Studying Seismic Events via Satellite Interferometry for the Territory

of the Balkan Peninsula

Mila Atanasova-Zlatareva

and Hristo Nikolov

Department of Geodesy, National Institute of Geophysics Geodesy and Geography,

Bulgarian Academy of Sciences, Sofia, Bulgaria

Remote Sensing Systems Department, Space Research and Technology Institute,

Bulgarian Academy of Sciences, Sofia, Bulgaria

Keywords: Co-Seismic Deformations, SAR Data, GNSS Networks, Balkan Peninsula.

Abstract: The prime focus of the current article is to present a pilot study in the project "Study of co-seismic

deformations of the Earth's crust for the territory of the Balkan Peninsula based on satellite data" that started

in December 2023. The purpose of the project is the regular monitoring of co-seismic deformations of the

Earth's crust using innovative methods for processing remotely sensed data. The main task is to demonstrate

the operational readiness to determine the magnitude of the deformations of the earth's surface, the size of

the affected areas and to prepare maps of the displacements that have occurred. This goal will be achieved

through the creation and realization of a methodology for extracting high-quality information from SAR

products aimed at continuous monitoring of areas that could be considered as potential foci of strong

earthquakes, integrating information from interferometric images and GNSS observations. As a result, a

working prototype of an information system for monitoring and prevention of the consequences of co-

seismic deformation of the earth's crust (landslides, collapses, etc.) based on freely available data provided

by ESA and national agencies will be created. The core of this system is an archive that will be created with

data from satellite SAR instruments for regions of the Balkans overlap in area and time registered

earthquakes with a magnitude above 5.0 for the period 2015-2025. The expected results are the created

deformation maps that, comparable to the position of the faults in the area and analysed with the tectonic

setting.

https://orcid.org/0000-0002-3105-3266

https://orcid.org/0000-0001-5764-1499

1 INTRODUCTION

Earthquakes are natural disasters that cause damage,

which is measured by human lives and destruction

of infrastructural objects and elements of the urban

environment. An important task after the occurrence

of such an event is the preparation of a plan for

overcoming them based on reliable scientific data

reveal the status of the affected territory.

Earthquakes most often occur at the boundaries of

tectonic plates, in zones of subduction. For the

region of Europe the strongest earthquakes occur

around the Hellenic arc and more rarely in the

interior of the Eurasian plate.

2 ANALYSIS OF THE CURRENT

STATE OF RESEARCH IN THE

INVESTIGATED AREA

2.1 Timeliness and Relevance of

Scientific Problems Addressed by

the Project

The Balkan Peninsula is one of the dangerous

seismic zones on Earth, where several seismic

events with a magnitude above 7 have occurred from

1900 up to now. Most of the seismic events were

generated near or in the fault zone known as the

Hellenic Arc located near the territory of Bulgaria

and earthquakes that occur on it are often felt. In the

152

Atanasova-Zlatareva, M. and Nikolov, H.

Studying Seismic Events via Satellite Interferometry for the Territory of the Balkan Peninsula.

DOI: 10.5220/0012689900003696

Paper published under CC license (CC BY-NC-ND 4.0)

In Proceedings of the 10th International Conference on Geographical Information Systems Theory, Applications and Management (GISTAM 2024), pages 152-159

ISBN: 978-989-758-694-1; ISSN: 2184-500X

past century, several destructive earthquakes with a

magnitude above 7.0 have been registered on the

territory of the country. Fortunately, they happened

at the beginning of the twentieth century, but these

events cannot be predicted and no territory is

immune from the possibility of this scenario

repeating itself (Solakov D. et al., 2018a.)

In this project we aim to investigate and

determine the deformation of the Earth's surface that

occurred in the Balkan Peninsula region after

earthquakes with a magnitude greater than 5.0 Mw

along the Mediterranean Seismic Zone that occurred

in the last 8 years (after 2015) recorded by NOA

(National Observatory of Athens) and USGS

(Geological Survey USA). The main task is to

demonstrate operational readiness to determine the

magnitude of deformations on the earth's surface, the

size of the affected area and to prepare maps of

displacements. Figure 1 shows the coverage of the

Mediterranean seismic zone with a fragment of the

map showing the risk of seismic activity in Europe.

