earthquakes on the eastern margin of the bohemian massif recorded
Transkript
earthquakes on the eastern margin of the bohemian massif recorded
“Exploration Geophysics, Remote Sensing and Environment“ V. 2. (1998) EARTHQUAKES ON THE EASTERN MARGIN OF THE BOHEMIAN MASSIF RECORDED BY THE STATIONS OF THE IPE BRNO 1Skácelová, Z.,1Havífi,J. 1Institute of Physics of the Earth, Faculty of Sciences, Masaryk University, Tvrdého 12, 602 00 Brno Czech Republic ABSTRACT: The latest results of the seismological analysis in the eastern margin of the Bohemian Massif are discussed. The stations of the Institute of Physics of the Earth (IPE) have detected in this region 131 tectonic microearthquakes since 1992. Twenty tectonic events were localised by program HYPO3D. The localisations of epicentres indicate affinity of the seismo-tectonic activity mainly to the NW-SE trending movements along the faults. SEISMOLOGICAL STATIONS INTRODUCTION Four seismic stations in the Moravian and Silesian regions have been built up by the Institute of Physics of the Earth, Faculty of Sciences, Masaryk University, Brno (IPE) since 1992. The first of them, the VRAC station in Vranov u Brna (approximately 15 km from the city of Brno) was registering in trigger regimen (triggered records of particularly strong events) from 1992 to 1993, and since 1993 in continuous regimen. The VRAC station is now included into International Monitoring System for verification of an adherence of Nuclear Test Ban Treaty. It is equipped with the three-component wide-range sensor TSJ-1 and the Lennartz 5800 registering apparatus. Registered data are transmitted to the National Data Centre in Brno (NDC), stored on the hard drive where they are immediately available for interpretation (approximately 10 minutes delayed). The tectonic setting of the eastern part of the Bohemian Massif is represented by at least three structural levels (Cadomian, Variscan and Alpine). During the Alpine Orogeny the Western Carpathian flysh nappes were thrust over the eastern margin of the Bohemian Massif owing to an oblique collision. The Alpine compression affected the geological units of the whole Bohemian Massif by significant movements along the fault zones. The older (Variscan) structures were often involved in the younger tectonic movements in the eastern part of the Bohemian Massif. The seismic activity in the eastern margin of the Bohemian Massif (Moravia and Silesia) is relatively weak. Strong earthquakes, known from historical records, were mainly concentrated into the Opava, ·ternberk, and Hrub˘ Jeseník regions. Macroseismic earthquake manifestations in these regions were described in chronicles and historical archives (Reme‰ 1902; Koláãek 1921; Schenková, Kárník and Schenk 1980). But most of them were assigned to the strong earthquakes in the Viennna Basin (Olomouc and ·ternberk areas). In October 1993 the MORC station (Moravsk˘ Beroun) was put into operation within the framework of the international project GEOPHON. It is situated on the âervená Hill in the epicentral area of earthquakes originated in the area of Opava, ·ternberk, and Hrub˘ Jeseník. Since November 1995 another two stations have been in operation - the KRUC (Moravsk˘ Krumlov) and JAVC (Javorina) stations. They are situated in southern Moravia, the KRUC station approximately 50 km SW of Brno and the JAVC station in the border region with Slovakia on the Velká Javorina Hill, the highest hill of the Malé Karpaty Mts.. All these three stations are equipped with the three-component wide-range sensor STS-2 and the registering apparatus Quanterra. The signal registered by these stations is also transmitted to the NDC in Brno where it is processed together with data from the VRAC station. Recent seismic activity has been monitored by seismological stations of the Institute of Physics of the Earth, Faculty of Sciences, Masaryk University Brno (IPE) since 1992 (see Encl.No.2 - Fig.1). The weak tectonic events were recorded in Moravia and Silesia and were published step by step (Havífi, Pazdírková 1995; Havífi, Skácelová 1996; Skácelová, D., Skácelová, Z., Havífi 1997; Skácelová, Skácel and Havífi 1998). Seismic activity in the north eastern part of the Bohemian Massif has been monitored by other institutions - Technical University of Ostrava and Institute of Geonics of the Academy of Sciences of the Czech Republic. Research results were published in the geophysical journal and contribute to the geological interpretation of registered earthquakes (Kaláb et al., 1995, 1996; Holub, Müller 1997). The mobile digital seismological short-period station MUTC in Mutkov in the southeastern margin of the Nízk˘ Jeseník Mts. was put into operation in October 1996. This station is equipped with the three-component sensor MARK and the Lennartz 5800 registering apparatus. 