Geo log i cal Quar terly, 2021, 65: 14 DOI: http://dx.doi.org/10.7306/gq.1582
Tec tonic pulse reg is tered be tween 2013 and 2015 on the east ern mar gin of the Bo he mian Massif
Miloš BRIESTENSKÝ1, *, Josef STEMBERK1, Juraj LITTVA2, 3 and Rastislav VOJTKO3
1 Czech Acad emy of Sci ences, In sti tute of Rock Struc ture and Me chan ics, V Holešovièkách 94/41, 182 09 Prague, Czech Re pub lic
2 Slo vak Caves Ad min is tra tion, State Na ture Con ser vancy of the Slo vak Re pub lic, Hodžova 11, 031 01 Liptovský Mikuláš, Slovakia
3 Comenius Uni ver sity, De part ment of Ge ol ogy and Palae on tol ogy, Fac ulty of Nat u ral Sci ences, Mlynská dol ina, Ilkovièova ulica è. 6, 84215, Bratislava, Slovakia
Briestenský, M., Stemberk, J., Littva, J., Vojtko, R., 2021. Tec tonic pulse reg is tered be tween 2013 and 2015 on the east ern mar gin of the Bo he mian Mas sif. Geo log i cal Quar terly, 65: 14, doi: 10.7306/gq.1582
A sig nif i cant pe riod of in creased tec ton ics was mon i tored be tween 2013 and 2015 on the east ern mar gin of the Bo he mian Mas sif along ten faults. Nine of them showed a uni form scheme: dextral strike-slip along gen er ally NW–SE strik ing faults, sinistral strike-slip along gen er ally NE–SW strik ing faults and up ris ing of the south ern blocks. The dis tin guished fault dis - place ments dis played an NNW–SSE strik ing compressional com po nent of the stress field dur ing this re mark able tec tonic ep i sode.
Key words: tec tonic pulse, Bo he mian Mas sif, com pres sion, faults.
INTRODUCTION
An un der stand ing of the ac tive tec ton ics of re gional tec tonic struc tures re quires many years of mon i tor ing as well as a large amount of equip ment. A lo cal extensometric net work was es - tab lished on the east ern mar gin of the Bo he mian Mas sif to re - flect re cent up per crustal de for ma tion changes. Ten TM71 op ti - cal-me chan i cal gauges have been re cord ing three-di men sional dis place ments in this area. The first gauges were in stalled in the Skalka Gal lery in 1997, and sev eral were sub se quently in - stalled in the Pustožlebská zazdìná Cave in 2003, in the Na Turoldu Cave in 2008, in the Mladeè Caves in 2008, and in the 13C Cave in 2011. This type of mon i tor ing is on go ing at more than 150 sites through out Eu rope, and helps us to com pare the re sults and de fine si mul ta neous ac tiv ity af fect ing the whole of the Eu ro pean plate (Briestenský et al. 2015, 2018). This pa per pres ents data con cern ing the ori en ta tion and char ac ter of the stress field cre ated dur ing the sig nif i cant tec tonic pulse ob - served on the east ern mar gin of the Bo he mian Mas sif be tween 2013 and 2015. The re sults re veal the char ac ter of the tec tonic pulses, which may also be dif fer ent from the long-term ob ser va - tions. Fur ther more, the pa per high lights the im por tance of long-term tec tonic mon i tor ing.
GEOLOGICAL SETTING
The Bo he mian Mas sif rep re sents a re sult of Variscan Orog - eny. It was af fected by Al pine Orog eny and is sep a rated from the West ern Carpathians by the Carpathian Foredeep. The foredeep is con trolled by many ac tive fault zones, such as the Haná Fault Zone or the Diendorf–Èebín Fault Zone (Fig. 1).
