Archaeoseismology and Palaeoseismology in the Alpine ... - Tierra

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1 st INQUA‐IGCP‐567 International Workshop on Earthquake Archaeology and Palaeoseismology UPPER PLEISTOCENE TECTONIC ACTIVITY IN THE CENTRAL PYRENEES RANGE (NAVARRA, N SPAIN) J.M. Insua Arévalo (1) and J. García‐Mayordomo (2) (1) Departamento de Geodinámica. Universidad Complutense de Madrid. c/ José Antonio Novais, 2. 28040‐Madrid, SPAIN. insuarev@geo.ucm.es (2) Instituto Geológico y Minero de España. Área de Investigación en Peligrosidad y Riesgos Geológicos. C/La Calera, 1 (Tres Cantos). 28760‐ Madrid. SPAIN. julian.garcia@igme.es Abstract: This work analyses some geomorphologic aspects of fluvial terraces relating to a fault‐related folding which is rising up the Sierra of Leyre in the central part of the Pyrenees. The terraces have been dated by thermoluminiscence (TL) method as Upper Pleistocene (
Fig. 2: Geological map of the study area (Gobierno de Navarra, 1997a). The white and orange dots show the location of the TL samples. OBSERVED DEFORMATIONS We have analyzed the geological and geomorphological maps (Gobierno de Navarra, 1997a, b), as well as the digital terrain model, and stereoscopic pairs of aerial photos, identifying six terraces at the Irati River: T1 (+40m), T2 (+36m), T3 (+30m), T4 (+24m), T5 (+10m) and T6 (+5m). Several topographic profiles have been made in order to examine possible deformation relating with the tectonic activity. The profile shown in Fig. 3 runs along the highest terraces T1 (+40m) at the right side of the Irati River to the north of the anticline of the sierra. The slope of the terrace surface has 0.2º. We have identified a deposit of fluvial terrace located just over the folded sierra, at the place of Biezcas, which is lifted with respect to the trend of the slight slope of the others. Fig. 3: Topographic profile along the terraces T1 (+40m) at the right side of the Irati River to the north of the sierra. The terrace located just over the folded sierra is lifted with respect to the trend of the slight slope (0.2º) of the others. This fact could be related to the grow of the anticline that built up the sierra. The northern flank of the fold lifts the terrace deposit up to 43m over the thalweg of the river, 3m higher than the highest terrace identifying at the area. Unfortunately, the farming works has modified remarkably the original deposit loosing the initial slope of the terrace surface, and no tilting could be measurement. Nevertheless, attending to the trend of the slope of the surface of the highest terrace T1 (+40m) to the North, the terrace of Biezcas is lifted 4 m as a minimum. At the other side of the sierra, a second topographic profile runs along different terraces (Fig. 4). The profile has a stepped shape for comparing purposes. The first segment of the profile runs along the terrace T1 (+40m) 1 st INQUA‐IGCP‐567 International Workshop on Earthquake Archaeology and Palaeoseismology 61 showing an angle of slope of 2º to the ESE. This slope value is remarkably higher than that of the terrace at the other side of the sierra. The segment running through the following terraces seems to be quite flat again. In this case it is difficult to fit the deformation to the grow of the anticline of the sierra because of the oblique orientation of the slope. In any case, such a slope in a terrace have to be related with a tectonic origin, like a minor fault which accommodate the local deformation, in absence of other possible mechanisms like halocinetic processes. Fig. 4: Topographic profile along the terraces (+40m) of the Irati River to the south of the sierra. The terrace located at the right side is tilted up to 2º. Compare the slope with that of the terraces located to the north of the sierra (See Fig.3). THERMOLUMINISCENDE DATING In order to determine the age of the deformation found at the study area, eight samples were collected at different units for dating by Thermoluminiscence procedure (TL) (see Fig. 1 for location). Not only the terraces involved in the deformation where considered, but also other levels and coluvial material were taking into account to acquire a better understanding of the evolution of the structure and the landscape. The TL dating procedure considers the light exposure occurring during transport of the sediment grains in a dispersed state, prior to their deposition (Forman, 1989). The ages obtained by this method are presented in the Fig. 5. Fig. 5: TL age of the samples (white dot) with interval of error. The samples are grouped by geological unit and put into order from older to younger
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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
Page 11 and 12: indicative of strike‐slip faultin
Page 13 and 14: DISCUSSION Based on detailed field
Page 15 and 16: Table 1: Source parameters used in
Page 17 and 18: elations. However, the attenuation
Page 19 and 20: mostly concentrated on the DST in I
Page 21 and 22: continuous support. N. Shalev, G. G
Page 23 and 24: The tumulus initial morphology show
Page 25 and 26: 1 st INQUA‐IGCP‐567 Internation
Page 27 and 28: our understanding and prediction of
Page 29 and 30: spans, with a threefold increase fr
Page 31 and 32: Nevertheless the lack of research,
Page 33 and 34: earthquake. In uncertain cases, as
Page 35 and 36: The site reconnaissance successfull
Page 43 and 44: Table 1: Surface faulting extent re
Page 47 and 48: The graben has a markedly asymmetri
Page 53 and 54: are a valuable addition to the rout
Page 55 and 56: to 400 m) the calculated values for
Page 57 and 58: RISK ANALYSIS The created hazard ma
Page 59 and 60: 290 m water depth the basin accumul
Page 61: CONCLUSIONS From the palaeostress a
Page 71 and 72: however, the massive 1995 earthquak
Page 73 and 74: mapped on the slopes above Qiryat
Page 77 and 78: interpreted as either an expression
Page 79 and 80: The Shepran Cave is located on the
Page 87 and 88: properties. The mean value of speci
Page 91 and 92: excavated a deep trench, thus provi
Page 99 and 100: Fig. 8: Seismic ground shaking may
Page 101 and 102: elevant qualitative criteria are po
Page 103 and 104: CONCLUDING REMARKS The exposed exam
Page 105 and 106: produced by significantly different
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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The city collapsed and it was aband
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Fig. 4: Slipped lintel in a window
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to overcome shear resistance and in
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Newmark, N.M. (1965). Effects of ea
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associated with various tsunamis (<
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this method, the magnitude of the e
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etween pieces. Fragments have not f
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on the exact date of the earthquake
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THE ARCHAEOLOGICAL ZONE COLOGNE Aft
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affecting the Alcázar was about 50
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archaeoseismology could instead bec
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In the area later occupied by Vilni
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Fig. 2: Assemblage of landforms ass
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Fig. 8: Data and regression for mag
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Fig. 3: Relationships among magnitu
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CONCLUSIONS 1. Spatial distribution
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The stratigraphic sequence (Fig. 4)
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especially in the zones of hanging
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interpretations are based on relati
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Fig. 5: Gray‐scale value laser im
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(~40 cm), F‐ rotated building str
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Index 1 st INQUA‐IGCP‐567 Inter
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Archaeoseismology and Palaeoseismology in the Alpine ... - Tierra

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