Archaeoseismology and Palaeoseismology in the Alpine ... - Tierra

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macroseismic magnitude M M=3‐4.9. However, these magnitudes are not considered to be enough for creating a relief (cf. McCalpin 1996). Thus, the presented research using near‐fault investigation in artificial trenches in the Czech portion of the SMF was carried out in order to discover probable pre‐historic faulting responsible for the mountain front morphology as well as to reveal the kinematics of the fault. In order to select a suitable site for trenching, geomorphological investigation, analysis of the digital elevation model, and geophysical sounding (multi‐ electrode method, GPR) were carried out. The results of trenching in two localities (Vlčice and Bílá Voda) are presented here. Fig. 2: Strike‐slip fault zone with a feature of flower structure documented in the trench in Vlčice site. A – older Miocene unit, B – younger Miocene unit, C ‐ deformation zone, D ‐ early Holocene colluvium. Note the dragged B unit layers. The trenching across the SMF at the first locality Vlčice on the N‐S trending mountain front revealed succession of sedimentary units disturbed by tectonic features. The trench exposed crystalline rocks, three units of early to mid Miocene fluvial to limnic sediments with organic‐rich beds (with graphite), Pleistocene alluvial fan deposits, and three sequences of Holocene colluvium. Several faults were documented: reverse faults (strike 160°, dip 40‐70° to SW) displacing crystallinics over Miocene deposits, a subvertical deformation structure (probably strike‐slip) within the Miocene sediments (strike 35°, dip 75° ESE; Fig. 2), and minor normal faults within the youngest Miocene unit (strike 145°, 45° to NE). Moreover, the three Miocene sedimentary members, positioned vertically next to each other, were probably dragged by the reverse fault. To determine the age of the identified deformations variously dated sediments were used. The dating included: known age of mid Miocene deposits, radiocarbon dating of charcoal and paleosols, and supposed Late Pleistocene age of the last gelifluction. Time constraint of the identified fault movements is given in Table 1. Movements disturbing Neogene deposits and pre‐dating last gelifluction involve the reverse faulting that displaced crystalline rocks over the Miocene deposits, and horizontal movements. The younger movements occurred by reverse and normal faults. One of the younger reverse fault within the crystalline rocks probably created a coseismic relief step, which is concealed by early Holocene colluvial deposits (10,940±140 cal. yrs BP). This step was documented 0.6 m high at the distance of 1.3 m and was covered by a 1 st INQUA‐IGCP‐567 International Workshop on Earthquake Archaeology and Palaeoseismology 150 colluvial wedge‐like form. As the step must have been seen on the surface before the deposition of the Holocene sediments and at the same time it is not affected by Late Pleistocene gelifluction, the movements occurred probably on the boundary Pleistocene/Holocene. The youngest movements probably occurred in the lowest part of the slope and were related to normal faults. The faults cut the Miocene sediments and divide two area with diverse erosion/depositional regime. Moreover, this zone coincides with spring area and low resistivity zone shown by the geophysical sounding. This normal faulting predates the soil sediment (410±80 cal. yrs BP) buried by the youngest colluvium. Trenching at the second locality Bílá Voda was carried out across NW‐SE trending mountain front. The exposure revealed strike‐slip fault zone (striking 135°‐150°) dividing Paleozoic crystalline rock and Late Pleistocene colluvial deposits derived from the fault zone (Fig. 3). The deposits overlay Miocene sediments, which are warped. The fault has a flower structure character and shows several repeated movements. Kinematic indicators within the older structures show a sinistral component. However, the sense of the youngest movements will be able to recognize based on further trenching in this locality, since the recent stresses inferred from GPS and micro‐ displacements measuring are not unequivocal (see Badura et al., 2007, Štěpančíková et al., 2008). Table 1: Time constraint of faulting history within the SMF identified at the trenching site Vlčice. The ages are based on the age of deformed sediments, radiocarbon dating of charcoals, and paleosols covering the deformed sediments. type of deformation time limits of movements maximum minimum reverse faulting 15 Ma yrs BP 15‐11 ka BP horizontal movements 15 Ma yrs BP 15‐11 ka BP reverse faulting 15‐11ka yrs BP 10,940 ± 140 cal. yrs BP latest normal 10,940 ± 140 cal 410 ± 80 calBP faulting BP Dating of movements is based mainly on the relative age of the Late Pleistocene fault‐related colluvial deposits. Besides clasts of tectonic breccia, they include pebbles of eratic material coming from glacial deposits, whereas the last continental glacier reached the study area in Elsterian 2 (400‐460 ka). Moreover, the Pleistocene deposits, fault zone, and crystalline rocks are covered by geliflucted layers of all the involved rock types and then by the youngest Holocene colluvial deposits (800±50 cal. yrs BP). Younger individual faults of the fault zone penetrate the Late Pleistocene deposits but they are concealed by the geliflucted layers. Since the coarse‐grained fault‐related deposits are quite homogeneous at the whole thickness (maximum confirmed 3.5m), no individual faulting events could be recognized. The youngest movements (probably horizontal with some vertical component) displaced even the geliflucted layers, while the vertical displacement made up around 35 cm (Fig. 4). These displaced layers are concealed by the recent Holocene colluvium. To estimate the magnitude of this last event, further trenching focused on horizontal offset identification will be necessary.