The lat ter cre ates a SW–NE to SSW–NNE-strik ing zone known as the Diendorf Fault in the south and the Boskovice Fur row in the north (Fig. 1). Both struc tures were ini ti ated as duc tile shear zones with a sinistral strike-slip mech a nism in the Early Perm - ian (e.g., McCann, 2008). The Perm ian infill of the Boskovice Fur row half-graben was up lifted above the Cre ta ceous rocks of the Cre ta ceous ba sin dur ing Al pine tec ton ics (e.g., McCann, 2008). The Haná Fault Zone, which is in cor po rated into the so-called Nysa–Morava Zone, in cludes horst-and-graben struc tures, deep lin ear sed i men tary bas ins, Plio cene to Pleis to - cene al kali ba sic vol ca nism, and re cent CO2 fluxes. Ac tive tec - ton ics are ac com pa nied by low mag ni tude seis mic ity (Špaèek et al., 2015).
METHODOLOGY – ACTIVE FAULT MONITORING Fault dis place ments are mon i tored by spe cially de signed extensometric gauges, which help mea sure 3D de for ma tions and block ro ta tions in two planes per pen dic u lar to each other.
The long-term du ra bil ity of these in stru ments has been ver i fied e.g. at the Parohy site (Fig. 2) in the high moun tains of the West ern Carpathians (Briestenský et al., 2011). The site has
* Cor re spond ing au thor, e-mail: briestensky@irsm.cas.cz Re ceived: No vem ber 20, 2020; ac cepted: Jan u ary 14, 2021; first pub lished on line: March 23, 2021
been mon i tored with out any main te nance or re con struc tion since 1973. Only a gauge with out any elec tri cal com po nents such as a TM71 extensometer is able to sur vive such con di - tions. Most of the op ti cal-me chan i cal gauges mak ing up the extensometric net work EU-TecNet (www.tecnet.cz) are in - stalled un der the sur face, mostly in caves, which de creases the sea sonal tem per a ture ef fects that usu ally af fect the re ceived re sults (Briestenský el al., 2010a). The ac cu racy of the mea - sured fault dis place ments is greater than 10 µm per year. Re - cently, the meth ods and their de tailed ap pli ca tion were de -
scribed in de tail by Košïák (2006), Košïák et al. (2007, 2011), Gosar et al. (2009), Šebela et al. (2009), Stemberk et al. (2010, 2015), Briestenský et al. (2010, 2015, 2014a, 2014b), Klimeš et al. (2012), Marty et al. (2013), Rowberry et al. (2016) etc.
Due to fact that the re sults are usu ally pre sented in Car te - sian co or di nates, we have trans formed the sense of the sig nif i - cant dis place ment into a 3D vec tor (Ta ble 1), which are firstly de fined by two spher i cal val ues – plunge and az i muth (Briestenský et al., 2018). Sub se quently, the data were plot ted on the lower hemi sphere of the Equal-area stereonet us ing the Fig. 1. Lo ca tion of ten extensometric ob ser va to ries on the east ern Bo he mian Mas sif mar gin and the West ern Carpathians front
(adopted af ter Lenhardt et al., 2007)
The grey map in the up per-left cor ner shows the po si tion of the study area in Eu rope
Fig. 2. Re sults of very long-term mon i tor ing in the high moun tains of the West ern Carpathians at the Parohy site (Slovakia) The TM71 extensometric gauge was in stalled in 1973 and has dis played slow creep move ments in the scarp of a large Parohy slope de for - ma tion (Briestenský et al., 2010). The graph shows sep a rate dis place ment com po nents of the 3D space. The right pic ture shows the com - mon in stal la tion of the TM71 in stru ment in the Saeva Dupka Cave (Bul garia). The in stru ment is fixed in two op po site blocks, sep a rated by the mon i tored fault
Stereo32 soft ware (Röller and Trepmann, 2003) as de scribed in Briestenský et al. (2018). They were fur ther pro cessed us ing Win-Ten sor soft ware (Delvaux and Sprener, 2003). If the ori en - ta tion of the sig nif i cant dis place ment vec tor fell out side the cor - re spond ing planes, its ori en ta tion was ad justed to the clos est pos si ble fit onto the plane, in ac cor dance with Win-Ten sor’s sug ges tions. The Im proved Right Dihedron method based on the orig i nal method of Angelier and Melcher (1977) was sub se - quently used to sep a rate the data and to es ti mate the max i mum hor i zon tal stress (SHMAX) and mean stress axes (s1, s2, and s3).
