Конкурс за професор по Професионално направление Науки за земята

In the present report a new hybrid method about the natural hazards risk and multi-risk assessment is presented. Most popular European and world practices for risk assessment are incorporated. The main topic of the report is to present a new developed hybrid method for risk assessment for natural hazard which incorporates most useful applications and practices of several developed and applied useful practices – the IADB and ISDR methodology, the ESPON project classifications and the risk profiles calculations.

The new developed and adapted methodology is applied to several areas using real data. The results obtained can be very useful for the practice.

99.Ranguelov B., R.Jelinek, M.Wood., J Hervas., 2007, Risk mapping of Earthquakes in New Member States – JRC Sci.&Tech.Report, EUR 22901EN., 35 pp

A reprint reporting the achievements of the new member states in EU to the risk mapping of earthquakes. Special attention is paid to the definitions of hazards, vulnerability and risk and their relationships. Examples of the practices in different countries are selected.

Two stochastic models were applied to study the aftershock energy release after the Denali Fault earthquake of November 3, 2002 with a main shock magnitude Mw=7.9. We utilized the restricted epidemic type aftershock sequence (RETAS) model to analyze aftershock rate decay. According to it only events stronger than some triggering magnitude Mth can induce secondary shocks. We verified different variants of the RETAS model ranging from the limit case Mth = Mmain (main shock) to the case when Mth=Mo (lower magnitude cut-off). In the former case all aftershocks are considered to be generated by the main shock (modified Omori formula MOF) and in the latter each event can trigger secondary shocks (ETAS model). The results for the Denali Fault sequence reveal the best fit model to be RETAS with a triggering threshold Mth =3.2. We then exploited the obtained model of aftershock intensity to develop a model of the released Benioff energy of aftershocks under the assumptions that events’ magnitudes are independent of their times and among themselves. To do this we put in use an analog of a counting process for marked point processes. If events follow a Poisson process in time and each event can be associated to a realization of a random variable, then the mark-accululator stochastic process is said to be a compound Poisson process. The necessary requirements are that marks form a family of independent and identically distributed random variables and they are independent of time, too. We suggest these conditions apply to model aftershocks Benioff energy release for our data.. The modified Omori formula is used to model aftershock decay in time and released energy is the corresponding mark. The results reveal that Benioff energy release deviates (overpasses) from the compound process model at the beginning of the aftershock sequence – a

fact that is rarely considered in stochastic modeling of aftershock occurrence.
61.Ranguelov, B., S. Tinti, G. Pagnoni, R. Tonini, F. Zaniboni, and A. Armigliato (2008), The nonseismic tsunami observed in the Bulgarian Black Sea on May, 7th 2007. Was it due to a submarine landslide?, Geophys. Res. Lett., vol.35, L18613doi:10.1029/2008GL034905. IF-3.0

A tsunami-like sea disturbance of nonseismic origin was observed on 7 May 2007 on the Bulgarian Black Sea coast. The maximum wave amplitude was three meters, and the sea oscillations lasted for several hours. The anomalous behaviour was seen in many places of the coast of Bulgaria

and was stronger in the north. Several accounts of eyewitnesses as well as reports of local port authorities and three tide-gauge recordings are available and have been collected and analysed. The tsunami could have been produced by a submarine landslide or by atmospheric pressure pulses. Here, we explore the former hypothesis, .e., the possibility that the tsunami was induced by a landslide that may have occurred on the shelf margin off Bulgaria. By making use of numerical modelling we find that submarine mass movements taking place within a certain delimited source area off Bulgaria may have generated tsunamis compatible with the observations.
101.Ranguelov B., E.Mircheva, I.Lazarenko., R. Encheva., 2008. The archaeological site – possible evidence about multihazard ancient events, Proc. Conf. Geoarchaeology and Archaelomineralogy., 347-352 pp.

The paper deals with the Cybele ancient temple discovered near Balchik, 2007 and the possible natural disasters (may be) finishing its life in the ancient world. This is the most preserved monument belonging to these ancient times, dedicated to the Mother of Gods – Cybele. The hypothesis of the multidisaster natural events occurred consequently is presented using both – archaeological and geophysical evidences – Earthquakes, tsunamis and landslides as acting geodynamic forces, which caused the temple destruction and preservation. Most of the observations and discovered artifacts are interpreted as possible proofs about such of consequences of these tragic events destroyed the temple.

