Archaeoseismology and Palaeoseismology in the Alpine ... - Tierra

More documents

Recommendations

Info

Fig. 1: Isoseismal Map (MSK) of the 1504 AD Carmona Earthquake based on historical descriptions and coseismic secondary effects illustrating categories of the ESI‐2007 Scale (ground cracks, slope movements, liquefaction processes, anomalous waves and flooding in rivers and temporary turbidity changes in wells) and sites with archaeoseismic damage (IGCP567 Logo). Epicentral location parameters (red star) and error radius are from FAUST PROJECT: http://faustproject.com. Yellow stars indicate the macroseismic location of other historic moderate events (VI‐VII MSK) Colours of localities indicate the recorded MSK intensity. White dots indicate no data. The delineation of isoseismal lines SE of Carmona is tentative (no data available for this zone) The 1504 AD Carmona Event can be considered a seismic sequence which lasted almost one month and a half, when a main aftershock (V EMS) caused damage in the previously affected macroseismic area. Before, in 1466 AD a previous strong event (VIII EMS) caused significant damage around the same area of the Guadalquivir valley, but especially in the cities of Carmona and Sevilla (Galbis, 1932). The seismicity of the zone records about 30 seismic events for the period 900 – 1900 AD along the Guadalquivir Valley following the suspect Guadalquivir Fault. There are four recorded historical macroseismic areas in Sevilla (VIII EMS), Carmona (VIII‐IX EMS), Córdoba (V‐VI EMS) and Andújar (VIII‐IX EMS). EFFECTS ON NATURAL ENVIRONMENT Coseismic ground effects produced by the earthquake can be classified as secondary effects of the ESI‐2007 Scale (Michetti et al., 2007) including the categories of Slope Movements and large ground cracks (Los Alcores Scarp and Carmona City, about 3 to 10 km away). Liquefactions were widely reported within the Guadalquivir flood plain between Sevilla and Palma del Rio (45 km away). Anomalous waves in the Guadalquivir River, were only reported in Sevilla, 23 km away from the epicentre. Finally, within the category of Hydrological changes, temporal variation in the turbidity of wells were reported on two distant localities (Amadén de la Plata y Cazalla), located in the palaeozoic basement on the NW margin of 1 st INQUA‐IGCP‐567 International Workshop on Earthquake Archeology and Paleoseismology 140 the Guadalquivir Depression, about 60 to 70 km away of the epicentral area. The isoseismal map of figure 1 is not a conventional one due to the scarcity of the macroseismic data. It only illustrates theoretical MSK‐ESI2007 intensity zones at the macroseismic area in relation to the topography (scarps) and the geology of the area (Guadalquivir flood plain) where main ground coseismic effects were recorded. Slope Movements and Rockfalls. These ground failures are mainly related with Los Alcores Scarp where the Carmona City is founded. This scarpment is a NW‐SE trending active geomorphic feature within the southern margin of the Guadalquivir river valley, subject to relevant rockfalls, large landslides triggering differential settlement of buildings (Rodríguez Vidal and González Diez, 1987; Serrat and Ruíz; 1988; Baena, 1993). Free face of the scarp develops in a 30 to 70 m thick calcarenitic unit, resting upon a thicker marly messinian sequence and plastic olisthostromic sequences coming from the Betic Cordillera front located to the SE. The Palaeozoic substratum is about 1000 metres depth beneath the City of Carmona, whilst in the opposite margin of the Guadalquivir valley, about 30 km NW, the metamorphic Palaeozoic materials outcrop at the surface (Fig. 1). Fig. 2: Blocks of the Landslide triggered by the 1504 AD Carmona Earthquake affecting to the ancient Arab Castle (Original Photo Hernández‐Pacheco, 1956) Los Alcores Scarp is 140 m high in Carmona to about 40m high in Alcalá de Guadaira (25 km SE) where the scarp progressively dies‐out. The scarp is a lineal geomorphic feature stepped by orthogonal NW‐SE and NNE‐SSW faults affecting to the Late Neogene calcarenites (Baena, 1993; Serrat and Ruíz, 1988). Faulting give place to relevant altitudinal changes of about 10‐5 m on the scarp elevation. However, most of these intervening faults have been the preferential place for gully development from the Middle‐Late Pleistocene, so their trace can only be delineated by means of the geomorphic anomalies recorded at the top of the scarp. Large landslide events were recorded along this scarp. The main one affected to the Alcázar (Arab Castle) of Carmona as documented by Bonsor (1918). Maximum vertical displacement of the slide was of 1.8 m with associated left lateral displacements of a maximum of 1.4 m. The larger fracture