Given the lim ited amount of data and the aim to pro vide only a rough es ti mate of the re duced ten sor, the data were not fur ther pro cessed us ing the ten sor Ro ta tional Op ti mi za tion method.
RESULTS
Fault dis place ments on the east ern mar gin of the Bo he mian Mas sif do not gen er ally dis play creep move ments with trends, but they are man i fested in so-called tec tonic pulses (Figs. 3 and 4). The pulses were pre vi ously de scribed by Stemberk et al. (2010) as a dis tin guished man ner of the ac tive tec ton ics of the Bo he mian Mas sif.
Our re sults show the most sig nif i cant pulse ob served in 2013–2015 on mar gin of the east ern Bo he mian Mas sif. The pulse showed nearly si mul ta neous dis place ments with sig nif i - cant strike-slip along nine of the mon i tored faults (Fig. 3). The strike-slip rep re sents a dis place ment com po nent that is not as - sumed to be caused by grav i ta tional pro cesses or hydrogeo - logical fac tors.
Dur ing the tec tonic pulse, the strike-slip dis place ment com - po nent was a prev a lent mode of dis place ment in the ma jor ity of the mon i tored faults; al though dip-slip was also oc ca sion ally pres ent (Ta ble 1 and Fig. 5). The NW–SE-strik ing faults had a dextral sense of strike-slip dis place ment, while the NE–SW to ENE–WSW-strik ing faults had a sinistral sense. The sinistral sense is in dis crep ancy with the de fined dextral strike-slip along the Diendorf–Èebín Fault Zone (Hausmann et al., 2010; Brückl et al., 2010). On the other hand, our ob ser va tion is in good con - for mity with the re sults from the Driny Cave (the Cen tral West - ern Carpathians), lo cated to the east in the Malé Karpaty Mts.
(Slovakia). Here, the fault dis place ment mon i tor ing dis plays a
sinistral strike-slip along NNE–SSW strik ing faults, a dextral strike-slip along NW–SE strik ing faults, and an NNW–SSE ori - ented compressional com po nent of the stress field (Briestenský et al., 2010).
Of the ten sig nif i cant dis place ments vec tors, two were sep - a rated and ex cluded from the fur ther anal y sis dur ing the soft - ware sep a ra tion of the data in Win-Ten sor. These ex cluded vec tors were prob lem atic in sev eral ways. The first of the ex - cluded vec tors was from the mea sure ments taken from in the 13C Cave, where two sig nif i cant dis place ment senses were found. The ex cluded vec tor rep re sents a nor mal move ment, which al most com pletely re bounded within half a year (Fig. 3). A sim i lar re bound, al beit in a shorter timeframe, was also ob - served in the sec ond of the ex cluded dis place ment vec tors mea sured at Skalka Gal lery (Fig. 4). More over, the mea sure - ment came from the only sur face lo cal ity of this study and the dis place ment vec tor was one of the three vec tors that had to be ad justed onto the fault plane.
The cal cu lated data of es ti mated stress ori en ta tion from the re main ing dis place ment vec tors fur ther sup ports the no tion of the strike-slip re gime with NNW–SSE-strik ing max i mum com - pres sion in the stud ied area in the pe riod be tween 2013 and 2015 (Fig. 5). Us ing the Im proved Right Dihedron method, the stress ori en ta tion was de ter mined as fol low ing: az i muth 345.2 ±5.9 for the SHMAX and the az i muth/plunge 341/29 (±14.6) for s1, 193/56 (±16.9) for s2, and 78/15 (±13.3) for s3 (with strike-slip tec tonic re gime). The count ing de vi a tion was 24.4 ±4.
