Research of the Horizontal Crustal Motions, Based on GPS Data for the Territory of Bulgaria and the Balkans (7093)

Transcription

1 Natonal Insttute of Geophscs, Geodes and Geograph Bulgaran Academ of Scences Bulgaran Chamber of Graduated Surveors Research of the Horzontal Crustal Motons, Based on GPS Data for the Terrtor of Bulgara and the Balkans (7093) Mla ATANASOVA-ZLATAREVA, (Bulgara) SUMMARY The present stud s focused on the used GPS data from free avalable GNSS statons on the terrtor of the Balkans. Applng veloctes and respectve coordnates of the statons estmated from GPS data processng, t s possble to estmate the rotaton Euler vector b Least Squares Method. For determnaton of Euler parameters I accepts a set of GPS statons as stable. Several dfferent rotaton poles have been estmated n order to test the proposed knematcs model for Bulgara. The presented veloct gradent clearl ndcates the ncrease of the moton from north to south. The GPS derved veloct feld from GPS statons coverng the terrtor of Bulgara has been analsed and dscussed n the contet of tectonc block models. Ths paper covers an mportant topc, where GPS data has now been collected for enough ears to be able to be used for revewng plate movements. The man purpose of ths work s to estmate and nfer coordnates and veloct vectors of a set of statons, and to determne rotaton parameters, usng GPS data. XXV Internatonal Federaton of

2 INTRODUCTION The terrtor of Bulgara and partcular the regon of Balkan Pennsula characterzes wth actve tectoncs and sesmotectoncs. Repeated GPS surves n Bulgara provde a drect measurement of current crustal motons. GPS surves have been carred out n ths regon snce The horzontal crustal movement have been studed b GPS analss n (Burchfel et al., 2006, Georgev et al., 2013, Kotzev et al, 2008, Matev K., 2011). The regon of South Bulgara, especall Southwest Bulgara and Rhodopes Mountans and Northern Greece s an actve tectonc and sesmotectonc area n the South Balkans wth proved recent actve tectonc structures and crustal motons. Based on these boundares, geologcal structures and faults, I formed the contours of the blocks structure, n t research. The GPS veloct felds are estmated and the are used to estmate the block rotaton motons. Blocks rotatons are dscussed n detals b the stud of GPS measurements, geolog structural, and sesmct and paleomagnetc measurement, whch contrbute XXV Internatonal to more Federaton precse of and clear determnaton of the transton zone. Fg.1. Poston fault from terrtor of Bulgara and the part of Balkans, Southern Balkan Etensonal Regon (SBER) (Kotzev et al, 2008) and Martza lneament (ML) (Georgev I., (2009) XXV Internatonal Federaton of

3 METHODS The veloct feld of blocks can be determned b ther relatve dsplacement feld of stable pont groups. Accordng to rgd knematcs theor and regardng the crust as a rgd bod, we can establsh knematcs model. Usng the veloctes, and the respectve coordnates of the statons estmated b GPS, t s possble to estmate the rotaton Euler vector n a Least Square adjustment. Usng the ver well known Euler theorem, the movement of blocks can be descrbed b Euler vector, and the vector can be gotten from the lnearzed observaton equaton for one staton (Perez et al., 2003): V = Ω.X, or (1) v v v z = 0 Ω z Ω Ω 0 Ω z Ω Ω 0 X. Y Z XXV Internatonal Federaton of (2) It s also possble to wrte an observaton equaton smlar to eq. (2) based on the sphercal coordnates and so also north, east and vertcal components n veloct. Because of the poor precson of GPS n vertcal drecton, we dscard t and onl use east veloct and north veloct to compute (Xu Cajun et al., 2000) v v n e = R. sn λ. Ω R.cos λ. Ω (3) = R. snϕ.cosλ. Ω R.sn λ.snϕ. Ω + R.cosϕ. Ω z z Ω = Ω + Ω + Ω (4) Ω z Φ = arcsn Ω Ω Λ = arctan Ω R- mean radus of Earth. Ω, Ω, Ω Thez - angle veloct n results and ther precsons coordnate are aes showed X,Y,Z; n Table 3. We have ϕ estmated the Euler parameters, of each block wth.. And.... λ - longtude and lattude of the pont Euler vector parameters : Ω s angle veloct Φ, Λ are Euler polar coordnates. XXV Internatonal Federaton of

