Use of two contemporary remote sensing technologies for mapping the Thracian Cliffs landslide (Northern Bulgarian Black Sea Coast)

In this paper are presented the results from the investigations of the active landslide, located in front of the Thracian Cliffs golf club (Northern Bulgarian Black Sea Coast) for the period 2019–2021. Extensive research by means of in-situ and remote sensing has been carried out on the latest landslide activations. As part of the study, a control GNSS geodynamic network was established. This network was used as benchmark for the results obtained from satellite SAR data processing and UAV surveys targeted at monitoring the modern landslide developments.

Comparison of the liquid limit of loess defined by the Vasiliev and Casagrande test methods

The paper compares liquid limit values obtained by the Vasiliev and Casagrande apparatus in line with BDS 648:1984 and BDS EN ISO/ TS 17892–12:2018, on the basis of testing 25 silty loess samples. The results indicated that compared with the Vasiliev apparatus, the Casagrande apparatus gives a higher liquid limit. An equation allowing conversion of the liquid limit obtained by the Vasiliev cone penetrometer to the liquid limit by the Casagrande apparatus has been developed.

General 1-D hydrogeological model for temporal near-surface loess saturation assessment for the needs of radon potential mapping

Radon gas has high mobility and is driven by advection and diffusion with the soil gas throughout connected and water-unsaturated pores and/or cracks in permeable rocks and soils. Hence the radon potential of the area could be dependent on not only geology as a constant source of radon but also from the changes of the saturation state of the ground. The loess complex, characterized by its permeability and usual state of unsaturation, covers 10% of the Bulgarian territory. The study deals with the principles of unsaturated domain modeling. An attempt of generic vertical infiltration model coinciding with the most upper part of loess vadose zone was performed.

Effect of the dewatering on the surrounding terrains during the construction of Metrostation 9-III of the Sofia Metropoliten

The international practice often faces significant settlements of terrains and structures due to dewatering. This study presents of the dewatering impact during the construction of Metrostation 9-III from the Sofia Metropoliten on the surrounding terrains and buildings. The subsidences are quantified for specific values of the soil deformation modulus and varying values of the soil hydraulic conductivity.

Traces of palaeoseismic activity in Lednika Cave, Western Rhodopes Mts, South Bulgaria

The caves are medium favorable for preservation of palaeoclimatic and palaeoseismic records. The deformed speleothems are accepted as a modern and useful tool for the prehistoric seismicity reconstruction. The aim of this short communication is to report the presence of deformed deposits in a newly discovered cave in South Bulgaria. Fallen, displaced and broken speleothems were found in the Lednika Cave. This 1287 m long cave is located near the Lepenitsa Cave, where such deformations are well described in the literature.

State of pollution of Ogosta River waters

The present research is related to one of the basic component of the environment – waters with study area the Ogosta river catchment. It is based on the investigation of water samples collected during field research in the river monitoring area and laboratory analysis. The research is focused on the state of the pollution and quality of the water. The results can be used in the processes of environmental optimization and realization of the strategies for sustainable development in the region.

Manganese pollution of drinking water extracted from the terrace of Vacha River

The presented study is aimed towards determining the reasons for manganese pollution of drinking water extracted from the terrace of Vacha River. The results show that this is due to the seepage of from the artificial lake, formed after the construction of a small hydropower plant. Another possible reason is the natural accumulation in the upper parts of the river terrace of poorly soluble in water manganese compounds that turn into soluble ones as a result of changes in the redox environment, which take place in the conditions of very intensive groundwater extraction.

Eclogite-like rocks from Southern Pirin Mountains – preliminary results about petrology and time of formation

North-northeast of the village of Ilinden (Southern Pirin Mnt.) three eclogite boudins were separated on the geological map in scale 1:50 000 (Sarov, 2010). The rocks belong to the Slasten lithotectonic unit. The mineral assemblage and mineral chemistry do not allow these rocks to be classified as eclogites. They can be considered as eclogite-like ones, formed by postmagmatic-metasomatic alteration of the host rocks. Based on LA-ICP-MS sphene U-Pb dating, eclogite-like rocks yield a Late Jurassic age (160±19 Ma).

Thermal behavior of Sr-form of gordaite

Cation-exchanged Sr-form of gordaite was successfully obtained from Ca-form of gordaite by an ion-exchange reaction. Data of XRD, SEM-EDS and DTA-TG-MS were used to characterize the Sr-form. Thermal decomposition of Sr-gordaite was studied for the first time in regards of thermal events and mass loss during volatile releasing. It was found similarity with Sr-gordaite and Ca-gordaite in terms of processes, type, and amount of volatiles released, but also some differences were found concerning the temperature correspondence of the volatiles evolving and the type of thermal decomposition products. The influence of the exchangeable cations (Na, Ca, or Sr) on the dehydration of the interlayer in the gordaite type structure were also established.

Klisura/Rozino granite, Central Sredna Gora: a part of the story of late Permian–Early Triassic extensional magmatic event

Тhe late- to post-Variscan magmatic activity in the South Black See region took plaсe during a considerably long period of ca. 80 from Late Carboniferous up to Early–Mid Triassic as two episodes are distinguished. The obtained age of 253.6±1.6 Ma for the Klisura/Rozino granite gives further evidence of the contemporaneous intrusive and extrusive magmatism during late Permian and Early Triassic in the Sredna Gora and Balkan zones.