16 “Exploration Geophysics, Remote Sensing and Environment“ V. 2. (1998) and depths. Epicentres of earthquakes are concentrated into two areas approximately 5 km apart (about 2 km from the R˘Ïovi‰tû village) and have a strongly swarm-like character. On 27th March 1998 the MUTC station registered 18 events during 1.5 hour, with identical waveforms. The maximum computed local magnitudo ML was 1.4. In February 1998 two events with opposite direction of the first motion were recorded in the same area. It can be assumed that the mechanism of the movement is changing during seismic activity. Besides seismological stations operated by the IPE Brno there are stations operated by the Technical University of Ostrava - the OKC station in Ostrava, and by the Institute of Geonics of the Academy of Sciences of the Czech Republic the SPF array near Fren‰tát, the ZHL station in Zlaté Hory, and HRC in Hradec u Opavy, situated in this region. SEISMIC ACTIVITY In the period from October 1994 to September 1998 a total of 131 microearthquakes (local magnitudo ML 2.0) were recorded in the northeastern margin of the Bohemian Massif at stations of the IPE Brno. Twenty of them could be localised by the HYPO3D program that is based on the block velocity model of the Earth Crust. The main condition for computation was to know at least five arrival times of wave phases going through the Upper Crust registered by at least three stations. A block velocity model compiled in the IPE Brno from the results of refraction seismic measurements and geological and geophysical data (Dvofiák, Firbas and Skácelová 1993). This model characterises wider surroundings of the profile from the Culm of the Nízk˘ Jeseník Mts. into the Neogene sediments of the Carpathian Foredeep (area of the Moravian Gateway) and Outer Flysch. Data from the co-operating organisations were used to localise some stronger events. Close to this epicentral area the Klepáãov fault, an occurrence of neovolcanics, and sources of mineral waters are described. Moravian Gateway and the Host˘n Hills (D) Seismic activity in these areas has been observed only recently. On 9th August 1994 an earthquake swarm of 9 events (local magnitudo ML 1.5) was registered in the area of Moravian Gateway. The strongest event of this swarm was also registered by the SPF array. Due to the insufficient number of stations, computations localised the epicentres only approximately to the vicinity of Hranice na Moravû. On 1st May 1997 a relatively strong earthquake was recorded and localised into the Host˘n Hills area. Stations of the SPF array contributed to a more accurate localisation and to the computation of the depth of this event, that was approximately 25 km. Registered earthquakes indicated several active areas in the northeastern margin of the Bohemian Massif. The Opava region (A) We can suppose that seismic activity in both these areas is related to faults in the underlying rocks of Outer Flysch (it cas been confirmed by the depth of the hypocentre), consequently to the rocks of the Bohemian Massif. This region is known for earthquake manifestations from historical records. Also a previous geological survey indicated recent seismotectonic movements and their significance for fault declines in the sedimentary filling of the basin. The latest strong earthquakes of a swarm-like character were registered in August 1993 in the close vicinity of the city of Opava. Only weak quakes have been registered since then, mainly in the southern margin of the Opava sedimentary basin in the vicinity of the Nízk˘ Jeseník fault. Margin of the Haná area (E) Stations of the IPE Brno have registered a weak seismic activity also in the marginal areas of the sedimentary filling of the Haná basin. Isolated earthquakes