4 GPS DATE Two dfferent knds of GPS networks are used to montor and determne present-da dsplacements on the terrtor of Bulgara and the Balkans.The networks nclude observaton from permanent statons IGS ( EPN stes (most of the IGS stes are part of EUREF), HemusNet permanent statons ( HemusNet permanent GPS network was establshed n 2007 under nternatonal project Scence for Peace Program, NATO: SFP (Montorng Crustal deformaton n West Central Bulgara and Northern Greece usng GPS). The am of the project s to provde basc nfrastructure n both Bulgara and Northern Greece for navgaton, surveng, scence, engneerng, and atmospherc sensng. The network contans 8 permanent statons that cover West-Central Bulgara and Northern Greece. The second knd GPS data, who are used are campagns measurements for the15 ponts of the precse BULREF network, adopted for offcall realzaton of ETRS89 n Bulgara. BULREF network The ntal observatons were carred out n two campagns 1992 and 1993 (Altner Y. et al., 1996). Seven ponts from ths network are offcall accepted as etenson of EUREF wth accurac class B. The ponts from the BULREF network were measured durng the perod , for XXV Internatonal Federaton of the varous projects and campagns b several author's groups (Altner et al., 1996, Kotzev V., et. al. 2001, Vasleva K. et. al. 2004, Georgev I. et al. 2009). XXV Internatonal Federaton of

5 Table 1. BULREF statons usng n campagn processng NAME PETR X X X X X X X HARM X X X X GABR X X X X X X VIDI X X X X KAVA X X X X X SOFI X X X X X X X BURG X X X X X X SAPA X X X X X X SATO X X X X X X GULI X X X SHUM X X X X KERM X X X MAMA X X X BERK X XXV Internatonal X Federaton X of X X X PANA X Surveors X Congress, Kuala X X To estmate current dsplacements, we have used data for the 15 BULREF ponts. GPS measurements carred out n 1996, 1997, 1998 wthn the frames of nternatonal project wth Massachusetts Insttute of Technolog (MIT) (Geodnamc settngs of Bulgara n the actve and oung Near East- Balkan geotectonc sstem) (Kotzev et. al. 2001). In epoch ths 15 ponts are observaton, adjustment and nclude of the Natonal GPS network-based class sstem ETRF2000 (Georgev I., et al. 2005). Statons were processed wth the same software, n the one same coordnate sstem ETRF2000. For the local movements of the statons, whch are more mportant for ours, ETRF horzontal veloct vectors have been obtaned b applng ETRF components of the Eurasa plate rotaton pole (Boucher, Altamm, 2008) from the obtaned ITRF2005 veloct vectors. Then the have been transformed nto ETRF2000 (Atanasova M,. 2013a,. Atanasova M,. 2013b) Table 2. GPS coordnates and veloctes and ther mean square errors wth respect to the stable Eurasan XXV Internatonal Federaton of