affecting the Alcázar was about 500 m long, 6,6 m wide, seated to a depth of 8 m, where it is about 3.5m wide. The main fracture had a E‐W orientation in the Castle walls, but a NE‐SW towards the city for at least 1 km (Fig. 3). The total mobilised material for this individual landslide exceed 800,000 m 3 , indicating an ESI‐2007 intensity ≥ VIII. Additionally, large calcarenite blocks between 10 and 500 m 3 rolled downslope for a maximum distance of about 1 km (Figs. 3 and 4). Similar fractures and scattered rockfalls where also documented along 25 km between the localities of Carmona and Alcalá de Guadaira (Bonsor, 1918). Some of the individual blocks exceed 300 m 3 , as is the case of the Tartessic “Peña de los Sacrificios” (Century 8‐6 th BC) located at the ancient necropolis of “El Acebuchal” 3 km SW of Carmona. In this case this corresponds to more ancient large rockfall events previous to the 1504 event studied here. Finally, 1,5 km SE of Carmona rockfalls affected the ancient Visigoth graves (Century 5 th – 7 th AD) carved of the calcarenites at the top of the cliff in the Cuesta del Chorrillo Site about 1 km SE of the damaged Castle. Large blocks with inset Visigoth graves were removed from the cliff and rolled downslope. In this case rockfall events are older than the 8 th Century AD (Muslim Conquest of Iberia) but may correspond to pre 1504 AD events. Fig. 3: Aerial plant‐view (Goggle Earth) displaying the E‐W fracture on the Castle walls mapped by Bonsor (1918) in the framework of mapped landslide area and individual blocks that rolled down during the 1504 AD Carmona Earthquake. The recent building constructed on the ancient damaged ruins of the Castle is the Parador de Turismo of Carmona Fractures and Ground cracks. Main fractures and cracks occurred in relation with the aforementioned landslide event affecting the Alcázar (Fig. 3). The main open crack ruptured the hard‐rock calcarenitic substratum it was more than 1 km long and had a variable width from 0.85 to 5 m. The maximum width (2‐5 m) was recorded within the city close to the ancient Convent of “Los Jerónimos”. Two more subparallel large cracks where documented by Bonsor (1918). All these fractures had a broad orientation of E‐W at the cliff to NE‐SW within the city. Large cracks where also documented at the ancient roman necropolis of Carmona (1 st Century BC – 2 nd Century AD) affecting the big cave‐graves carved on the calcarenites with broad SE‐ NW orientation about 2 km East of the Alcázar. Cracks had centimetric opening affecting both the floors and the 1 st INQUA‐IGCP‐567 International Workshop on Earthquake Archeology and Paleoseismology 141 roofs of the graves, in some of them causing partial collapses of the roofs (Bonsor, 1918). Similar fractures occurred from a distance of 3 km SW of Carmona at the ancient Necropolis of “El Acebuchal”. Bonsor (1918) documented an open fracture of at least 500 m length affecting both, a post‐neolithic settlement and ancient tartessic graves (Century 8‐6 th BC). At the tartessic graves zone the fracture had about 200 m length, an opening of 0.5‐1.5 m and a depth of 3‐4 m, with a broad NE‐SW orientation. Features and dimensions of the aforementioned open cracks point to maximum IX‐X ESI‐ 2007 intensities over Los Alcores Cliff. Fig. 4: Present view of the Los Alcores Scarp at the ancient Arab Castle affected by landsliding during the 1504 AD event. Big arrows (landslided blocks 300 m 3 ). Small arrows (blocks
Page 1:
Abstracts Volume Archaeoseismology
Page 4 and 5:
Edita e imprime: Sección de Public
Page 7 and 8:
1 st INQUA‐IGCP‐567 Internation
Page 9 and 10:
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:
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 37 and 38:
Page 39 and 40:
Page 41 and 42:
Page 43 and 44:
Table 1: Surface faulting extent re
Page 45 and 46:
Page 47 and 48:
The graben has a markedly asymmetri
Page 49 and 50:
Page 51 and 52:
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 and 62:
CONCLUSIONS From the palaeostress a
Page 63 and 64:
Fig. 2: Geological map of the study
Page 65 and 66:
Page 67 and 68:
Page 69 and 70:
Page 71 and 72:
however, the massive 1995 earthquak
Page 73 and 74:
mapped on the slopes above Qiryat
Page 75 and 76:
Page 77 and 78:
interpreted as either an expression
Page 79 and 80:
The Shepran Cave is located on the
Page 81 and 82:
Page 83 and 84:
Page 85 and 86:
Page 87 and 88:
properties. The mean value of speci
Page 89 and 90:
Page 91 and 92: excavated a deep trench, thus provi
Page 93 and 94: 1 st INQUA‐IGCP‐567 Internation
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
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 141: 1 st INQUA‐IGCP‐567 Internation
Page 147 and 148: archaeoseismology could instead bec
Page 149 and 150: In the area later occupied by Vilni
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
Page 181: 1 st INQUA‐IGCP‐567 Internation
show all

Archaeoseismology and Palaeoseismology in the Alpine ... - Tierra

Create successful ePaper yourself

Delete template?

Save as template?