The paper deals with the new born discipline – archaeoseismology and its possible applications and development in Bulgaria. The rich archaeological environment of Bulgaria proved strongly during the last years is a general fact, which is considered there. On another side – the fast and effective development in Seismology provides equipment and infrastructure which could be useful for such combinative interdisciplinary approach together with the results of archaeology. Some effective examples due to the cooperation between the specialists of both disciplines are exposed and enlithed. The future development of this symbiosis is expected.

На основание на сеизмичната опасност картографирана в Европейско-Средиземноморската карта е предложена стратегия за о;енка на застрахователни полизи за различните района на България. Предложен е селективен подход от страна на застрахонателните компании в зависимост от реалната заматръсна опасност.

На основание на статистически изсладвания от поредици сеизмични последователни събития е показано, че апроксимациите на функциите апроксимиращи тези разпрадалания ( по време и разстояние) имат различни параметри. Това може да се талкува като характеристичен белег за формлно разделяне на сеизмичата активност по място на проявление в зависимост от конкретните геодинамични условия.

Изследвания на цунами включващи каталогизация, моделиране и дистанционни методи са прилагани през последните години. Низини, остри заливи, лагуни, лимани, речни делти и естуари – целият спектър от природни уязвими за цунами елементи са представени по Северното Българско Черноморие. В зависимост от пространственото си разположение и размера си , тези елементи са локални дадености увеличаващи негативните ефекти в резултатн на усилващото си влияние върху цунами нахлуванията. Статистическа оценка на уязвимостта на тези природни структури е предложена на основата на техните размери и пространствено разположение. Подобен подход е използуван и при оценка на уязвимостта на антропогенни конструкции. Модерни подходи (като цифров модел на релефа, измервания с ГПС, сателитни изображения и др.) са използувани за оценка на функциите на уязвимост за различните елементи. Предварителни класификации и типология е направена с цел разделяне на различните уязвими елементи от въздействията на цунами – по височина на вълната и скоростите й. Изследваната област е разположена между град Варна и румънската граница.

About 5400 BC, the Neolithic people started to produce salt to meet their needs, at a place called now Provadia-Solnitsata. A large salt body rediscovered recently in 1917 served as a source of this prehistoric factory that produced the most valuable item in prehistory – the salt, the most important and vital product of the early farmers. This unique site in Europe excavated by the archaeologists (excavations started 2005 and continue up to now) shows the history of this place. Huge industry for this prehistoric period was developed and functioned more then 1000 years. Thick walled pots and hearths for the brine evaporation have intensively been produced, and can be seen now. After the rediscovery of the salt body, new and more sophisticated techniques of salt production (the biggest raw material source for the nearby huge industry unit) have been applied in mid 1950s. It is possible to consider the prehistoric earthquake that occurred about 7,000 years ago and destroyed the Chalcolithic dry-stone fortifications as a natural hazard interrupting for some time the salt production. A lot of facts, evidences and a hypothesis about such an event are presented to support this conjecture.

В популярна форма е представено значението на Егейската сеизмогенна зона за обяснение на сеизмичната активност в района. Като повод е послужило конкретно земетресение в района на Македония (Валандово). Модерните методи за обработка на данните приложени главно от гръцки специалисти дават възможност да доста експресен анализ на възникналата геодинамична обстановка.

The results of the EU Project SCHEMA are presented. The new established facts and models about tsunami influence to the coast are discussed. The selection of Balchik area as a test site supports the scientific interest to this specific dangerous place on the NE Bulgarian Black Sea coast.

The classifications and aerospace methods about natural hazards studies are presented. The efectivenes of the space methods in a remote sensing methodology is assessed. New data and classifications about the dangerous natural hazards are discussed.

The most ancient salt production factory in Europe and the oldest seismic event documented to the region of Provadia are discussed. In the light of the new discovered artifacts and destruction in a very ancient settlement and its defensive walls a hypothesis about seismic influence is presented.

