1 Giornale di Geologia Applicata 1 (2005) , doi: /GGA The Rock of Orvieto (Umbria, Central Italy) Corrado Cencetti, Pietro Conversini & Paolo Tacconi Department of Civil and Environmental Engineering, University of Perugia Via G. Duranti, Perugia (Italy) ABSTRACT. Orvieto, about 100 km north of Rome, was built by the Etruscans on a massive rock of limited extension, a relict left by the erosion of the Alfina tuffaceous plateau. The latter was produced in the Pleistocene by the magmatic activity of the Vulsin Apparatus in northern Latium. The bedrock of the Rock of Orvieto is composed of Plio-Pleistocene marine clays which, owing to their high erodibility, represent a sinking substratum, causing falls and topples which have affected the edges of the cliff since historical times. Along with the installation of a complex monitoring system of piezometers, inclinometers and extensometers stationed along all the cliff edge, stabilization works were carried out, consisting of nails, anchors (passive in the upper portion and active in the basal portion of the Rock), drain pipes and waterproofing works for avoiding water infiltration into the rocky mass. Key terms: Geomorphology, Landslides, Orvieto, Umbria. Introduction The town of Orvieto is in the province of Terni (Central Italy), about 100 km north of Rome, standing on the northern edge of a broad volcanic plateau from the Quaternary period (Alfina plateau) that covers all of northern Latium, crossing over the border into Umbria (FIG. 3). Orvieto (from the Latin Urbs Vetus, or old town ) owes its particular character to the fact that it was built - by the Etruscans in the 9th-8th century BC - on a Rock of limited extension (approx. 1.3 km 2 ) which is one of the relicts left by the erosion of the Alfina tuffaceous plateau (FIG. 1). Because of the way it is built, this historic town is very vulnerable, made highly unstable due to natural causes, essentially the landslides which have occurred for centuries along the edges of the Rock, reducing its area over time and constituting a direct threat to the historic center and its splendid monuments (FIG. 2). Fig. 1 Panoramic view of the Orvieto s Cliff. Fig. 2 The front of the Orvieto s Cathedral, one of the most important monuments of the Gothic architecture in Italy.
2 Corrado Cencetti, Pietro Conversini. Paolo Tacconi / Giornale di Geologia Applicata 1 (2005) Fig. 3 Geological sketch of the Orvieto area, at the boundary between Latium and Umbria (central Italy). LEGENDA: 1) talus (Olocene); 2) recent and present alluvial sediments, also terraced (Olocene - Upper Pleistocene); 3) volcanic rocks of the Alfina Plateau (Middle Pleistocene); 4) gravels, sands and clays (marine clastic sediments, Lower Pleistocene Pliocene); 5) marls and sandstones (pre- Pliocenic bedrock); 6) River Paglia and its main tributaries. The Orvieto case differs only marginally from other towns of the same region (Bardano, Rocca Ripesena, Rocca Sberna, Civita di Bagnoregio) which developed in similar morphological conditions and, as a consequence, currently show similar instability phenomena (PANE & MARTINI, 1997). Orvieto was included in the list of towns to be consolidated entirely with State funds by Royal Decree no of 4 March Since that date and up to the present, a number of works have been carried out for the consolidation and stabilization of the Rock, which have made it possible to protect and preserve it. In particular, the worsening of the instability processes led to the passing of a national law (230/78 and subsequent amendments) for urgent consolidation works on the Rock to protect its historic-artistic heritage. The present study, which falls within the activities of the special Technical-Scientific Commission established by the Region of Umbria following the enactment of Law no. 545 of 1987 as the advisory board for consolidation works ( Permanent Observatory for the Monitoring and Maintenance of the Rock of Orvieto - Conversini et al., 1996), illustrates the geological, geomorphological, and hydrogeological characteristics that lie behind the instability of the Rock and the town of Orvieto, as well as the consolidation works which have been done and their current monitoring network. Its aim is to avoid the possibility of further landslide phenomena which might threaten one of the most important historic centers of ancient origin in Italy. Geological description of the Rock of Orvieto Geological-structural configuration The current geological configuration of the Orvieto area is the result of neotectonic and volcanic events taking place in the Quaternary period. The substratum of the volcanic plate of the Alfina plateau is composed of Pliocene marine clays; when the sea had definitively receded from the area, it