Bulgaria has registered high seismic activity in

several areas. The most risky are: Kresnenska,

Plovdivska, Sofiiska, Gornooryakhovska and

Shablenska zones. The strongest earthquake had a

magnitude of 7.8 on the Richter scale and was

located in the valley of the Struma River in 1904.

The last strong earthquake was in the area of Pernik

on 22.05.2012 with a magnitude of 5.8 on the

Richter scale near Sofia and was felt by most of its

residents. The last stronger earthquake in Bulgaria

was in 2012 with a magnitude Mw of 5.6 near the

capital Sofia (Solakov D. et al., 2018b).

The last event that shook the whole world was the

earthquake doublet on February 6, 2023. in southern

Turkey near the northern border of Syria with

magnitude M 7.8, which was followed later by an

event with magnitude M 7.5 at about 90 km north of

the first. The location of the first earthquake is near

the triple junction of the Arabian and African plates

and the Anatolian block. In scientific community it is

widely accepted that seismicity in Turkey is due to

the relative movement of three large tectonic plates

(Arabian, Eurasian and African), as well as one

smaller tectonic block (Anatolian).

The geological development of the region is the

result of several boundary interactions between these

plates, which include subduction, large scale

faulting, compressional mountain uplift, and

extension of the Earth's crust. When the African and

Arabian plates converge the Eurasian plate leads to

the closure of the Mediterranean Sea and at the same

time is the reason for the westward movement of the

Anatolian block.

Figure 1: The Mediterranean Seismic Zone.

This movement is taking place mainly along the

fault lines on the two Anatolian fault lines –

Northern and Eastern. (Kalafat et al., 2021) The

westward movement of the Anatolian block is

mainly carried out by the North Anatolian fault

system evidenced by the large number of

earthquakes registered during the second half of the

last century. On the other hand, the same block

moves in a southwest direction towards the Arabian

Plate, as the movement is realized along the Eastern

Anatolian, where also earthquakes with magnitude

above 7 were recorded. Based on event from

27.01.2020 as well as other ones since the beginning

of the century it can be said that the Eastern

Anatolian fault is the more active (Utkucu M. et al.,

2023), (Reitman et al., 2023)

Co-seismic deformations of the Earth's crust

occur at the time of a strong seismic event, with a

magnitude above 5.0 on the Richter scale and have

manifestations on the Earth's surface at points near

to the epicentre of the event. They are determined

mainly by the satellite observations using

technologies based GNSS and SAR data, that was

applied successfully in the recent years.

The basic way to register and measure the

strength of an earthquake is through the use of a

seismic station, equipped with different types of

seismic receivers. In the last decade seismic stations

are supplemented by ground-based networks of

GNSS receivers, which provide the possibility to

determine displacements, occurring at the Earth's

surface and the propagation of seismic waves.

The Global Navigation Satellite System (GNSS)

is used to study the velocity field of the Earth's crust,

as well as Earth's deformations, attributed to

seismic, volcanic, geological or anthropogenic

activity. Using the GNSS method it is possible to

determine the 3D vector of displacement on the

earth's surface and calculate errors of 2–3 mm for

the horizontal and 5–8 mm respectively for the

Studying Seismic Events via Satellite Interferometry for the Territory of the Balkan Peninsula

153

vertical components confined to the position at the

point of measurement.

By processing data from Earth observation

satellites registering data with radar instruments by

DinSAR method provides greater spatial coverage,

but information about displacements is in the line-

of-sight (LoS) on the antenna. Additional analysis is

necessary to obtain all components of the Earth's

motion vector. The main sources of data that are

planned for use are the SAR products from the

Sentinel-1 mission thus achieving extensive

territorial coverage. This allows preparation of maps

that reveal the scale of deformations on the Earth's

surface. Along with these data other data for the

epicentre of earthquakes and for the established

faults in the research areas are used as well. Due to

the fact that the DInSAR method requires the

availability of two radar images obtained during a

time interval between the registrations of the SAR

data the mentioned maps reflect the cumulative

effect of all seismic events in this interval. This

means that it is not possible determine the

contribution of a single event to the produced

displacements.