were registered and localised to the areas of Uniãov,·ternberk, Prostûjov and Konice (local magnitudo ML 0.1). The Odra Hills (B) Weak earthquakes were registered in this area in 1986 during detailed seismic monitoring that was carried out by the Geofyzika Brno company. Since October 1993 isolated weak earthquakes have been registered by stations of the IPE Brno in this area. They can be identified with a particular fault system only with difficulty. The strongest of them (local magnitudo ML=1.6) was registered on 28th February 1997 and it was localised into the area of Jánské Koupele. We suppose that these earthquakes have been connected with the marginal faults of the Haná basin - Bu‰ín and Temenice faults and the Konice-Nectava fault zone. Northern part of Boskovice furrow (F) No seismic activity had been recorded in this area until 1993. The first seismic event was recorded and localised to the northern margin of the Boskovice furrow in October 1993 after the VRAC station had been installed. This earthquake was also registered by other seismic stations in the Czech Republic (PRU, KHC - seismic stations operated by the Geophysical Institute of the Czech Academy of Sciences). By the end of 1998 six earthquakes were localised to this area. Epicentres of these earthquakes are concentrated into three areas - the northeastern margin of the Boskovice furrow (Jevíãko), the northwestern margin of the Boskovice furrow Nízk˘ Jeseník - R˘Ïovi‰tû (C) Earthquakes originated in this area were for the first time observed in 1993 after launching the MORC station. As frequent occurrences were recorded, and some historical sources mentioned occurrences of earthquakes in the ·ternberk area, the MUTC mobile seismic station was installed north of ·ternberk in 1996. This station significantly contributed to the accurate computation of their epicentres 17 “Exploration Geophysics, Remote Sensing and Environment“ LEGEND - to the Enclosures No.1/No.6 V. 2. (1998) (Thickened and deep buried column started to ascend isostatically during the Carboniferous - after release of orogenic control of this stacking). Encl.No.1: Fig.1 Geological schema of the Western Bohemia region. Fig.9 Thermal alterations of tiny organic fossils conodonts. (The darker color of the conodont, the higher maximum temperature during the burial history - with little corrections for other processes. Conodonts were formed by francolite with a low content of organic matter, carbonate, clay minerals and other mineral accessories). Encl.No.2: Fig.1 Geological map of the eastern part of the Bohemian Massif with epicentres ofthe microearthquakes. Encl.No.3: Fig.1 Main tectonic outlines of the East Sudetes (Silesicum). (by Skácel 1998) Encl.No.5: Fig.6 Diagrams illustrating paleogeographical concepts by authorities of the discipline (our opinion is expressed in the lower right corner of the picture). Encl.No.4: Fig.1 Typical microimage of Upper Devonian limestone from Mokrá, in passing light on the left, cathodeluminiscence image on the right. Fig.8 Pole projections based on the Early and Middle Devonian sites (groups of the sampled sections and traverses), Moravia and central Bohemia (Barrandian). Explanations: 1 - Kacak Event, Eifelian-Givetian, U Dubu sedmi bratfií; 2 - Middle/Late Eifelian, Hostim in Hostim - Srbsko roadcut; 3 - Emsian-Eifelian, Pragstav quarry near Holynû; 4 - Praghian, Bránická skála, Prague; 17 - Givetian, Josefov junction, Near Adamov; 18 - Eifelian, âelechovice na Hané, near Prostûjov. Fig.2 Diagenesis of Upper Devonian limestones in Mokrá. Fig.3 Paleotectonic rotation and Variscan magnetic overprint on Moravian Devonian limestones, illustrated by positions of paleomagnetic poles. Explanations: Devonian paleomagnetic poles calculated from the C-component are on the globe on the left (violet); poles calculated from the B-component of Carboniferous/Permian overprint are on the right (red). Thin lines illustrate model rotation paths of poles conditioned by the horizontal component of tectonic rotation of a rock segment with paleomagnetic inclination I, from +5° to -35°, after 5° (as if by turning a sample round vertical axis we drew a circle on the globe. Empty circles on this path correspond to the difference in declination (step) ∆ D 20° . The path of apparent