3 Corrado Cencetti, Pietro Conversini. Paolo Tacconi / Giornale di Geologia Applicata 1 (2005) underwent an extensional tectonic stage during the Lower Pleistocene (CATTUTO et al., 1994). This resulted in a normal fault (FIG. 4-a) striking approximately NW-SE, the raised block of which acted as a wall against which the volcanic magma flows and pyroclasts of the Apparato Vulsino accumulated. These are what form the Alfina plateau, dating from the Middle Pleistocene. The Paglia river, one of the most important tributaries of the Tiber River which currently flows at the foot of the tuffaceous Rock of Orvieto, cut its bed in a selective manner, along this line of tectonic displacement. The tuffaceous plate thus remained progressively raised in relation to the lowering of the Paglia valley and increasingly farther from the main course of the river (FIG. 4-b). At the same time that the Paglia river was cutting its valley, its tributaries on the right dismembered the large tuffaceous plate, often through regressive erosion phenomena (FIG. 4-c). This is still well preserved and cut off toward the SW, while toward the NE it is progressively reduced into mesas (such as Bardano and, of course, Orvieto), which may reach the dimensions of isolated pinnacles, or buttes (such as Rocca Ripesena or Rocca Sberna). Fig. 4 Schematic evolution of the Orvieto s area during Quaternary age. From CATTUTO et alii (1994), modified. Stratigraphic characteristics In detail (PIALLI et al., 1978; CONVERSINI et al., 1995), the stratigraphic sequence of the area is characterized, from the lower layers up (FIG. 5), by marine clays, followed by a sequence in fluvial-lacustrine facies of limited thickness ( Albornoz Series ) and finally by the tuffaceous plate which constitutes the Rock itself. The basal clays Clays constitute the base of the stratigraphic sequence in the entire Orvieto area. Attributed to the Middle Pliocene, due to their malacological and microfossil content they have a bluish color, tending toward gray and toward yellowish if altered. The CaCO 3 content is relatively high (marly clays), and in some areas is even greater than 40% (argillaceous marls). They also have a good percentage of micaceous silt, which gives them a characteristic luster. Their structure is in large, massive banks, in a sub-horizontal position. They are overconsolidated and thus frequent fissuring appears. The clays can be seen cropping out on the slopes of the Orvieto hill up to the base of the tuffaceous plate. The geometry of their roof, deduced from mechanical and geoelectrical drillings, shows a general inclination toward NNE, with a very gentle slope in the eastern part of the town, and a steeper slope in the western part. The Albornoz Series Following the clays in a slight angular unconformity is the Albornoz Series, which can be seen cropping out on both the WSW side of the Rock and also on the side facing ENE. This series, which is in a fluvial-lacustrine facies, dates to the Lower Pleistocene. It has a limited thickness (max. 15 meters) and is composed, from the bottom upwards, of: - a sandy-conglomerate layer, which contains blocks of basaltic lava and is formed mainly of arenaceous and calcarenitic pebbles in an imbricate structure (thus sedimented through the action of tractive currents); - a layer of nut-brown calcareous silts, containing altered pumice cinders and fresh water gastropods; - a layer of white limestone with diatoms and black pumicetype cinders. The presence of diatoms and fresh water fossils in this and the preceding layer unmistakably indicates a lacustrine environment; - a layer of pumiceous clasts, with a poor ash matrix, which marks the transition to the actual tuffaceous plate. There are very few outcrops of this series lying between the basal clays and the tuffaceous cliff (heads of the Civetta and Salto del Livio Gullies, Porta Maggiore, Porta Romana, St. Zero). Underground, however, all the drillings done through the tuffaceous plate have found the complete series.