1 st INQUA‐IGCP‐567 International Workshop on Earthquake Archaeology and Palaeoseismology Fig. 3: Simplified log of the trench in Bílá Voda site with geological information. Geliflucted layers of crystalline rocks covering the crystalline bedrock and Pleistocene sediments are depicted in the same colour as their maternal rocks. To conclude: due to petrological, sedimentological, and structural analyses, along with utilization of dating techniques, at least four movement phases from Mid Miocene to Holocene within the SMF zone were documented in the trenches. As during Pleistocene the area has been repeatedly reached by a continental ice‐ sheet, a record of Pleistocene tectonic activity is poorly preserved in the studied site and only wide time constraints can be proposed. However, Late Quaternary tectonic activity was revealed and even a prehistoric earthquake suggested. The trenching technique has appeared to be a powerful tool of near‐fault investigation since the study area is situated in a well‐vegetated region with moderate climate and therefore devoid of fault outcrops. Moreover, the study area is situated in an intraplate region with a low displacement rate; consequently, higher erosion rate exceeds displacement rate, which does not favor the preservation of fault scarps. Fig.4: Vertical displacement (around 35cm) of Late Pleistocene geliflucted layers probably by strike‐slip faults with a reverse component. Acknowledgements: The research was supported by the Grant Agency of the Czech Republic No. 205/06/1828, by the Slovak Research and Development Agency under the contract No. APVV‐0158‐06 and has been elaborated within the Institute Research Plan of the Institute of Rock Structure and Mechanics, Academy of Sciences of the Czech Republic, No. AVOZ30460519. 151 References Badura, J., Zuchiewicz, W., Górecki, A., Sroka, W., Przybylski, B., Zyszkowska, M. (2003): Morphotectonic properties of the Sudetic Marginal Fault, SW Poland. Acta Montana, Series A, 24 (131), 21‐49. Badura, J., Zuchiewicz, W., Štěpančíková, P., Przybylski, B., Kontny, B., Cacoń, S. (2007): The Sudetic Marginal Fault: a young morphotectonic feature at the NE margin of the Bohemian Massif, Central Europe. Acta Geodyn. Geomater., 4: 4 (148), 1‐23. Dyjor, S. (1995): Young Quaternary and recent crustal movements in Lower Silesia, SW Poland. Folia Quaternaria, 66, 51‐58. Guterch, B., Lewandowska‐Marciniak, H. (2002): Seismicity and seismic hazard in Poland. Folia Quaternaria, 73, 85‐99. Ivan, A. (1997): Topography of the Marginal Sudetic Fault in the Rychlebské hory Mts. and geomorphological aspects of epiplatform orogenesis in the NE part of the Bohemian Massif. Moravian Geographical Reports, Brno, 5 (1), 3‐17. Krzyszkowski, D., Bowman, D. (1998): Neotectonic Deformation of Pleistocene Deposits Along the Sudetic Marginal Fault, Southwestern Poland. Earth Surface Processes and Landforms, 22 (6), 545‐562. Krzyszkowski, D., Pijet, E. (1993): Morphological effects of Pleistocene fault activity in the Sowie Mts., southwestern Poland. Zeitschr. Geomorph., N.F., Suppl.‐Bd. 94, 243‐259. Krzyszkowski, D., Migoń, P., Sroka, W. (1995): Neotectonic Quaternary history of the Sudetic Marginal fault, SW Poland, Folia Quaternaria, 66, 73‐98. Krzyszkowski, D., Przybylski, B., Badura, J. (2000): The role of neotectonics and glaciation on terrace formation along the Nysa Kłodzka River in the Sudeten Mountains (southwestern Poland). Geomorphology, 33, 149‐166. Mastalerz, K., Wojewoda, J. (1993): Alluvial‐fan sedimentation along an active strike‐slip fault: Plio‐Pleistocene Pre‐Kaczawa fan, SW Poland. Spec. Publs. Int. Assoc. Sedimen. ,17, 293‐304. McCalpin, J. ed. (1996): Paleoseismology. Academic press, 588 pp. Migoń, P. (1993): Geomorphological characteristics of mature fault‐generated range fronts, Sudetes Mts., Southwestern Poland. Zeitschr.Geomorph. N. F., Suppl.‐Bd. 94, 223‐241. Oberc, J., Dyjor, S. (1969): Uskok sudecki brzeżny. Biul. Inst. Geol., 236, 41‐142. Oberc, J. (1977): The Late Alpine Epoch in south‐west Poland. In: W. Pozaryski (ed.), Geology of Poland, IV, Tectonics, Wydawn. Geol., Warszawa, 451‐475. Štěpančíková, P., Stemberk, J., Vilímek, V., Košťák, B. (2008): Neotectonic development of drainage networks in the East Sudeten Mountains and monitoring of recent fault displacements (Czech Republic). Special Issue on: Impact of Active econics and Uplift on Fluvial Landscapes and River Valley Development. Geomorphology, 102 (1), 68‐80.