movement of poles (APWP) from the Devonian to the Triassic, based on the stable (undeformed by Variscan orogeny) part of the Europe is illustrated by a thick line with points representing approximate mean positions for parts of units, e.g. Devonian D1, D2, D3, etc. (Krs and Pruner, 1995). The sites belong to diferent terranes and tectonic segments (slices and nappes), where horizontal component of the Variscan tectonic rotation is very strong. The Devonian inclinations about -25 degree imply palaeogeographical positions about 10 degree South, or even more southerly towards 20’s latitudes. Generally, the Barrandian latitudes of these times were not higher than in Moravia. Fig.7 Sequence of seven generations of faults, found by the method younger intersects the older on outcrops and in geological map, discussed in chapter Tectonics under nos.1-7. Explanations: 1 - segments with ruptures according to tectonic map (geological atlas); 2 - segments with tectonic predestinations of river beds (geological atlas); 3 - segments with ruptures according to geodetic measurements (Demek, Loyda 1984); 4 - paths; 5 circles: localities of markets; 6 - triangles: occurrences of ancient coins in Moravia. Encl.No.6: Fig.1 Network of paths in the Czech Republic (Kvût 1997 - originally worked out with ¤ehák, S.) with identical directions of earth crust ruptures, a map of the Czech Republic with the network of paths (Kvût 1997), occurrences of ancient coins (Sejbal 1979) and localities of 12 and 13 century markets (Kejfi 1987). Fig.8 Visualization of the area where a thick stack of nappes (thickening of crust) originated during the Visean/Namurian times. 18 „Exploration Geophysics, Remote Sensing and Environment“ V. 2. (1998) Fog. 2 : Schema of the occurrences of the Tertiary/Quaternary volcanics, the springs of carbonated mineral water and the epicentres of the micro-earthquakes. 19 “Exploration Geophysics, Remote Sensing and Environment“ V. 2. (1998) were revealed in the north-eastern part of the Bohemian Massif also by an analysis of repeated geodetic measurements (Vyskoãil 1991). Very important is the recent extension detected by the analysis of repeated geodetic measurements in the region of the Western Carpathian Flysh Belt in southeastern Moravia (Vyskoãil 1991; Vyskoãil, Zeman 1980). (Svitavy) and the area north of the city of Poliãka. The local magnitudo ML of the strongest event was 1.9, the latest event was registered on 25th November 1998. It cannot be explicitly stated which fault system is this seismic activity connected to. A whole range of faults passes through this area - in the NW-SE direction the Konice Nectava fault zone and its continuation to the Cretaceous platform cover, and the NS trending faults limited by the sedimentary filling of the Boskovice furrow. The epicentres of microearthquakes occur in the eastern part of the Bohemian Massif mainly near the major NW - SE trending fault structures (the Bu‰ín fault, the Kletná fault, the Klepáãov fault, the Temenice fault, the Konice-Nectava fault system, etc.- see for instance Skácelová, Skácel and Havífi 1998; Skácelová D., Skácelová Z. and Havífi 1997). Microearthquakes are often detected near crossings of the faults with significant faults of other systems. This can indicate the affinity of the seismo-tectonic activity to the movement along NW-SE trending faults. Králick˘ SnûÏník Massif (G) No earthquake has been recorded in this area. A tectonic event with local magnitudo ML = 1.4 was registered by a station of IPE Brno on 20th December 1997 and with the help of other stations of the National Seismological Network of the Czech Republic (PRU, KHC seismic stations operated by the Geophysical Institute of the Czech Academy of Sciences) localised to the vicinity of Králick˘ SnûÏník. The Kletná fault passes in the NW-SE direction from Poland to the Králick˘ SnûÏník Massif where it is followed up by the Klepáãov fault. The NW-SE striking faults may be very important tectonic structures for the Pliocene/Quaternary tectonic activity. In the Haná area the block of the Hornomoravsk˘ úval decreased along these faults during the Pliocene/Pleistocene period (RÛÏiãka 1973; Zeman et al., 1980). The overprint of the NW-SE striking faults into the Western Carpathian Flysh Belt confirms the impact