These re sults show that fault-slip anal y sis of the move ments ob tained from 3-D mon i tor ing of ac tive faults may be used to pro vide a rough es ti mate of the prin ci pal stress ori en ta tion (see also Stemberk et al., 2019a). Fur ther more, we spec u late that given a suf fi cient amount of data these meth ods may be used to re li ably de ter mine the ori en ta tion of the stress ten sor of re cent crustal stresses. Our re sults are in good con for mity with GPS stud ies (Pospíšil et al., 2012, 2017), which showed a dextral strike-slip along NW–SE-strik ing faults (Nectava–Konice Fault) and a sinistral strike-slip along NE–SW-strik ing faults (Boskovice Fur row, Diendorf Fault, Bulhary Fault) in the east - ern part of the Bo he mian Mas sif (Fig. 1). More over, com puted stress-field ori en ta tion is in good con for mity with the re sults from neigh bour ing ar eas: (1) NW–SE ori ented hor i zon tal com - pres sion in the Outer West ern Carpathians (Jarosiñski, 1998, Miloš Briestenský et al. / Geo log i cal Quar terly, 2021, 65: 14 3
T a b l e 1 Sense of sig nif i cant fault dis place ments mon i tored on the east ern Bo he mian Mas sif mar gin dur ing the no tice able pe riod be tween 2013 and 2015, data were used for ste reo graphic pro jec tion and the compressional com po nent of the re cent stress
field com pu ta tion
Fig. 3. The fault dis place ments re corded on the east ern mar gin of the Bo he mian Mas sif
In creased fault ing ac tiv ity be gan in 2013 and fin ished in the first half of 2015. The Pustožlebská zazdìná Cave dis played grad ual fault ing from the cen tre of the mas sif to the edge (from the in te rior to the en trance). The graphs on the left show the be gin ning of the fault ing on 12 De - cem ber 2013, when strike-slips were ac ti vated in the 13C Cave and si mul ta neously in the Mladeè Caves. Both sites are 103 km apart (strik - ing 15.26°)
Fig. 4. Dis place ments reg is tered across the mon i tored fault in the Skalka Gal lery (site No. 334, see Table 1) Dip-slips and strike-slips dis played re mark able re ver sals in 2014
Miloš Briestenský et al. / Geo log i cal Quar terly, 2021, 65: 14 5
Fig. 5. Sense of strike-slips mon i tored along the faults on the east ern mar gin of the Bo he mian Mas sif dur ing the sig nif i cant tec tonic pulse be tween 2013 and 2015
The ste reo graphic pro jec tion on the right shows the fault planes (black great cir cles) and dis place ment vec tors (pro jected as points).
Ad just ment of the lineation in the WinTensor soft ware is in di cated by dashed lines and red col our and ex cluded data are in di cated by the grey col our. Com puted mean stress axes are in the cen tre
Fig. 6. Dis tri bu tion of half-yearly earth quakes be tween 2011 and 2016 and monthly dis tri bu tion be tween 2013 and 2014 in the cir cle with a ra dius of 1600 km from the 13C Cave (Cen tre: 49.40N; 16.77E)
The first two months of 2014 show in creased earth quake ac tiv ity all over Eu rope (source: https://earth quake.usgs.gov/earth quakes), which is in good con for mity with reg is tered fault ing ac tiv ity on the east ern Bo he mian Mas sif mar gin. The lower-right graph shows the time
dis tri bu tion and a list of lo cal earth quakes ob served on the east ern mar gin of the Bo he mian Mas sif (source: www.emsc-csem.org)
2005; Stemberk et al., 2016), (2) NNW–SSE (Havíø, 2004) and WNW–ESE/NW–SE (Stemberk et al., 2019b) in the Jeseníky re gion, (3) the Czech part of the Up per Silesian ba sin (Peška, 1992), (4) NNW–SSE in the cen tral West ern Carpathians (Briestenský et al., 2010b), (5) NW–SE in the Nisa–Morava Zone (Špaèek et al., 2015).
The sig nif i cant pe riod be tween 2013 and 2015 led us to search for cor re la tions with seis mic ity. Here, the fault ing be gan in the first half of 2013 in at the Pustožlebská zazdìná Cave No. 1 (Fig. 3) and dur ing this pe riod, three lo cal earth quakes were mon i tored in the area of the east ern Bo he mian mar gin.
More over, no tice able mu tual fault ing be gan in De cem ber 2013, which was ob served on the south ern most site of the Na Turoldu Cave and in the north ern most Mladeè Caves (dis tance = 103 km, Fig. 3). The au to matic data col lec tion in the 13C Cave re vealed the start of the late au tumn fault ac ti va tion on 12 De - cem ber 2013.
