Analysis of the Geological Controls and Kinematics of the Chgega Landslide (Mateur, Tunisia) Exploiting Photogrammetry and InSAR Technologies

Exploration of territories not previously analyzed by landslide experts provides interesting findings. The Chgega landslide, in northern Tunisia, represents a paradigmatic mass movement. It can be classified as a complex landslide, or more specifically as vast rock spreading that evolved into a block slide. It involves a great block of limestone—about 900 m long and 400 m wide—sliding over ductile clays and marls. The viscoplastic creep of the clays drives the landslide and creates, in its crown, a graben ~800 m long and ~120 m wide that breaks the summit of Chgega Mountain. Using Interferometric Synthetic Aperture Radar (InSAR) technologies, we demonstrate that this complex landslide is currently active and moreover shows progressive movement without clear episodic accelerations. The velocity of the limestone block is just above 2 mm/yr. The occurrence of gravity-induced joints indicates that the movement has an orientation towards 333° of azimuth on average, conditioned by the landscape around Chgega. These results were obtained through the analysis of a 3D model and a high-resolution orthoimage created from photographs acquired by an Uncrewed Aerial Vehicle (UAV). We may conclude that the landslide movement is determined by normal faults with directions N060°E and N140–150°E. This characterization of the Chgega landslide can serve as the basis for future studies about the origin of this slope movement. Furthermore, the data provided here may support the recognition of Chgega as a singular geological point that deserves to be declared a geosite.

Mind the Gap: Investigating Toddlers’ Sensitivity to Contact Relations in Predictive Events

Toddlers readily learn predictive relations between events (e.g., that event A predicts event B). However, they intervene on A to try to cause B only in a few contexts: When a dispositional agent initiates the event or when the event is described with causal language. The current studies look at whether toddlers’ failures are due merely to the difficulty of initiating interventions or to more general constraints on the kinds of events they represent as causal. Toddlers saw a block slide towards a base, but an occluder prevented them from seeing whether the block contacted the base; after the block disappeared behind the occluder, a toy connected to the base did or did not activate. We hypothesized that if toddlers construed the events as causal, they would be sensitive to the contact relations between the participants in the predictive event. In Experiment 1, the block either moved spontaneously (no dispositional agent) or emerged already in motion (a dispositional agent was potentially present). Toddlers were sensitive to the contact relations only when a dispositional agent was potentially present. Experiment 2 confirmed that toddlers inferred a hidden agent was present when the block emerged in motion. In Experiment 3, the block moved spontaneously, but the events were described either with non-causal (‘‘here’s my block’’) or causal (‘‘the block can make it go’’) language. Toddlers were sensitive to the contact relations only when given causal language. These findings suggest that dispositional agency and causal language facilitate toddlers’ ability to represent causal relationships.

Alternative method of analysis of results of 3D terrestrial laser scanning (comment to the article “Contribution to a rock block slide examination by a model of mutual transformation of point clouds”, Acta Carsologica 38,1)

The article Konic et al. (2009) describes efforts to find out if the rock block on which the castle of Črni kal is situated slid away from the Kraški rob wall. 3D terrestrial laser scanning has been used to determine positions of many points on both presumed contact surfaces and 12-parameter affine transformation that transforms the cloud of points from one wall into another has been found. The deviation between matching point clouds has been used as a test of the original hypothesis. It has been concluded that the rock block did slide. Some of the data from the article are re-analysed using another numerical method. A 6-parameter translation composed with rotation that best transforms the 12 published points from the rock block wall into their counterparts on the Kraški rob wall is found. The original hypothesis is confirmed and some additional insight into the block slide is revealed.Keywords: rock block slide, 12-parameter affine transformation, rotation matrix, translation vector.

Design of the Automatic Position Block for the Punched Holes on Angle Steel of Transmission Tower

It is proposed that the design and operation process of the automatic position block for the holes punching used for the angle steel of transmission tower structure. It consists of position block, slide block, screw, nut, motor, and controller. If the anchor points have been set, the hole punching position can be anchored automatically, and setting the anchor points are easy operated. It can equipped in punching press, and improve greatly the current hole punching process.