An assessment of the landslide risk (Rls) for the territory of Bulgaria by administrative districts has been made by combining the vulnerability (V) and landslide hazard (Hls) maps. Landslides are a significant part of geological hazards and are widespread throughout the country. In order to assess the landslide risk for the territory of Bulgaria, it is necessary to take into account not only all landslides for a given region, but also its vulnerability, and thus to assess the level of landslide risk for this region, Rls = f (V, Hls). Landslide risk is determined by a risk matrix, using selected indicators and weighting coefficient of vulnerability and landslide hazard. Assessing the vulnerability of a region subjected to geological hazards is a key component of risk assessment. These include the exposure of infrastructure, industrial facilities and production capacity, residential buildings, regional GDP per capita and potential for human disability (defined by population density in the district). The data used is combined to create a map showing the vulnerability of each administrative district. Indicators of population density, GDP, length of road and railway networks and number of residential buildings were used to assess the vulnerability. The landslide hazard in each administrative district is determined by the intensity of landslide processes in the district, depending on the level of their activity and the affected area. The normalized (distributed) hazard of landslides for an administrative region is given depending on the area of the given administrative region. Landslides are categorized as active, potential and stabilized. The results express the weighted average hazard. Landslide hazard is rated from 1 to 5, where 1 means no landslide hazard and 5 means that landslide hazard has a very high intensity (very high hazard). The high degree of landslide hazard in turn leads to possible economic losses, social and environmental consequences (landslide risk). The intensity (level) of landslide vulnerability, hazard and risk is assessed as very low, low, medium, high and very high, and is shown on the relevant maps.

The article presents the results of the landslide mapping in the area of the town of Polski Trambesh, central Northern Bulgaria. A total of 37 new landslides have been described, which have not been included in the landslide register so far. Landslides are classified by area, type and activity. Their location is mapped in a GIS environment.

Risk assessment methodology is described in detail and applied for assessing the geological hazard for potential landslides and earthquakes. This methodology follows the guidelines of ISO 31010 and the JRC recommendations, and is applied for the first time in Bulgaria. The obtained results have high practical applicability. The flexibility of the methodology allows the final result to be presented as either a risk matrix or risk profiles. It depends on the specific tasks, issues and scientific problems that need to be solved.

In October 2019, a 3D extensometer was installed to monitor slow landslide movements, affecting the slope of Cape Emine north of the lighthouse. For almost 2 years of observations, a tendency of shrinkage of the zone as a result of lateral pressure from the southern landslide was established. The movements are divided into two stages: the first – until December 2020, and the second – after that date. In the months from April to June the movements in direction X are more intensive due to the rainy situation at this time of the year.

This paper presents methodology for geological risk and multy-risk assessment. It is fully in accordance with IEC 31010:2019 and JRC recommendations and has been already applied in the practice. The methodology demonstrating flexibility, adaptability and sustainability within a set of all geological hazards. It is successfully applied to the complex risk assessment of Primorsko municipality.