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This is a short review of fractal analysis applications in Bulgaria to investigate the geodynamics at the local, regional, and global levels.

The report presents an early warning system against earthquakes of the conceptual design of the tunnels under the “Shipka” Pass. Bulgaria gives many victims on the roads - those killed in traffic crashes and accidents. In the case of tunnel facilities in seismic areas, chain accidents in tunnel pipes are particularly dangerous. Early warning systems for tunnels make it possible to immediately stop traffic by the traffic police or automatically, to include additional ventilation equipment and turn on the additional reserve lighting installations.

Natural geophysical fields are a valuable source of information about the surface and deeper layers of the Earth’s crust, representing the most geodynamically active part of the geophysical section. In these depths (including the upper mantle and the asthenosphere) the effects of all endogenous processes and their consequences on the earth’s crust are manifested – block fragmentation, fault network, active geodynamic processes (earthquakes, volcanoes, displacements of the earth’s surface, etc.). With proper interpretation, the presence or absence of cross-correlation and relationships between different fields can serve as heuristic estimates of various geodynamic parameters, which in turn are useful in the practice of studying the geodynamics of Turkey., XI National Geophysical Conference, 9th June 2023

Археосеизмологията е нова дисциплина за България, която се развива през последните десетилетия. Нейна основна цел е изучаването на земетръсни ефекти върху археологически обекти – паметници, сгради и съоръжения, църкви и обредни храмове, крепости и др., както и на селища, древни градове и села, пристанищни съоръжения и др. Като страна с богато археологическо наследство разположено в области попадали под въздействието на локални и регионални сеизмични източници, може да се очаква, че запазени сеизмични ефекти ще бъдат открити от специалистите-археосеизмолози. Предлаганият обзор се занимава с наблюдаване сеизмични ефекти върху единични или многопланови археологични обекти. Много нова информация е получена в резултат на съвместните Българо-Руски полеви експедиции проведени с висококласни специалисти от Русия и България. Те разкриват нови и неочаквани данни за древни земетресения и позволяват определянето на основни техни параметри – време на реализация, сила, и с по-малка точност – местоположение на сеизмичния източник. Като се комбинира информацията от множество дисциплини от науките за Земята – археология, геодинамика, неотектоника и сеизмология се получават данни, които могат да послужат за нова оценка на сеизмичната опасност в страната., X National Geophysical Conference, 4th June 2021, p. 60-67

Considering that coastal hazards are trans-boundary in nature, the underlying objective of CABARET Project (CApacity Building in Asia for Resilience EducaTion) is to foster regional cooperation for more effective multi-hazard early warning (MHEW) as a mitigation measure and to increase disaster resilience among coastal communities., peer-reviewed

Batangas is a first-class province of the Philippines located on the southwestern part of Luzon in the CALABARZON region. Its capital is Batangas City and it is bordered by the provinces of Cavite and Laguna to the north and Quezon to the east. Across the Verde Island Passages to the south is the island of Mindoro and to the west lies the South China Sea. Geographically, Batangas is a combination an elevation of 600 meters, located in the middle of the Taal Lake. Other important peaks in Batangas include Mt. Makulot with an elevation of 830 m, Mt. Talamitan with 700 m, Mt. Pico de Loro with 664 m, Mt. Batulao with 811 m, Mt. Manabo with 830 m, and Mt. Daguldol with 672 m. The province has many beaches and is famous for its excellent diving spots. It has the second largest international seaport in the Philippines after Metro Manila. The identification of the city as an industrial growth center in the region and being the focal point of the CALABARZON program resulted in the increasing number of business nature of the province and its current development, the present study was envisioned to assess its preparation for any forms of an imminent natural disaster. In particular, the study assessed the usage of multi-hazard early warning systems in the province using survey interviews with various stakeholders. The results of the 30 survey interviews showed that there are a limited multi-hazard early warning systems in the province despite the fact that the majority of the participants have experienced natural disasters in their respective areas., peer-reviewed