The strike-slip dis place ments also con tin ued un til the first half of 2015 in the Na Turoldu Cave (Site No. 2; Fig. 2). More - over, the start of the fault ing at the end of 2013 was fol lowed by in creased seis mic ac tiv ity on the Eu ro pean Plat form (Fig. 6), re - gard ing events in a cir cle with a ra dius of 1600 km (source:
https://earth quake.usgs.gov/earth quakes). This fact shows that the fault ing was not evoked by in creased seis mic ity, but both phe nom ena dis played ac cel er ated tec ton ics at the end of 2013 and the be gin ning of 2014. Fig ure 6 shows monthly earth quake sums of 2013 and 2014 with in creased seis mic ity in Jan u ary 2014.
DISCUSSION
Re gard ing our stress-field re sults from 2013 to 2015, ob - served on the east ern mar gin of the Bo he mian Mas sif, and the above-men tioned re ports from the other Carpathian foredeep sites, a sig nif i cant pat tern may be no ticed. The re ported stress-field ori en ta tions are gen er ally de fined as per pen dic u lar to the Carpathian Arc (Jarosiñski, 2005; Špaèek et al., 2015;
Hók et al., 2016), re ferred to as the con tin ual re cent ALCAPA push (Jarosinski, 2005). There fore, NNW–SSW strik ing SHmax, dur ing the pre sented 2013–2015 pe riod, slightly de vi ates from the gen eral scheme. A study from the Up per Silesian Coal Ba - sin (Mendecki et al., 2020) re veals more sig nif i cant dis crep - ancy. The re sults of seis mic mo ment ten sor in ver sion in the area of the Bytom Syncline show the com pres sion act ing in an NE–SW di rec tion. This de vi ates from the ex pected gen eral
NW–SE di rec tion. More over, Stemberk et al. (2019b) de scribed two switch ing compressional stress/strain states – WNW–ESE to NW–SE com pres sion and the NNE–SSW com pres sion in the Dìdièná štola Gal lery in the Rychlebské hory Mts. dur ing the pe riod be tween 2014 and 2017. It may be spec u lated that these de vi a tions are pro duced by the episodical clock wise or coun ter clock wise ro ta tion of the ALCAPA microplate. This phe - nom e non was de scribed for the pre vi ous de vel op ment of the unit. For ex am ple, af ter the early Mio cene tec tonic phase, the West ern Carpathian push was ac com pa nied by a coun ter clock - wise ro ta tion of ~60° with re spect to the Eu ro pean Plat form (Márton et al., 1999).
CONCLUSIONS
Our extensometric mon i tor ing showed a sig nif i cant in crease in tec tonic ac tiv ity in the pe riod be tween 2013 and 2015 on the east ern mar gin of the Bo he mian Mas sif. Dur ing this time, fault mi cro-dis place ments al lude to the fol low ing uni form scheme:
dextral strike-slip along gen er ally NW–SE strik ing faults, sinistral strike-slip along gen er ally NE–SW strik ing faults and up lift of the south ern blocks. These em i nent microdisplace - ments were uti lized in the soft ware fault-slip anal y ses to de ter - mine the ori en ta tion of the prin ci pal stresses that gen er ated them – an ap proach that to our knowl edge has only been tried in a few other stud ies in this par tic u lar field. The es ti mate of the stress ten sor cal cu lated by the Win-Ten sor pro gram shows a strike-slip stress-field with the main com pres sion axis hav ing an NNW–SSE ori en ta tion. In creased mu tual microdisplacements oc curred in De cem ber 2013 in the whole space, and fol low ing in creased seis mic ac tiv ity in Eu rope in Jan u ary 2014, sup port the im por tance of the ob served dis place ments on the nine mon - i tored fault struc tures. This fact pro vides a cor re la tion be tween these two phe nom ena.
Ac knowl edge ment. We thank D. Coufalová and J. Kolaøík for their help with mon i tor ing and as sis tance dur ing the field - work. The re search was sup ported by the long-term con cep tual de vel op ment re search or ga ni za tion RVO: 67985891; APVV pro jects No. APVV-0099-11 and No. APVV-0315-12 and the infrastructural pro jects CzechGeo (LM2015079) and CzechGeo/EPOS-Sci CZ.02.1.01/0.0/0.0/16_013/0001800.