2.2 Current State of the Research in

the Investigated Area

As mentioned, the Balkan Peninsula, and in

particular the territory of Bulgaria and Greece, show

active tectonics and seismicity. Currently advanced

space geodetic techniques and methods are used for

better understanding of long term geological and

geophysical processes. Based on the analysis and

processing of GNSS data, a number of studies show

the recent activity of the region and try to give a

reasonable and adequate interpretation of the

obtained results regarding the processes of

movement of the earth's crust in the region

(Burchfiel et al ., 2006), ( Burchfiel et. al., 2008),

(Georgiev et. al., 2013), (Kotzev et.al., 2006),

(Milev, Dabovski, 2006) (Matev, 2011), (Reilinger

and al., 2010), (Vassileva, Atanasova, 2014), (

Zagorchev, 2011) and others.

On July 20, 2017, an earthquake occurred near

the island of Kos with Mw 6.6 and a depth of 2 km.

The epicentre of the earthquake is located in the

Aegean Sea, about 1 km south of the uninhabited

island of Karaada and also the Greek islands of Kos

and town Bodrum with in the southwestern part of

Turkey was affected. Maps of the displacement were

created and the values of the southern time sinking

of Karaada Island in the LoS direction from

descending and ascending orbits were determined

(Atanasova § Nikolov 2018); (Atanasova § Nikolov

2019).

The surface deformations that occurred after an

earthquake on October 25, 2018 located about 45 km

southwest of the island of Zakynthos with Mw 6.8

and a depth of 10 km (Ganas et al., 2020) (Nikolov

et al., 2021) were also determined based on the

prepared interferograms. On November 26, 2019,

the most devastating earthquake in the last 40 years

for the region occurred in the north-western part of

Albania, which was the second such event in a

period of three months and was located about 8 km

northeast of the port city of Durres. The

interferometric results are presented in (Nikolov et

al., 2020) and (Nikolov et al., 2021).

The devastating earthquake that struck Croatia

on December 29, 2020 had a magnitude of 6.4 on

the Richter scale. This is the biggest earthquake in

Croatia recorded in the last century. An earthquake

of similar magnitude occurred in 1880 near Zagreb.

Three earthquakes of magnitude 6 and greater have

occurred since 1900 to date within 200 kilometres of

the epicentre of the said earthquake. The main shock

and most of the aftershocks are located on the

Petrinja Fault, which is well described in the

European Database of Seismogenic Faults (EDSF)

(Basili R et al., 2013). This phenomenon is

investigated by InSAR data and supplemented with

seismological results by using Okada method

(Dimova, Raykova 2023).

The surface deformations that occurred after an

earthquake of Mw 6.0, which occurred on March 3,

2021, 20 km northwest of Larissa, Greece were

determined. (see fig 2). Usually, using the applied

method, the total changes of the Earth’s crust are

registered for the period between two passes of the

satellites, which for the Sentinel mission (for 2021)

is a minimum of 6 days (Atanasova § Nikolov 2021)

(Atanasova et al., 2021). In the (Dimova, Raykova

2023) comparison of the results from pre-calculated

vertical (up–down) and horizontal (E–W)

displacements and the theoretical results obtained

from Okada`s model was made and good

coincidence for both of the suggested focal

echanisms for Larisa earthquake was found.

(Dimova, Raykova 2023) calculated three types of

geometry for the seismic fault near Larissa varying

the length, the width and the slip over the fault.

GISTAM 2024 - 10th International Conference on Geographical Information Systems Theory, Applications and Management

154

Descending orbits 80 orbit 02-14 March 2021

Ascendin

orbits 175 orbit 02-14 March 2021

Figure 2: Interferometric images of the area of the Larissa

earthquake and maps of the deformations along the LoS

direction determined by the two types of orbits.