CABARET (Capacity Building in Asia for Resilience EducaTion) is a co-funded by an EU Erasmus+ programme project run for three years and led by the University of Huddersfield’s Global Disaster Resilience Centre, based in the UK. They are joined by a group of experts from a consortium of 14 European and Asian higher education institutions from Bulgaria, Indonesia, Latvia, the Maldives, Malta, Myanmar, the Philippines, Spain, Sri Lanka, and the United Kingdom. The Intergovernmental Oceanographic Commission of UNESCO (IOC-UNESCO), the Asian Disaster Preparedness Centre and the Federation of Sri Lankan Local Government Authorities are Associate Partners helping to promote the benefits across Asia and beyond. http://cabaret.buildresilience.org/images/CABARET_flyer.pdf CABARET emphasises the role of Higher Education in supporting global priorities and targets on disaster risk reduction. The project provides capacity development to support regional cooperation on multi-hazard early warning systems (MHEWS) in coastal communities, with a particular focus on Asia. The paper deals with the main tasks of the project, their execution and outcomes and benefits after it finished., peer-reviewed

The temporal decay of eight aftershock sequences in the area of Greece after 1975 was examined with main shocks magnitudes of Mw ≥ 6.6. The analysis was done through the restricted epidemic type aftershock sequence (RETAS) stochastic model, which enables the possibility to recognize the prevailing clustering pattern of the relaxation process in the examined areas. In four of the cases the analysis selected the epidemic type aftershock sequence (ETAS) model to offer the most appropriate depiction of the aftershock temporal distribution which presumes that all shocks to the smallest ones in the sample can cause secondary aftershocks, while for the rest of the sequences triggering potential seems to have aftershocks above a certain magnitude threshold (RETAS model) and they are expected to induce secondary activity. The models, developed on aftershock data, were also applied to forecast real seismicity after the conclusion of the aftershock sequences. For four out of eight cases, we obtained promising estimations of ensuing seismicity after the end of the sequences with models based only on aftershock data. Some features of the RETAS model simulation were also studied, like simulating magnitudes, revealing that it is reasonable to consider in the model the temporal behavior of the aftershocks’ magnitudes as well. Stochastic modeling was also applied to estimate the duration of the relaxation process, assuming that the end of each sequence is marked by the divergence of real seismicity from the modified Omori formula (MOF) model, the latter known to represent pure aftershock activity. The obtained results give an indication that possibly low stressing rate results in longer duration of the relaxation process in a region. © 2007 Elsevier B.V. All rights reserved.

This paper presents research results of the study which aim is to reveal and quantitatively describe fractal properties of the European-Mediterranean seismotectonic model applied for seismic hazard assessment of the region under study. Several seismotectonic provinces are defined, and their nonlinear properties are calculated using both linear elements (boundaries of seismogenic units) and surface areas of the seismogenic units. The research is conducted on the basis of only formal relationships, not with data on real fault structures or other seismogenic elements, as the relationships have been accepted for seismic hazard calculations by the team of SESAME Project (Project Leader M. Jimenec) and published by Jimenec et al. [2007]. Special attention is paid to the Balkan seismotectonic model in order to develop a common seismotectonic model which uses data from the seismic hazard map for a period of 475 years (according the EUROCODE8), that was published in Muco et al. [2008]. All the calculations considered only the seismogenic units located in the earth crust, but not deeper seismogenic layers. It is concluded that most of the seismogenic provinces are similar in their fractal properties, which varied in a narrow range, except for the Adriatic one. The formal approach does not permit to explain these peculiarities.

We examined a possibility that tsunami event recorded in the western Black Sea on 7 May 2007 was triggered by a traveling atmospheric disturbance. Maximum tsunami wave heights of 3 m were observed in a number of places, although no earthquake occurred in the region at that day. Therefore, two options for the source remained: (i) submarine landslide at the Black Sea slope (Ranguelov et al., Geophysical Research Letters, 2008, showed that such an process is capable to produce the observed waves), or (ii) atmospheric high-frequency processes. As meteotsunamis are favoring specific synoptic conditions, we inspected available ground and sounding observations, ECMWF reanalysis fields and satellite-based products and compared them to the documented Mediterranean meteotsunamis. We found the atmospheric disturbance traveling towards NNE with amplitude of 2-3 hPa and propagation speed of about 16 m/s, passing through few tens of kilometers wide pathway over the region affected by the tsunami. This disturbance occurred in the lower troposphere, but it was capped by instable convective cell that preserved gravity disturbance’s coherence over a region at least 150 km long. Ocean modeling study showed that such a disturbance is capable to generate large tsunami waves and strong currents over the shallow regions, following the observations over the region where maximum sea level oscillations have been documented. Therefore, this event has a potential to be classified as a meteotsunami, the first of such kind in the Black Sea.