The cartography of weak seismicity in central west Bulgaria is based on the registered by NOTSSY during the ten years time window (1997-2000). The spatial and time distributions of the weak earthquakes are investigated in relation with the local listric faulting. This methodology is a pilot project which can be applied about other seismic zones as well.

Описани са сеизмологичните условия в района на археологическите разкопки на обект Провадия-Солницата. За първи път е доказано наличието на възможни разрушения от земетресение датирано към 4450 г. преди Христа. Това представлява първото в Европа документирано събитие с основни параметри по място и време в древната история на Европа.

Abstract: The paper examines the possibility that tsunami event recorded in the western Black

Sea on 7 May 2007 was triggered by a travelling atmospheric disturbance. As meteotsunamis are favoured by specific synoptic conditions, we inspected available ground and sounding observations, European Centre for Medium‐Range Weather Forecasts reanalysis fields, and satellite‐based products and compared them to the documented Mediterranean meteotsunamis. We found an atmospheric disturbance travelling toward 30° (NNE) with amplitude of 2–3 hPa and propagation speed of about 16 m/s, passing through few tens of kilometres 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. An

ocean modelling study showed that such a disturbance is capable of generating 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.

This Atlas is a collection of tsunami-wave-risk maps along the Northern Bulgarian Black Sea coast, Balchik site. These maps are the result of research work performed by a broad international scientific consortium using unified methods. This research work was performed in accordance with the work programme of a scientific research project under the 6th EU FP, entitled SCenarios for Hazard induced Emergencies MAnagement (SCHEMA). The entire project is aimed at dedicated studying of tsunami hazard and risk, using the most advanced technologies for the purpose (satellite images, complex non-linear methods, detailed elevation and bathymetric data and the like).

The main steps in composing the enclosed maps include:

● scenario definition;

● numerical modelling of tsunami generation and propagation;

● analysis of tsunami vulnerability and risk.

In scenario definition, data and information about previous tsunami waves in the

1. 
   Black Sea were used, which had negative effects on the coast. These include:
   

● available paleo-tsunami deposits;

● effects on the coast, settlements, and/or surface or sub-surface facilities.

In numerical modelling, the following were used:

● surface or sub-surface elevation maps to various scales and satellite images;

● tsunami sources (here, only seismic sources were taken into account);

● theoretical models accounting for wave propagation and wave-cost interaction

(the major part of this work was performed by the National Observatory of Athens).

In analyzing vulnerability and risk, the following were used:

● vulnerability and damage classification, derived mostly from field observations

(tsunami impact in the Indian Ocean on 26 December 2004);

● inundation distance of tsunami waves;

● propagation time of tsunami waves travel times of tsunami waves from their

source to various coastal points;

● model registrations on some virtual tide gauges;

● satellite images of buildings and facilities of various types.

The presented maps are thematic and may be divided into two basic types: regional

(comprising the coastal area between the Town of Varna and the Romanian frontier);

local (covering only the coastal area of the Town of Balchik).

The maps are of the following types:

● maps of the arrival time from the source to the coast;

● maps of the maximal water inundation;

● maps of the maximal water withdrawal into the sea;

● maps of the velocity of the water turbulences generated during water movement;

● maps of the vulnerability for the Town of Balchik;

● maps of the tsunami risk for the Town of Balchik.

At the end of the Atlas, some applications are provided, facilitating the understanding and use of the obtained results. These results are ONLY approximate and might benefit end users, such as the Civil Protection Service, local administrations, research institutions, companies and more. All activities under the SCHEMA Project were performed through the close collaboration of the teams from the project participating institutions.
50.Ranguelov B., G. Alexiev, D. Gospodinov, St. Scheer ., 2010. Natural hazards and preventive measures in Bulgaria., in “Bulgaria and Bulgarians in Europe”., (Еd. P. Petkov), “Faber”, V.Turnovo, pp. 385-393. ISBN 978-954-400-301-4

Описани са обобщените характеристики на основните природни бедствия заплашващи територията на страната, както и възможните превантивни мерки които биха намалили значително пораженията от тях. Това представлява първо обобщение от този характер в Европа.