The area covered by the displacements is quite

similar, although the Okada model underestimates a

little the values obtained by the DInSAR procedure.

It can be due to the uncertainties of the input

parameters used in the theoretical computation of the

displacement as well as the simplifications of the

Okada’s model.

The latest presented results obtained as a result

of the processing of SAR data, based on which

movements of the Earth’s surface caused by the

series of earthquakes that occurred in the border

region between Turkey and Syria were detected. The

latest challenge is to determine the deformations of

the wide areas, following the two devastating

earthquakes of magnitude M 7.8 and M 7.5 on

February 6, 2023. The earthquakes occurred in the

East Anatolian Fault Zone, west of Gaziantep,

Turkey.

The earthquake was followed by intense

aftershocks, the effect of which was proven after

interferometric processing of SAR data from the

European Space Agency's Sentinel-1 mission and

revealed the size of the affected area and the

magnitude of the deformations that occurred after

the earthquakes.

The maps created are combined data from

several sources: event epicenters from EMSC and

active faults from EDAF (Basili R.,, et al., 2013)

both considered to be the driving forces of ground

motions. SAR data, used to obtain information

indicating the actual surface displacements. It should

be emphasized that the mentioned information does

not reflect the consequences of one seismic event,

but the effect of all earthquakes that occurred in the

studied region between the dates of registration by

the SAR instrument (Atanasova et al., 2023),

(Nikolov & Atanasova, 2023).

Figure 3: Interferometric images of the area of the Turkey

earthquake registering the vertical deformations by

descending orbit SAR data, earthquake area and

epicentres, active faults.

3 OBJECTIVES AND

HYPOTHESES FOR

DEVELOPMENT OF THE

PROJECT

The purpose of this study is the regular monitoring

of seismic deformations of the Earth’s crust using

innovative methods. The main task is to demonstrate

operational readiness to determine the magnitude of

the deformations of the Earth’s surface, the size of

the affected areas and to prepare maps of the

displacements that have occurred. This goal will be

achieved through the creation and realization of a

methodology for extracting high-quality information

from SAR products aimed at continuous monitoring

Studying Seismic Events via Satellite Interferometry for the Territory of the Balkan Peninsula

155

of areas that could be considered as potential foci of

strong earthquakes, integrating interferometric

images (IFI) and GNSS data. As a result, a working

prototype of an information system for monitoring

and prevention of the consequences of co-seismic

deformation of the Earth’s crust (landslides,

collapses, etc.) based on freely available data

provided by ESA and national sources will be

created.

Achievement of the set goal is realized through

interrelated and complementary scientific and

scientific-applied tasks:

– Creation of a catalogue with earthquakes in the

Balkan Peninsula having magnitude of 5.0 or

more Mw

– Creation of automated methodology for

extraction of data from SAR and their unified

processing for geocoding.

– Obtaining the coordinates and speeds of the

permanent GNSS stations coordinates and

velocity of permanent GNSC stations from the

national network of NIGGG and freely available

data from other types of GNSS stations for the

territory of the Balkan Peninsula.

– Analysis of GNSS time series to register changes

(jumps) due to seismic events

– Determination of the deformations of the Earth’s

crust by the method of Okada on geophysical and

seismic data and their comparison with the

results obtained from the SAR data

– Formation of a data base for the investigated

areas , including IFI , geodetic data from

permanent stations, seismic and geophysical

data, as well as carrying out spatial analysis

regarding the presence of deformational

processes ;

– Determining the possibility of searching for a

connection between the location of the epicentre

of an earthquake and the tectonics of the research

area, lithospheric plates and the possibility of

predicting the occurrence of an event based on

changes in the magnetic field or other

geophysical factors.

After the implementation of the above

formulated tasks, it will be reached the fulfilment of

the second goal of presenting the information system

not only among the scientific community, but also

before the national and local authorities, the

academic community and other interested parties. In

this way we hope to give them the opportunity to use

a new tool to solve the problem before it occurs on a

specific disaster of natural or anthropogenic

character.