The sci en tific re sults were ob tained us ing Win-Ten sor, a soft - ware de vel oped by Dr. D. Delvaux, Royal Mu seum for Cen tral Af rica, Tervuren, Bel gium.
REFERENCES
Angelier, J., 1984. Tec tonic anal y sis of fault slip data sets. Jour nal of Geo phys i cal Re search, 8: 5835–5848.
Angelier, J., 1989. From ori en ta tion to mag ni tudes in paleostress de ter mi na tions us ing fault slip data. Jour nal of Struc tural Ge ol - ogy, 11: 37–50.
Angelier, J., 1990. In ver sion of field data in fault tec ton ics to ob tain the re gional stress – III. A new rapid di rect in ver sion method by an a lyt i cal means. Geo phys i cal Jour nal In te rior, 103: 363–376.
Angelier, J., 1994. Fault slip anal y sis and Paleostress re con struc - tion. In: Con ti nen tal De for ma tion (ed. P. L. Han cock): 53–100.
Pergamon Press, Bris tol.
Angelier, J., Taranola, A., Valette, W., Manousis, S., 1982. In ver - sion of field data in fault tec ton ics to ob tain the re gional stress – I. sin gle-phase fault pop u la tions: a new method of com put ing
the stress ten sor. Geo phys i cal Jour nal In ter na tional, 69:
607–621.
Angelier, J., Melcher, J., 1997. Sur une method graphique de recherché des contraintes contraintes principales egalement uti lis able en tectonique et en seismologie: la methode des diedres droits. Bul le tin de la Société Géologique de France, 7:
1309–1318.
Briestenský, M., Košïák, B., Stemberk, J., Petro, ¼., Vozár, J., Fojtíková, L., 2010a. Ac tive tec tonic fault microdisplacement anal y ses: a com par i son of re sults from sur face and un der - ground mon i tor ing in west ern Slovakia. Acta Geodynamica et Geomaterialia, 7: 387–397.
Briestenský, M., Stemberk, J., Michalík, J., Bella, P., Rowberry, M.D., 2010b. The use of a karstic cave sys tem in a study of ac -
tive tec ton ics: fault move ments re corded at Driny Cave, Malé Karpaty Mts. (Slovakia). Jour nal of Cave and Karst Stud ies, 73:
114–123.
Briestenský, M., Košïák, B., Stemberk, J., Vozár, J., 2011.
Long-term slope de for ma tion mon i tor ing in the high moun tains of the West ern Carpathians. Acta Geodynamica et Geoma - terialia, 8: 403–412.
Briestenský, M., Stemberk, J., Rowberry, M.D., 2014a. The use of dam aged speleothems and in situ fault dis place ment mon i tor ing to char ac ter ise ac tive tec tonic struc tures: an ex am ple from Západní Cave, Czech Re pub lic. Acta Carsologica, 43: 129–138.
Briestenský, M., Thinová, L., Praksová, R., Stemberk, J., Rowberry, M.D., Knejflová, Z., 2014b. Ra don, car bon di ox ide, and fault dis place ments in cen tral Eu rope re lated to the Tôhoku Earth quake. Ra di a tion Pro tec tion Do sim e try, 160: 78–82.
Briestenský, M., Rowberry, M.D., Stemberk, J., Stefanov, P., Vozár, J., Šebela, S., Petro, ¼., Bella, P., Gaal, ¼., Ormukov, Ch., 2015. Ev i dence of a plate-wide tec tonic pres sure pulse pro - vided by extensometric mon i tor ing in the Bal kan Moun tains (Bul garia). Geologica Carpathica, 66: 427-438.
Briestenský, M., Hochmuth, Z., Littva, Hók, J., Dobroviè, R., Stemberk, J., Petro, ¼., Bella, P., 2018. Pres ent-day stress ori - en ta tion and tec tonic pulses reg is tered in the caves of the Slovenský kras Mts. (South-East ern Slovakia). Acta Geodynamica et Goematerialia, 15: 93–103.
Brückl, E., Behm, M., Decker, K., Grad, M., Guterch, A., Keller, G.R., Thybo, H., 2010. Crustal struc ture and ac tive tec ton ics in the East ern Alps. Tec ton ics, 29, TC2011.