of their Saxonian tectonic activity (Buday et al., 1995). The Pliocene/Pleistocene volcanic activity in the Jeseníky region is also connected with NW-SE trending faults (for instance Kumpera 1994; Pfiichystal 1993). The major NW-SE trending faults often create expressive morphological slopes. The height of the fault slope of the Marginal Sudetic fault is up to 250 m in the Rychlebské hory Mts (Ivan 1998). MICRO-EARTHQUAKES IN RELATION TO THE TECTONIC AND THE RECENT TECTONIC ACTIVITY The recent seismotectonic activity is concentrated in the north-eastern part of the eastern margin of the Bohemian Massif, especially in the Haná area (the block of the Hornomoravsk˘ úval) and in the Nízk˘ Jeseník area. Seismological stations operated by IPE Brno have detected hardly any tectonic events that could be connected with faults in the eastern part of the Bohemian Massif southwards of the Konice-Nectava fault system. However, the possible recent weak seismo-tectonic activity along the eastern marginal fault of the Boskovice furrow has not been elucidated yet. Figdor and Scheidegger (1977) informed about the tectonic events near the Diendorf fault, a southern continuation of the eastern marginal fault of the Boskovice furrow. Seismological stations operated by IPE Brno have detected several micro-earthquakes near the crossing of this eastern marginal fault and the Konice-Nectava fault system (Havífi, Pazdírková 1995). That is why the weak seismotectonic activity along the eastern marginal fault of the Boskovice furrow could be expected. The seismo-tectonic activity is also connected with some E-W striking faults. Kumpera (1994) supposed that the microearthquakes occurring south of Opava were closely related to the recent tectonic activity of the E-W trending marginal fault of the Jeseníky Mts. This fault limits the Neogene and the Quaternary sediments of the Opava basin and is connected with the Neogene subsidence of the Opava basin. Also the tectonic event of the 1st May 1997 (Havífi, Skácelová 1998) localised in the SE of Vala‰ské Mezifiíãí near the crossing of the E-W striking RoÏnov fault and the NS striking marginal fault of the Upper Silesian Coal Basin could be connected with tectonic activity of the E-W trending RoÏnov fault under the Western Carpathian flysh nappes. CONCLUSION The only weak seismo-tectonic activity was observed in the eastern margin of the Bohemian Massif (Moravia and Silesia) by stations of IPE Brno. The epicentres of microearthquakes occur near of the significant NW-SE trending fault structures and near some significant EW striking faults. This can indicate the affinity of the seismotectonic activity to the movement along NW-SE striking faults. These faults seem to be very important tectonic structures for the Pliocene/Quaternary tectonic activity. The occurrences of micro-earthquakes show the continuation of their tectonic activity up to the Recent. Another evidence of the Pliocene/Quaternary tectonic activity is also found mainly in the northeastern part of the eastern margin of the Bohemian Massif. From the Nízk˘ Jeseník area the products of Pliocene/Pleistocene volcanic activity are known (Barth 1977; Pfiichystal 1993). Also the springs of the carbonated mineral water are found only in the north-eastern part of the eastern margin of the Bohemian Massif (Fig.2). Thus the space distribution of the epicentres of the microearthquakes correspond very well to the occurrences of the Pliocene/Pleistocene volcanics and the springs of the carbonated mineral water in the eastern part of the Bohemian Massif. Signifcant recent crustal movements 20 “Exploration Geophysics, Remote Sensing and Environment“ V. 2. (1998) Koláãek, F. (1921): Seznam otfiesÛ pozorovan˘ch na pÛdû republiky âeskoslovenské. Spisy pfiírodovûd. fak. Masaryk. Univ., 7, pp. 3-11, Brno. Kumpera, O. (1994): Geologická stavba opavské neogenní pánve a její vztah k opavské seismické oblasti. Sborník referátÛ “InÏen˘rská seismologie“, pp. 95-101, Ostrava. Pfiichystal, A. (1993): Vulkanismus v geologické historii Moravy a Slezska od paleozoika do kvartéru. In Pfiichystal, A., Obstová, V., Suk M. (eds.): Geologie Moravy a Slezska, pp. 59-70, Brno. Reme‰, M. (1902): Zemûtfiesení na Moravû pozorovaná. Vûst. klubu pfiírodovûd. v Prostûjovû za rok 1902, 5, pp. 