One of the scientific tasks envisaged to be solved

include the development of methodological

approaches for the comparison of the results of the

joint processing of interferometric images from the

SAR, the data from the permanent GNSS stations

and the obtained results for the deformations of the

Earth’s crust by Okada's method on geophysical and

seismic data.

After the primary processing of the three types of

data, their fusion and subsequent spatial analysis in a

GIS environment is foreseen. In this way, the degree

of preparedness of national and local authorities, as

well as society as a whole, will be increased, the

prevention will improve and the consequences of

this kind of disasters overcomed.

4 METHODS, RESEARCH

EQUIPMENT AND

TECHNIQUES

4.1 Global Navigation Satellite Systems

Global navigation satellite systems (GNSS) consist

of a ground network of receivers, space and control

segments. The use of GNSS for seismic monitoring

in Bulgaria and the Balkans has great potential,

using data from GNSS networks with free access

such as: international- ITRF, IGS; Regional - EPN

on EUREF; National GNSS network.

Registration of seismic movements of the Earth's

crust on the territory of Bulgaria on the basis of data

received from permanent GNSS networks can be

used for operational seismic monitoring and

supplementing information related to the occurrence

and tracking of events, thus delivering information

on the Earth's crust movements at Balkan Peninsula.

In the present project it is anticipated to use the data

from the National Geodetic Network, maintained by

NIGGG-BAS.

4.2 Bulgarian Seismological Network

NIGGG-BAS runs the Bulgarian seismological

network-NOTSSI (National Operative Telemetric

System for Seismological Information). NOTSSI

was founded at the end of 1980. The network

comprises today 17 permanent seismic stations and

two local networks. In 2005 the modernization of the

seismological network was performed. The overall

objective for the NOTSSI is continuous monitoring

of seismicity on the territory of Bulgaria and

adjacent areas within the Balkan region. After the

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156

modernization, NOTSSI became a world-class

digital network providing reliable, real-time seismic

monitoring and rapid earthquake information to both

scientific communities and authorities in Bulgaria

for seismic risk mitigation. Recently developed

Methodology for analysis, assessment and mapping

of the seismic risk of Bulgaria; and the new seismic

hazard assessment for Bulgaria are based on the high

quality seismological information.

Figure 4: The horizontal velocities of the points of the

Basic class of the State GPS network - 2014-

2018.

https://ngic.bg/.

The area subject to research in the proposed project

covers the Balkan Peninsula, which justifies the

need for additional GPS/GNSS infrastructure in it,

since successful monitoring of modern crustal

movements implies: permanent stations with

sufficient density and GNSS points.

4.3 Differential Interferometry

Differential interferometry (DinSAR) is a method

for processing radar data from synthesized aperture,

derived from remote Earth observation, that can be

used to quantify small displacements on the surface.

For example, using data from the Sentinel-1 satellite

and applying DInSAR, mapping of topography over

a large area or registration of movements on the

Earth's surface is performed. The DInSAR method is

based on using two images of the phase signal

backscattered from the Earth's surface obtained for

the same region at different times. In processing the

SAR data, co-registration of the two SAR images is

performed and then a differential interferogram is

generated, which shows the magnitude of the

deformation using the change in the phase signal.

The horizontal and vertical movements are

registered in LoS vector that needs to be

decomposed. At the stage of formation of the

interferogram a digital terrain model (DEM) with a

resolution of 1 arcsec is used, since it is essential

that the spatial resolution of the final interferometric

image (IFI) be as high as possible.

4.4 Okada's Method

The surface displacement, due to the elastic

deformations of the earth's crust, after generated

earthquake was obtained as an analytical solution of

Okada's formulas (Okada, 1985, 1992).

The co-seismic deformation is calculated as a

function of the geometrical parameters of the fault

and the elastic properties of the medium. The

geometry of the modelled faults was calculated

using the formulas of Mai and Beroza (2000) for the

relationship between the seismic moment of a given

earthquake and its magnitude.