Delvaux, D., Sperner, B., 2003. Stress ten sor in ver sion from fault ki ne matic in di ca tors and fo cal mech a nism data: the TENSOR pro gram. Geo log i cal So ci ety Spe cial Pub li ca tions, 212: 75–100.
Gosar, A., Šebela, S., Košïák, B., Stemberk, J., 2009. Sur face ver sus un der ground mea sure ments of ac tive tec tonic dis place - ments de tected with TM 71 ex ten som eters in west ern Slovenia.
Acta Carsologica, 38: 213–226.
Hausmann, H., Hoyer, S., Schurr, B., Brückl, E., House man, G., Stu art, G., 2010. New seis mic data im prove earth quake lo ca - tion in the Vi enna Ba sin area, Aus tria. Aus trian Jour nal of Earth Sci ences, 103: 2–14.
Havíø, J., 2004. Ori en ta tion of re cent prin ci pal stress axes in the Jeseníky re gion. Acta Geodynamica et Goemoaterialia, 1:
49–57.
Hók, J., Kysel, R., Kováè, M., Moczo, P., Kristek, J., Kristeková, M., Šujan, M., 2016. A seis mic source zone model for the seis - mic haz ard as sess ment of Slovakia. Geologica Carpathica, 67:
273–288.
Jarosiñski, M., 1998. Contemorary stress field dis tor tion in the Pol - ish part of the West ern Outer Carpathians and their base ment.
Tectonophysics, 297: 91–119.
Jarosiñski, M., 2005. On go ing tec tonic re ac ti va tion of the Outer Carpathians and its im pact on the fore land: Re sults of bore hole break out mea sure ments in Po land. Tectonophysics, 410:
189–216.
Klimeš, J., Rowberry, M.D., Blahùt, J., Briestenský, M., Hartvich, F., Košïák, B., Rybáø, J., Stemberk, J., Štìpanèíková, P., 2012. The mon i tor ing of slow-mov ing land slides and as sess - ment of sta bili sa tion mea sures us ing an op ti cal-me chan i cal crack gauge. Land slides, 9: 407–415.
Košïák, B., 2006. De for ma tion ef fects in rock mas sifs and their long-term mon i tor ing. Quar terly Jour nal of En gi neer ing Ge ol ogy and Hydrogeology, 39: 249–258.
Košïák, B., Cacoñ, S., Dobrev, N.D., Avramova-Tacheva, E., Fecker, E., Kopecký, J., Petro, ¼., Schweizer, R., Nikonov, A.A., 2007. Ob ser va tions of tec tonic microdisplacements in Eu - rope in re la tion to the Iran 1997 and Tur key 1999 earth quakes.
Izvestiya Phys ics of the Solid Earth, 43: 503–516.
Košïák, B., Mrlina, J., Stemberk, J., Chán, B., 2011. Tec tonic move ments mon i tored in the Bo he mian Mas sif. Jour nal of Geodynamics, 52: 34–44.
Lenhardt, W.A., Švancara, J., Melichar, P., Pazdírková, J., Havíø, J., Sýkorová, Z., 2007. Seis mic ac tiv ity of the Al -
pine-Carpathian-Bo he mian Mas sif re gion with re gard to geo log - i cal and po ten tial field data. Geologica Carpathica, 58:
397–412.
Marti, X., Rowberry, M.D., Blahùt, J., 2013. A MATLAB® code for count ing the moiré in ter fer ence fringes re corded by the op ti - cal-me chan i cal crack gauge TM-71. Com put ers & Geoscien - ces, 52: 164–167.
Márton, E., Mastella, L., Tokarski, A.K., 1999. Large coun ter clock - wise ro ta tion of the In ner West ern Carpathian Paleogene flysh – Ev i dence from paleomagnetic in ves ti ga tions of the Podhale Flysh (Po land). Phys ics and Chem is try of the Earth, Part A:
Solid Earth and Ge od esy, 24: 645–649.
McCann, T., 2008. The Ge ol ogy of Cen tral Eu rope, 2: Me so zoic and Ce no zoic. Geo log i cal So ci ety, Lon don.
