systems formed the pre-Mms stratigraphy between 38 and ca. 21 Ma (age of the Mms), whereas coarser-grained sheet turbidites and debrites accumulated after the Mms for ∼15 m.y., primarily on the topographic lows generated by the emplacement of the landslide. We interpret this drastic and long-lasting regime shift in sediment deposition to be driven by the increase in seafloor gradient and the capture and focus of feeding systems within the broad failed area. We propose that the extensive evacuation zones associated with such giant landslides can generate major “conveyor belts”, trapping land-derived material or sediments transported by along-slope processes such as bottom currents. During the progressive healing of the landslide escarpments, which may last for several million years, sand-prone facies are deposited primarily in the upper slope, filling up the accommodation space generated by the landslide, while deeper-water environments likely remain sediment starved or experience accumulation of finer-grained deposits. Our study provides new insights into the long-term response of slope depositional systems to large-scale submarine landslides, with implications for the transfer of coarse-grained sediments that can be applied to continental margins worldwide.

The Cumbre Nueva collapse (La Palma, Canary Islands): New age determinations and evidence of an isotopic excursion

Episodic giant landslides characterize the history of intraplate oceanic volcanic islands, disrupting the gradual accumulation of eruptive products during shield-building stages. On La Palma (Canary Islands), the giant Cumbre Nueva collapse, which ended volcanic activity at the Paleo-Cumbre Nueva rift, formed the 11 km wide “Caldera de Taburiente” collapse embayment. Lavas erupted before and after this collapse have been studied, and 40Ar/39Ar ages of groundmass separates from key flows are presented, particularly from the small post-collapse Bejenado volcano that grew within the collapse scar. The new data constrain the age of the Cumbre Nueva collapse to between 519 ± 20 ka and 529 ± 12 ka (2s) and confirm that it occurred during a period of rapid re-surfacing of the island. This study has also constrained the duration of activity of the post-collapse Bejenado volcano, and the results indicate that this was also brief (529 ± 12 ka to 491 ± 16 ka). Starting just before the time of the collapse, the radiogenic isotope compositions of the lavas shifted temporarily to more depleted compositions, perhaps indicating that an isotopically distinct magma source was being tapped. However, an isotopic excursion of similar magnitude also occurred later in the post-collapse activity, suggesting that the changes in isotope composition of the magma source continued after the collapse.

Timing of rapid cooling and erosional decay of two volcanic islands of the Canary Archipelago: implications from low-temperature thermochronology

The Canary Archipelago comprises seven volcanic islands formed by the activity of the Canary mantle anomaly that might have been caused by an ascending plume at the NW-African passive margin. The “Basal Complex (BC)”, which contains the islands pre-shield rock formations, is exposed in the northwest and central Fuerteventura and NW-La Gomera and preserves the archive of giant landslides that caused the removal of most of the shield-stage volcanic rocks. Tools, like low-temperature thermochronology (LTT) are sensitive to rapid cooling activities that accompany landslides. In addition, integrating LTT data with time–temperature (t–T) numerical modelling are a powerful tool for reconstructing the thermo-tectonic evolution as well as defining and quantifying long-term landscape evolution in a variety of geological settings. To unravel part of the long-term landscape evolution of Fuerteventura and La Gomera, zircon and apatite fission-track, and (U–Th)/He data combined with t–T numerical modelling were applied to 39 samples representing the main rock units of the BCs and younger magmatic rocks on both islands. In Fuerteventura, the Northwest and Central Basal Complexes reveal rapid cooling/exhumation of more than 200 °C at ~ 20 Ma. The quantification of the thickness of the rock column using the t–T cooling path would need the knowledge of the palaeo-heat flow. The published thickness of the moved rock column in Fuerteventura and La Gomera does not point to an extreme high heat flow. Therefore, the formation of a giant landslide leads to the removal of ~ 2.0 (± 0.5) km of the volcano rock column. Offshore, such a landslide has led to part of the Puerto Rosario large debris avalanche. The “Central Basal Complex” revealed two more rapid cooling/exhumation events at ~ 16 Ma and ~ 14 Ma that might also be related to landslides. The three landslides might be responsible for the formation of the nowadays Puerto Rosario Debris Avalanche Unit offshore. What might have caused the landslides in Fuerteventura. Age data published provide evidence for magmatic and tectonic activity that occur at the time of the formation of the giant landslides. In addition, the Miocene climate significant changes lead to changes in precipitation, and such changes might also provide a destabilisation of pyroclastic units. Therefore, the causes of the giant landslides might be related to more than only one process. The La Gomera BC has experienced two rapid cooling/exhumation events: the first at ~ 9 Ma, which might have caused ~ 2.0 (± 0.2) km of erosion forming the offshore Tazo avalanche, also known as the Tazo landslide. The second rapid cooling at ~ 8.0 Ma is located at the northwest of the Island and might have been caused by the Garajonay caldera collapse and followed by landslides. The landslides are assumed to have formed the Segments I, II, III, and VIII of the submarine debris avalanches offshore. Like Fuerteventura, both landslides might have been triggered by tectonic and magmatic activities as well as due to variation in precipitation caused by climate variation.