4.5 GIS Data

Initially, a register will be created of all registered

earthquakes with a magnitude above 5.0 in the last

eight years (after 2015) for the Balkan region and

neighboring territories. This database will continue

to be populated throughout the duration of the

project. Based on it, the location and time interval of

the seismic event will be identified, which will make

it possible to proceed to the creation of the

specialized archive with SAR data.

Here, additional terrain elevation data will be

required, so DEM data must be available from

external sources, such as SRTM or ASTER

repositories, and must be included in the local

archive already created. After that, it is planned to

integrate the IFI and GNSS data from the

geodynamic network. Here, both data types must be

in the same coordinate reference system and

projection.

Based on this, we will prepare displacements maps

in GIS layers for the Balkan region in a time interval

of 6 or 12 days, based only on IFI, which will allow

us to obtain the movements that occurred during the

earthquakes.

5 CONCLUSIONS

The purpose of the project is formulated on the basis

of previous scientific and scientific applied research

on the team. The implementation of the project will

help to increase the quantity and quality of

fundamental scientific research related to problems

Studying Seismic Events via Satellite Interferometry for the Territory of the Balkan Peninsula

157

of regional and national importance. The tasks of the

project include both the intensification of the

relationship between science and education and

society as a whole and the enhancement of the

quantity and quality of the internationally visible

scientific output.

The public challenges to which the project is

focused are minimizing the damages from natural

disasters and accidents and for protecting the

environment. The project also responds to them by

studying geodynamic processes in the Earth's crust

and providing up-to-date information about them.

ACKNOWLEDGEMENTS

This study was supported by the Contract № KP-06-

N74/2 from 14.12.2023, (project “Study of co-

seismic deformations of the earth's crust for the

territory of the Balkan Peninsula based on satellite

data” financed by Competition for financial support

of basic research projects – 2023.

The authors would like to express their gratitude

to European Space Agency for providing Sentinel-1

SAR data and processing software SNAP at no cost.

REFERENCES

Atanasova M., Nikolov H., Protopopova V., (2018)

Determining the deformations of the earth's crust after

an earthquake using DInSAR. IX National Conference

on Geophysics - CD, 2018, ISSN:1314-2518 (in

Bulgarian)

Atanasova M., Nikolov H., Protopopova V., (2019).

DInSAR in displacement detection after seismic

events. Proceeding 10th Congress of Balkan

Geophysical Society, 18-22 September 2019, Albena

Resort, Bulgaria, EAGE, 2019, DOI: 10.3997/2214-

4609.201902642, 1-4. SJR (Scopus):0.11

Atanasova Mila, Nikolov H., (2021) Determining the

deformations of the earth's crust using DInSAR that

occurred after the earthquake in the Larisa region of

March 3, 2021. 10TH NATIONAL CONFERENCE ON

GEOPHYSICS / National Institute of Geophysics,

Geodesy and Geography, BA Sofia, CD 10, X, Society

of Geophysicists in Bulgaria, 2021, ISSN:1314-2518,

1-8, (in Bulgarian) https://www.niggg-bas.com/

periodicals/x-national-geophysical-conference-4th-

june-2021/n3/

Atanasova Mila, Nikolov Hristo, (2022) A STUDY OF

SEISMIC DISPLACEMENTS IN THE BALKANS

FROM SATELLITE DATA, Proceeding XXX

International symposium on modern technologies,

education and professional practice in geodesy and

related fields, Sofia, 02 – 04 November 2022

ISSN:2367-6051, 1-11

Atanasova M., Nikolov H., Oynakov E. (2021) Co-

Seismic Surface Displacements After The Earthquakes

In Larissa, 3 March 2021, Derived By Dinsar.

Proceedings of 21th International Multidisciplinary

Scientific GeoConference SGEM 2021, Volume: 21,

Book number: 2.1, International Multidisciplinary

Scientific Geoconference, 2021, ISBN:1314-2704,

ISSN:978-619-7603-22-4,

DOI:10.5593/sgem2021/2.1/s10.64, 521-528.