Mendecki, J.M., Szczygiel, J., Lizurek, G., Teper, L., 2020. Min - ing-trig gered seis mic ity gov erned by a fold hinge zone: The Up - per Silesian Coal Ba sin, Po land. En gi neer ing Ge ol ogy, 274:
105728.
Peška, P., 1992. Stress in di ca tions in the Bo he mian Mas sif: re in ter - pre ta tion of bore hole televiewer data. Studia Geographica at Godaetica, 36: 307–324.
Pospíšil, L., Roštínský, P., Švábenský, O., Weigel, J., Witiska, M., 2012. Ac tive tec ton ics in the east ern mar gin of the Bo he - mian Mas sif – based on geo phys i cal, geomorphological and GPS data. Acta Geodynamica et Geomaterialia, 9: 315–329.
Pospíšil, L., Švábenský, O., Roštínský, P., Nováková, E., Weigel, J., 2017. Geodynamic risk zone at north ern part of the Boskovice Fur row. Acta Geodynamica et Geomaterialia, 14:
113–129.
Rowberry, M.D., Kriegner, D., Holy, V., Olejnik, K., Llull, M., Frontera, C., Marti, X., 2016. The in stru men tal res o lu tion of a moiré extensometer in light of its re cent au tom a ti za tion. Mea - sure ments, 91: 258–265.
Röller, K., Trepmann, C. A., 2003. Stereo32, soft ware, Ruhr Universität, Bochum, Ger many, http://www.ruhr-uni-bochum.de/
hardrock/down loads.html
Sperner, B., Müller, B., Heidbach, O., Delvaux, D., Reinecker, J., Fuchs, K., 2003. Tec tonic stress in the Earth’s crust: ad vances in the World Stress Map pro ject. Geo log i cal So ci ety Spe cial Pub li ca tions, 212: 101–116.
Stemberk, J., Košïák, B., Cacoñ, S., 2010. A tec tonic pres sure pulse and in creased geodynamic ac tiv ity re corded from the long-term mon i tor ing of faults in Eu rope. Tectonophysics, 487:
1–12.
Stemberk, J., Briestenský, M., Cacoñ, S., 2015. The rec og ni tion of tran sient compressional fault slow-slip along the north ern shore of Hornsund Fjord, SW Spitsbergen, Svalbard. Pol ish Po - lar Re search, 36: 109–123.
Stemberk, J., Hartvich, F., Blahút, J., Rybáø, J., Krejèí, O., 2017.
Tec tonic strain changes af fect ing the de vel op ment of deep seated grav i ta tional slope de for ma tions in the Bo he mian Mas sif and Outer West ern Carpathians. Geo mor phol ogy, 298: 3–17.
Stemberk, J., Dal Moro, G., Stemberk, J., Blahùt, J., Coubal, M., Košïák, B., Zambrano, M., Tondi, E., 2019a. Strain mon i tor ing of ac tive faults in the cen tral Apennines (It aly) dur ing the pe riod 2002–2017. Tectonophysics, 750: 22–35.
Stemberk, J., Coubal, M., Stemberk, J., Štìpanèíková, P., 2019b.
Stress anal y sis of fault slips data re corded within the Dìdièná štola gal lery in the Rychlebské hory Mts., NE part of the Bo he - mian Mas sif. Acta Geodnymica et Geomaterialia, 16: 315–330.
Šebela, S., Turk, J., Mulec, J., Košïák, B., Stemberk, J., 2009.
Sta tis ti cal eval u a tion of the 3D mon i tor ing of dis place ments of Dinaric Fault zone in Postojna Cave, Slovenia. Acta Geodynamica et Geomaterialia, 6: 163–176.
Špacek, P., Bábek, O., Štepancíková, P., Švancara, J., Pazdírková, J., Sedláèek, J., 2015. The Nysa Morava Zone: an ac tive tec tonic do main with Late Ce no zoic sed i men tary grabens in the West ern Carpathians’ fore land (NE Bo he mian Mas sif). In - ter na tional Jour nal of Earth Sci ences, 104: 963–990.
Miloš Briestenský et al. / Geo log i cal Quar terly, 2021, 65: 14 7