A stochastic prediction of an earthquake occurrence (as well as any other attempt of seismic event prognosis) requires the determination of five elements: two co-ordinates, depth, magnitude and time. It is well known also that predicting the time is the crucial factor for the lack of success in earthquake prediction. The larger the magnitude, the territory and time span of the investigation are the more likely is that the results will be closer to the reality.

Southeast Australia is the first region on the continent with a documented history of earthquakes occurrence. But even here, only 130 years of written documenting is available, and this is a short term as far as seismological prediction is concern. The instrumentally recorded data are even more limited. The magnitudes of the intraplate events in this region are on the moderate size of the Richter scale. All these factors are imposing a number of limitations on earthquake prognosis, which may be one of the main reasons for nearly complete lack of studies on this subject. The mapping is a strong tool to this approach.
109.Ranguelov B. ., 2010. NONLINEARITIES AND FRACTAL PROPERTIES OF THE EUROPEAN-MEDITERRANEAN SEISMOTECTONIC MODEL., GEODYNAMICS & TECTONOPHYSICS., Vol. 1. № 3. pp. 225–230. ISSN 2078-502X.

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. [2001].

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.
111.Ranguelov B. 2010. THE SEISMOGENIC POTENTIAL OF THE SUBDUCTION ZONES – THE TWO GREAT EARTHQUAKES: CHILE (Mw8.8, 2010) AND SUMATRA (Mw9.1, 2004) – INDICATORS ABOUT SUDDEN PLATE MOVEMENTS. Ann. of M&G University, Vol. 53, Part I, Geology and Geophysics., p. 201-206. ISSN 1312-1820

ABSTRACT. Направен е сравнителен анализ между две от най-силните земетресения регистрирани напоследък на Земята и разположени в близост до конвергентните граници на плочите: Индийската и Сунда (в района на о-в Суматра) и Южноамериканската и Наска (по крайбрежието на Чили). В светлината на съвременната геодинамика, положението на епицентрите и хипоцентрите им, процесите на разкъсване на земната кора и други данни е потърсено обяснение на относително бързите движения на континенталните плочи или части от тях. Първото грандиозно земетресение (Мw9.1, 2004) генерира огромни вълни цунами, които погубиха над 200 000 души в много страни около Индийския океан, явявайки се по този начин едно от най-катастрофалните събития сполетели човечеството през цялата му история. Второто гигантско земетресения (Мw8.8, 2010) разположено в близост до Чилийското крайбрежие, генерира относително малки вълни цунами (явление абсолютно необичайно за подобни по сила земетресения), но предизвика тежки разрушения и повече от 1000 жертви в крайбрежните селища. За определянето на сеизмогенния потенциал на субдукционните зони да генерират много силни земетресения е от съществена важност да се оценят ограниченията лимитиращи геодинамичната активност на подводните земетръсни огнища. Огромни площи и обеми от континенталната разрушена земна кора са очертани от поредица силни следтрусове, които помагат за определянето на размерите им. GPS измервания, показват размерите на преместванията, регистрирани в околностите на тези силни земетресения.
112.Ranguelov B., 2010. The comparative analysis about the strong earthquakes near Sumatra (2004) and Chile (2010) tsunamigenic potential and geodesy displacements. Proc. INT. SYMP. MODERN TECHNOLOGIES, EDUCATION AND PROFESSIONAL PRACTICE IN GEODESY AND RELATED FIELDS, 23–24 Sept., Varna, Albena Resort., pp. 23-32. ISBN 978-80-87159-16-3.

The comparative analysis about the two strong earthquakes near continental plate boundaries – Indian and Sunda plates (Sumatra Island-Indonesia) and South America and Nazca plates (Chile coast) is made concerning their seismogenic and tsunamigenic potential. In the frame of the recent geotectonics, epicenter and hypocenter positions, depths of the seismic events, rupture process and the other parameters considered the explanation about the tsunami generation process is outlined. To know why two similar in power events generated (or did not generate) huge tsunamis, appears of essential importance in view of the people protection and economic safety of the threaten territories. The geodesy data and limitations due to the underwater sources of the earthquakes are considered.