Atanasova M, Raykova P, Nikolov H., (2023)

Determining the Deformations of the Earth's Surface

after the Earthquakes in Turkey-Syria of 06 February

2023 - Initial Results. Comptes rendus de l’Académie

bulgare des Sciences, 76, 4, Bulgarian Academy of

Sciences, 2023, ISSN:1310–1331, DOI:https://doi.org/

10.7546/CRABS.2023.04.07, 554-562

Atanasova Mila. (2023) Determination of coseismic

deformations in the Balkan Peninsula area based on

SAR data. XI National Geophysical Conference, 9th

June 2023. Proceedings of the XI National

Geophysical Conference, 9th June 2023., XI, NIGGG-

BAS, CD, 2023, DOI: https://doi.org/10.48368/BGS-

2023.1.N12 (in Bulgarian)

Basili R., V. Kastelic, M. B. Demircioglu, D. Garcia

Moreno, E. S.Nemser et al. (2013) The European

Database of Seismogenic Faults (EDSF) compiled in

the framework of the Project SHARE,

https://doi.org/10.6092/INGV. IT-SHARE-EDSF.

Burchfiel, B.C., King, R.W., Todosov, A., Kotzev, V.,

Durmurdzanov, N., Serafimovski, T., Nurce, B. (2006)

GPS results for Macedonia and its importance for the

tectonics of the Southern Balkan extensional regime.

Tectonophysics, 413, 239-248

Burchfiel, B.C., Nakov, R., Dumurdzanov, N.,

Papanikolaou, D., Tzankov, T., Serafimovski, T.,

King, R.W., Kotzev, V., Todosov, A., Nurce, B.

(2008) Evolution and dynamics of the Cenozoic

tectonics of the South Balkan extensional system.

Geosphere, 4, 919-938, doi:10.1130/GES00169.1 1.

Copernicus. Sentinel-1 data 2017 to 2021. Retrieved from

ASF DAAC (8 Nov 2019), Processed by ESA.

Available online: https://asf.alaska.edu/ (accessed on

May 2021).

Dimova, L. R. Raykova. (2023) Complex analysis of

earthquake deformations using SAR images:

Examples from Croatia and Greece. Journal of

Physics: Conference Series (JPCS). 2668(1):012011,

DOI: 10.1088/1742-6596/2668/1/012011

Ganas, А., P. Briole, G. Bozionelos, A. Barberopoulou, P.

Elias, V. Tsironi, S. Valkaniotis, A. Moshou, I.

Mintourakis, (2020) The 25 October 2018 Mw = 6.7

Zakynthos earthquake (Ionian Sea, Greece): A low-

angle fault model based on GNSS data, relocated

seismicity, small tsunami and implications for the

seismic hazard in the west Hellenic Arc, Journal of

Geodynamics, 137, 2020

Georgiev, I., Dimitrov, D. and Botev, E. (2013) Crustal

Motion Monitoring in Bulgaria and Surrounding

GISTAM 2024 - 10th International Conference on Geographical Information Systems Theory, Applications and Management

158

Regions by Permanent GPS Array. Proceedings of 7th

Congress of Balkan Geophysical Society, Tirana,

Albania, 7-10 October 2013, 5

Kalafat D., A. C. Zülfikar and S. Okuyan Akcan (2021)

Seismicity of Turkey and Real-Time Seismology

Applications in Determining Earthquake Hazard,

Academic Platform Journal of Natural Hazards and

Disaster Management, vol. 2, no. 2, pp. 96-111, Dec.

2021, doi:10.52114/apjhad.1039670

Kotzev, V., Nakov, R., Georgiev, Tz., Burchfiel, B.C.,

King, R.W. (2006) Crustal motion and strain

accumulation in western Bulgaria. Tectonophysics,

413, 127-145.

Mai, P. M., Beroza, G. C., (2000), Source scaling

properties from finite-fault-rupture models, Bull.

Seismol. Soc. Am., 90, 3, 604-615.