3-11. RÛÏiãka, M. (1973): Fluviální sedimenty fieky Moravy v okolí Olomouce. Sbor. geol. vûd, Antropozoikum, pp. 7-43, Praha. Schenková, Z., Kárník, V., Schenk, V. (1980): Map of epicentres for Czechoslovakia and adjacent area.In Atlas of seismological maps, Central and Eastern Europe, the Geoph.Inst. of the Czechosl. Academy of Scienc., Prague. Skácelová, D., Skácelová, Z., Havífi, J. (1997): Earthquakes in the northeastern part of the Bohemian massif recorded by the MORC station during the period October 1994 - March 1995. Vûst. âes. geol. úst., 72, 1, pp. 49-53, Praha. Skácelová, Z. (1996): Zemûtfiesení na severov˘chodním okraji âeského masívu registrovaná stanicemi MORC a VRAC. In Kaláb ed.: Anal˘za dat v seismologii a inÏen˘rské geofyzice, pp. 72-82, Ostrava. Skácelová, Z. (1997): Nové poznatky z mûfiení seismické aktivity na severov˘chodním okraji âeského masívu. In Kaláb ed.: V˘sledky nov˘ch studií v seismologii a inÏen˘rské geofyzice, Ostrava. Skácelová, Z., Havífi, J. (1995): Seismotektonická anal˘za. In: Sborník referátÛ mezinárodní vûdecké konference u pfiíleÏitosti 50. v˘roãí pÛsobení V·B v Ostravû, Sekce 3, Geologie, pp. 174177, Ostrava. Skácelová, Z., Skácel, J., Havífi, J. (1998): Nejnovûj‰í poznatky o seismicitû Moravy a Slezska. In. Kaláb Z. (ed.): Souãasné smûry v seismologii a inÏen˘rské geofyzice (regionální konference s mezinárodní úãastí), sborník referátÛ, 1.díl, pp. 4048, Ostrava. Vyskoãil, P. (1991): Recentní pohyby a deformace zemského povrchu na území âeské republiky a jejich praktické dÛsledky. Geodetick˘ a kartografick˘ obzor, 37/79, 1, 6-13. Vyskoãil, P., Zeman, A. (1980): Problematika a dosavadní v˘sledky studia recentních pohybÛ zemského povrchu na styku âeského masívu a Karpat. âas. Mineral. Geol., 25, 4, pp. 389407, Praha. Zeman, A., Havlíãek, P., Minafiíková, D., RÛÏiãka, M., Fejfar, O. (1980): Kvartérní sedimenty stfiední Moravy. Sbor. geol. vûd, Antropozoikum, pp. 37-85, Praha. REFERENCES Barth, V. (1977): âediãové vulkány stfiední ãásti Nízkého Jeseníku. âas. Mineral. Geol., 22, 3, 279-291. Praha. Buday, T., ëurica, D., Opletal, M., ·ebesta J. (1995): V˘znam bûlského a klepáãovského zlomového systému a jeho pokraãování do Karpat. Uhlí, Rudy, Geologick˘ prÛzkum, 9, pp. 275-282. Praha. Dvofiák, V., Firbas, P., Skácelová, Z. (1993): Velocity distribution modelling on building site of the nuclear power plant of North Moravia - A case history. Applied geophysics, UÏitá geofyzika, 25, pp. 49-66. Figdor, H., Scheidegger, A. E. (1977): Geophysikalishe Untersuchungen an der Diendorfer Störung. Verh. Geol. B.- A., 3, pp. 243-270. Wien. Havífi, J., Pazdírková, J. (1995): Série otfiesÛ z okolí Jevíãka (leden 1993) a tektonické otfiesy Nízkého Jeseníku (listopad a prosinec 1994) - (Series of earthquakes from surroundings of Jevíãko (January 1993) and tectonic tremors from the Nízk˘ Jeseník Highland (November and December 1994)). Geol. v˘zk. Mor.Slez. v r. 1994, p. 110. Brno. Havífi, J., Skácelová, Z. (1996): Tektonické otfiesy na v˘chodním okraji âeského masívu (Tectonic earthquakes at the eastern part of the Bohemian Massif). Geol. v˘zk. Mor. Slez. v r. 1995, pp. 4-8. Brno. Havífi, J., Skácelová, Z. (1998): Tektonické mikro-zemûtfiesení od Vala‰ského Mezifiíãí z 1.5.1997 (Tectonic micro-earthquake from Vala‰ské Mezifiíãí, 1.5.1997). Geol. v˘zk. Mor. Slez. v r. 1997, pp.100-102,Brno. Havífi, J., Skácelová, Z., S˘korová, Z. (1997): Recentní tektonické pohyby v jihozápadní ãásti Nízkého Jeseníku (Recent tectonic movements in southwestern part of the Nízk˘ Jeseník Mts.). Geol. v˘zk. Mor. Slez. v r. 1996, 6 - 7. Brno. Holub, K., Müller, K. (1997): Seismická aktivita zlomÛ na severov˘chodní Moravû. In Kaláb ed.: V˘sledky nov˘ch studií v seismologii a inÏen˘rské geofyzice. Ostrava1997. Ivan, A. (1998): Morfotektonika okrajového sudetského zlomu v oblasti styku lugika a silezika v Rychlebsk˘ch horách. Geol. v˘zk. Mor. Slez. v r. 1997, 4-5, Brno. Kaláb, Z., Kumpera, O., Müller, K. (1995): Seismická aktivita a geofyzikální obraz severní ãásti moravsko-slezské oblasti. In Kaláb ed.: Nové poznatky v seismologii a inÏen˘rské geofyzice, Ostrava. Kaláb, Z., Kumpera, O., Müller, K. (1996): Macroseismic Fields in the Jeseníky area. Exploration Geophysics Remote Sensing and Environment (EGRSE), III.1/96, pp. 14-8. 21