6 n a m e λ ϕ n v σ e v n v v e σ v α B lo c k N B B U C U V I D I C O S T B E R K S H U M G A B R G U L I K A V A V A T G B lo c k S E B H A R M K E R M M A M A P A N A P A Z A B U R G I S T A B lo c k S W B S O F A S O F I D R A G K U S T S A P A P E T R S A T O S A N D Y U N D R O G H O R I D XXV N ointernatonal rt h e r n G r e e c e Federaton of A U T T E I S L E M N The obtaned veloct feld of the Earth s crust s represented b 30 ponts n Bulgara and encompassng the regon. (Fgure 2).The results show southward dsplacements between mm/r. GPS results gve detaled nformaton on the dsplacements. The presented veloct gradent clearl ndcates the ncrease of the moton from north to south and reaches the Hellenc arc wth values of up to 30mm/r. The etensonal zone passes through Central Bulgara along an appromatel east-west trend separatng a northern regon wth nsgnfcant moton relatve to Eurasa from south-western regon characterzed b E-W etensonal grabens and ncreasng southward veloctes between 2-3mm/r) Several dfferent rotaton poles coverng dfferent scale of areas have been tested to ft better wth the observed veloctes. B ths reason two man sets are confgured from all statons n Northern Bulgara and two statons n Romana and respectvel from all statons n Southern Bulgara, Northern Greece and Northern Turke and Macedona. Usng 9 GPS ponts I suggest a Block to name NB, whch reaches the Stara Planna Mountan of south. On Fgure 2 s shown proposed NB block (blu ponts) defned wth Euler pole of rotaton around Frst I want to fnd a large sngle block SB, whch conssts of statons onl n southern Bulgara, Northern Greece and Northern Turke and Macedona, calculatng rotaton pole usng 21GPS statons The obtaned msfts between the observed and model veloctes are ver bg. The presented b the msfts results are not consstent wth the proposed and clearl show that there s no rgd block whch can perform the current dsplacement shown through our stud as sngle stable block wthn such large area. XXV Internatonal Federaton of

7 XXV Internatonal Federaton of I dvded ths large area nto two small blocks and boundares passes through Martza lneament passng NW-SE. The block stuated east of the Martsa lneament s named SEB and ts boundares to the north s Stara planna Mountan and the Black Sea to the east. Wth 7 GPS statons (red ponts) located of SEB The regon of Southwest Bulgara (SWB) has the most pronounced tectonc and sesmotectonc actvt on the whole Bulgaran terrtor (Shanov et al. 2001). Usng 10 GPS statons (black ponts) on areas n SWB and 2 GPS statons on NG terrtor, 1 GPS statons on terrtor Macedona I estmated rotaton pole. Wth those areas the obtaned msfts results stll do not provde good fttng. The msfts decrease wth the decreasng the scale of blocks area. I ndcated 2 blocks that present better fttng between observed and model vectors A set of 4 ponts (DRAG, SOFA, SOFI, KUST) are used to defne a block correspondng to the observed veloctes (SWB blok SOFI ) and a set of 7 ponts (PETR, SAND, SAPA, SATO YOND, ROGH, ORID) are used to defne a block correspondng to the observed veloctes (SWB block PETR ) The smaller on block sze gves better fttng between observed and model veloctes The estmated parameters of the rotaton pole are lsted n Table 3. These results obtaned b analss of GPS data set are n agreement wth the XXV Internatonal Federaton of obtaned b result of other scentsts (Georgev et al., 2011, Matev K., 20111)

8 Fgure 3. Schematc mappng of block structure SWB nferred from GPS results. XXV Internatonal Federaton of Table 3. Euler Parameters of Blocks deduced from the veloctes Name of Blocks Euler Longttude Euler lattude Ω Λ E Φ N /Ma. 1.Northern Bulgara - NB Southern Bulgara - SB South-East - SEB South-West - SWB Block SOFI Block PETR XXV Internatonal Federaton of

9 CONCLUSION The obtaned veloctes from the GPS data processng ndcate an overall moton to the south. The results show an ncreasng rate from mm/r n Centralwest Bulgara to 10 mm/r for the Northern Greece confrmng the north-south etensonal regme n the regon. The horzontal veloctes n North Bulgara, confrm the suggeston that North Bulgaran terrtor s part of the Eurasan plate. Our results show that the Southwest Bulgara do not belong to the Eurasan plate and seem to move the south wth the veloctes relatve to Eurasa graduall ncrease n N-S drecton from 1.5 mm/r n western Bulgara to 10mm/r n the Northern Greece. XXV Internatonal Federaton of THANK YOU FOR YOUR ATTENTIION XXV Internatonal Federaton of