Matev, K. (2011) GPS constrains on current tectonics of

southwest Bulgaria, northern Greece and Albania.

Thesis, Doctor of university of Grenoble, 203.

Milev, G. and Dabovski, C. (Eds) (2006) Geodynamics оf

the Balkan Peninsula, Monograph, Reports on

Geodesy. Warsaw University of Technology, Institute

of Geodesy and Geodetic Astronomy, 647.

Nikolov H., Atanasova M., Protopopova V.,(2021).

Application of satellite SAR data to detect

deformations of the Earth's crust after earthquakes.

Proceedings of 2nd National Workshop with

International Participation on COPERNICUS, S, pace

Research and Technology Institute - Bulgarian

Academy of Sciences (SRTI-BAS), Sofia, Bulgaria,

2021, DOI:10.5281/zenodo.6497513, 25-37

Nikolov H., Valentina P., Atanasova M.(2020) Studying

seismic events via satellite interferometry.

Proceedings Volume 11524, Eighth International

Conference on Remote Sensing and Geoinformation of

the Environment (RSCy2020); Paphos, Cyprus,

15241B, 11524, SPIE 2020, Proceedings of SPIE -

The International Society for Optical Engineering,

2020, 11524, 115241B, 2020, ISBN:978-151063857-

0, ISSN:0277786X, DOI:10.1117/12.2570676, 1-16.

Nikolov, H., & Atanasova, M. (2023). Co-seismic ground

motions from earthquakes in Turkey-Syria as

registered by SAR data. XI National Geophysical

Conference, 9th June 2023. https://doi.org/10.48368/

BGS-2023.1.N11 (in Bulgarian)

Okada, Y., 1985, Surface deformation due to shear and

tensile faults in a half-space, Bull. Seismol. Soc. Am.,

75, 4, 1135-1154.

Okada, Y., 1992, Internal deformation due to shear and

tensile faults in a half-space, Bull. Seismol. Soc. Am.,

82, 2, 1018-1040.

Solakov, DSimeonova. S., Raykova P., Aleksandrova I

(2018a). Empirical Relations Converting Md and Mp

Magnitudes Applied In Bulgarian Seismological

Routine Practice To Moment Magnitude. Comptes

rendus de l’Acad´emie bulgare des Sciences, 71, 8,

DOI:10.7546/CRABS.2018.08.09, 1076-1085

Solakov, D., Simeonova, S., Raykova, P., Aleksandrova, I

(2018b). Seismological analysis of the low frequencies

Mw5.6 earthquake in Sofia Seismogenic zone. Procc.

9th International INQUA Meeting on

Paleoseismology, Active Tectonics and

Archeoseismology, PATA, 267-270.

Reilinger, R., McClusky, S., Paradissis, D., Ergintav, S.

and Vernant, Ph.(2010) Geodetic constraints on the

tectonic evolution of the Aegean region and strain

accumulation along the Hellenic subduction zone.

Tectonophysics, 488, 22-30.

Reitman N, еt al., (2023) Preliminary fault rupture

mapping of the 2023 M7.8 and M7.5 Türkiye

Earthquakes. DOI: https://doi.org/10.5066/P985I7U2

Utkucu M. Et al., A preliminary report on the 2023

Gaziantep (Mw=7.7) and Elbistan (Mw=7.5),

earthquakes in Southeast Türkiye, February 2023, doi:

10.13140/RG.2.2.17088.40963

Vassileva, K. and Atanasova, M. (2014) Study of

transition boundaries in Bulgaria from GPS.

International symposium on modern technologies,

education and professional practice in geodesy and

related fields, Sofia, 06-07 November, 2014, 8.

Zagorchev, I. (2011) Cenozoic Block Rotations in the

Balkan Peninsula. Proceedings of 3rd nternational

Symposium of the Black Sea region, 1-10 October,

2011, Bucharest, Romania, 220-222

https://scihub.copernicus.eu/

http://step.esa.int/main/toolboxes/snap/

https://storymaps.arcgis.com/stories/355bfc8b3c5941e683

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