Remote Sensing Precursors Analysis for Giant Landslides

Monitoring and early warning systems for landslides are urgently needed worldwide to effectively reduce the losses of life and property caused by these natural disasters. Detecting the precursors of giant landslides constitutes the premise of landslide monitoring and early warning, and remote sensing is a powerful means to achieve this goal. In this work, we aim to summarize the basic types and evolutionary principles of giant landslide precursors, describe the remote sensing methods capable of identifying those precursors, and present typical cases of related sliding. Based on a review of the literature and an analysis of remote sensing imagery, the three main types of remote sensing techniques for capturing the geomorphological, geotechnical, and geoenvironmental precursors of giant landslides are optical, synthetic aperture radar (SAR), and thermal infrared methods, respectively. Time-series optical remote sensing data from medium-resolution satellites can be used to obtain abundant information on geomorphological changes, such as the extension of cracks and erosion ditches, and band algebraic analysis, image enhancement, and segmentation techniques are valuable for focusing on the locations of geomorphological landslide precursors. SAR sensors have the ability to monitor the slight slope deformation caused by unfavorable geological structures and can provide precursor information on imminent failure several days before a landslide; furthermore, persistent scatterer interferometric SAR has significant advantages in large-scale surface displacement monitoring. Thermal infrared imagery can identify landslide precursors by monitoring geoenvironmental information, especially in permafrost regions where glaciers are widely distributed; the reason may be that freeze–thaw cycles and snowmelt caused by increased temperatures affect the stability of the surface. Optical, SAR, and thermal remote sensing all exhibit unique advantages and play an essential role in the identification of giant landslide precursors. The combined application of these three remote sensing technologies to obtain the synthetic geomorphological, geotechnical, and geoenvironmental precursors of giant landslides would greatly promote the development of landslide early warning systems.

Blind identification of active landslides in urban areas: a new set of comprehensive criteria.

More than 70% of catastrophic landslides were previously unknown and brought tremendous losses to human life and property in urban regions; therefore, there is an urgent need for early identification of active landslides to eliminate landslide risk at the early stage. However, early identification of landslides has always been a worldwide challenge due to high concealment, steep topography, inaccessible location, and sudden onset. This work suggests a new set of comprehensive criteria for the early identification of landslides by integrating surface deformation, geological, topographic, geomorphological, and disaster-failure features. This set of criteria is universally applicable with no use of the prior knowledge of landslide locations (blind identification) and is successfully validated by a field survey. This work selects the Xuecheng region, a hard-hit area of landslides, as the study area and employs multisource data (seismic, geological, topographic, meteorological, SAR, and optical remote sensing data) and time-series InSAR technology to identify active landslides and reveal their deformation rules. Some new viewpoints are suggested. (1) The new comprehensive criteria synthesize the surface deformation, disaster-controlling, and disaster-inducing characteristics and achieve relatively high accuracy by field validation. (2) Forty-seven active landslides are identified in Xuecheng with no use of the prior knowledge of landslides. The soft rocks or soft-hard interbeddings, tectonic movement, fluvial undercutting and eroding, precipitation, earthquakes, and human engineering activity control or induce the development of these active landslides. (3) Two giant landslides that significantly threaten human lives and properties and exhibit different movement modes are selected to highlight the deformation rules of active landslides under the coupled action of poor lithologic condition, tectonic movement, river erosion, precipitation, and human engineering activity. The suggested new criteria can be applied to other landslide hard-hit urban regions and contribute to the timely and effective prevention and control of catastrophic landslides, reduction of enormous disaster losses, and rational management of the environment.