DETERMINISTIC SEISMIC HAZARD ANALYSIS OF THE CITY OF STRUMICA

Abstract

Seismic risk assessment is defined as the first and most significant step toward reducing potential losses from earthquakes as natural disasters, analyzed on local, urban, national, and continental level. This process includes validation and assessment of seismic hazard, which determines the expected level of ground motion that can be expected at a specific location. It is followed by the development of an exposure model containing a database of assets and people exposed to the hazard, and vulnerability assessment of the exposed elements conducted through the development and application of vulnerability functions that determine the probability of loss depending on the intensity of ground shaking. These three components of seismic risk enable the creation of relevant risk assessment analyses, leading to improved system preparedness before, during, and after emergency or crisis situations and/or disasters.
This study will analyze the first component of risk — seismic hazard. Through a deterministic seismic hazard assessment, the maximum level of ground motion expected within the territory of the city of Strumica will be determined as a pilot study within this research. The assessment will be based on selected, most credible past earthquake scenarios that have affected the city and its surrounding area. Following the history of neotectonics and seismicity in the territory of North Macedonia, the earthquake scenarios Pehcevo - Kresna (1904) with a magnitude of 7.2 and Valandovo - Dojran with a magnitude of 6.7, were selected as the most relevant past earthquake scenarios that had a significant impact on the analyzed area — the city of Strumica.
In order to visualize the obtained results, the two earthquake scenarios are simulated online using the open source software tool — OpenQuake Engine. The simulation is performed on the active fault source model ESHM20, developed as part of the European Database of Active Seismic Faults, with the obtained results appropriately illustrated for relevance analysis.
The process of seismic hazard assessment, as the first and most significant step in defining risk, through modeling past earthquake scenarios with the city of Strumica as a case study, can greatly assist researchers. This approach enables the simulation of potential outcomes, testing of strategies to mitigate earthquake impacts at a specific location, as well as updating existing and creating new emergency and disaster management plans, where the risk factor remains an essential component.