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Abstracts Volume Archaeoseismology
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Edita e imprime: Sección de Public
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1 st INQUA‐IGCP‐567 Internation
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the importance of performing absolu
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indicative of strike‐slip faultin
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DISCUSSION Based on detailed field
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Table 1: Source parameters used in
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elations. However, the attenuation
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mostly concentrated on the DST in I
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continuous support. N. Shalev, G. G
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The tumulus initial morphology show
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our understanding and prediction of
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spans, with a threefold increase fr
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Nevertheless the lack of research,
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earthquake. In uncertain cases, as
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The site reconnaissance successfull
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Table 1: Surface faulting extent re
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The graben has a markedly asymmetri
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are a valuable addition to the rout
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to 400 m) the calculated values for
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RISK ANALYSIS The created hazard ma
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290 m water depth the basin accumul
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CONCLUSIONS From the palaeostress a
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Fig. 2: Geological map of the study
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however, the massive 1995 earthquak
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mapped on the slopes above Qiryat
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interpreted as either an expression
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The Shepran Cave is located on the
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properties. The mean value of speci
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excavated a deep trench, thus provi
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Fig. 8: Seismic ground shaking may
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Page 103 and 104: CONCLUDING REMARKS The exposed exam
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Page 107 and 108: It is possible that a portion of th
Page 109 and 110: In addition, the Database of histor
Page 111 and 112: were published by IGME (1983) and E
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Page 115 and 116: The city collapsed and it was aband
Page 119 and 120: Fig. 4: Slipped lintel in a window
Page 121 and 122: to overcome shear resistance and in
Page 123 and 124: Newmark, N.M. (1965). Effects of ea
Page 125 and 126: associated with various tsunamis (<
Page 129 and 130: this method, the magnitude of the e
Page 133 and 134: etween pieces. Fragments have not f
Page 137 and 138: on the exact date of the earthquake
Page 139 and 140: THE ARCHAEOLOGICAL ZONE COLOGNE Aft
Page 143 and 144: affecting the Alcázar was about 50
Page 147 and 148: archaeoseismology could instead bec
Page 149 and 150: In the area later occupied by Vilni
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Page 155 and 156: Fig. 2: Assemblage of landforms ass
Page 157 and 158: Fig. 8: Data and regression for mag
Page 159 and 160: Fig. 3: Relationships among magnitu
Page 161 and 162: CONCLUSIONS 1. Spatial distribution
Page 163 and 164: The stratigraphic sequence (Fig. 4)
Page 165 and 166: especially in the zones of hanging
Page 169 and 170: interpretations are based on relati
Page 173 and 174: Fig. 5: Gray‐scale value laser im
Page 177 and 178: (~40 cm), F‐ rotated building str
Page 179 and 180: Index 1 st INQUA‐IGCP‐567 Inter
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Archaeoseismology and Palaeoseismology in the Alpine ... - Tierra

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