4 Corrado Cencetti, Pietro Conversini. Paolo Tacconi / Giornale di Geologia Applicata 1 (2005) The Tuffaceous Plate As mentioned earlier, the tuffaceous plate is an erosion relict situated at the edge of the broad Alfina plateau produced by the volcanic activity of the Apparato Vulsino roughly 315,000 years ago. The Rock of Orvieto, made up of pyroclastites generally of a trachyte-phonolite composition, is the result of the cooling of a high temperature pyroclastic flow, partially hardened immediately after being deposited. Evidence of this is seen in the two distinct facies which characterize the Rock: the first has a more marked stony appearance (sillar facies), with sub-vertical fissures from cooling and a reddish-yellow color; the other ( pozzolana ) can be traced to a loose mass, blackish-grey in color and without evident fissuring. The two facies are distributed in an inhomogeneous manner along the perimeter of the Rock, varying from one zone to the next without spatial continuity (CONVERSINI et al., 1995). Fig. 5 - Geological schematic section of the Orvieto Cliff (from CONVERSINI et alii, 1995, modified). The lithoid facies is more easily identifiable, as it is generally characterized by more abundant fissuring and by prisms with typical columnar fracturing (of primary origin, due to contractions from cooling of the pyroclastic material, FIG. 6). The pozzolana facies, instead, had less fracturing and typical erosional forms ( tafonature alveolari, AMBROSINI & MARTINI, 1995). On the top of the Cliff, at the eastern edge, there is a limited outcrop of travertine, in lacustrine facies, very stratified, spongy, and containing numerous remains of plant origin. This modest outcrop is the remains of what was surely a much larger deposit, which extended toward the SSW. Fig. 6 The Rock of Orvieto before the stabilization works. You can note the columnar fracturing affecting the tuffaceous mass (photo by P. Marconi).
5 Corrado Cencetti, Pietro Conversini. Paolo Tacconi / Giornale di Geologia Applicata 1 (2005) Lastly, layers of detrital deposits produced by the mechanical weathering of the Rock surround its entire perimeter and are variously distributed on the slopes, whose substratum consists of the basal clays. The detritus is composed of tuffaceous elements highly variable in size, immersed in a pozzolana and ash matrix; the larger sized blocks are generally found along the northern slope of the Rock. Geomorphologic characteristics The tuffaceous cliff upon which Orvieto rises has a fairly elliptical shape, with the longer axis oriented in a ENE- WSW direction (FIG. 7). Its position is sub-horizontal, with vertical or sub-vertical walls, the highest along the southwestern side. It is 1500 meters long, about 700 meters at its widest point, and between 40 and 70 meters thick. The Rock lies on the summit of a hill which has gently inclined slopes (15-18 ) and is smoothly joined by a broad covering of detritus with the alluvial plain lying before it, formed by the Paglia river. Locally, there are deep gouges along the sides of the cliff, up to a maximum of meters deep, produced by gullies that flow across the clayey substratum, whose heads reach the upper edge of the Rock (Salto del Livio Gully, Civetta Gully, St. Zero Gully, St. Benedetto Gully and Cavaiene Gully). Fig. 7 Schematic geomorphological map of the Rock of Orvieto. From CONVERSINI et alii (1995), modified. Hydrogeological and hydrological characteristics Hydrogeological features The formations and the clastic deposits of the Rock of Orvieto (Albornoz Series, tuffaceous plate, travertines at the summit and tuff detritus) are permeable from porosity or from fracturing; the basal clays, on the other hand, have such low permeability that they can be considered to be practically impermeable. The different degrees of permeability affect the circulation of groundwater. The meteoric water passes through the upper rock, and is stopped when coming into contact with the basal clays. Thus a continuous water table is formed which feeds various springs, located here and there around the perimeter of the hill. In general two spring levels can be identified: one in contact with the Albornoz and the basal clays, and thus very near to the tuffaceous wall; the other scattered along the slopes of the hill, in the morphologically lowest areas or wherever the detritus-basal clay contact has been uncovered (CONVERSINI et al., 1995). In 1978, thirty-one springs were counted; their overall flow was calculated at approximately 8 l/s, for a total of 252 m 3 /year. Recent investigations have shown that this value is
6 Corrado Cencetti, Pietro Conversini. Paolo Tacconi / Giornale di Geologia Applicata 1 (2005) compatible with the amount of precipitation in the Orvieto area, confirming the validity of the proposed hydrogeological model. The chemical composition of the water allows them to be classified as bicarbonate-calcicalkaline, characterized by a high nitrate content (well above the levels of natural groundwater), which is undoubtedly due to man s millenary occupation of the Rock of Orvieto. Hydrological features The five major gullies that furrow the slopes of the Hill of Orvieto are fed by both meteoric water (coming from the top) and by the springs located at the foot of the tuffaceous cliff and along the slopes of the hill. As is to be expected, their catchment areas are quite small: the largest is that of the St. Benedetto Gully, which covers an area of about 1.5 km 2. Their discharges are quite variable and depend essentially on the amount of precipitation, which averages 870 mm/year (this result was obtained from the data in the hydrological annals for the period). The uncontrolled flows of meteoric water have increased the erosion processes over time, and have brought about the receding of the river heads and the undermining of the foot of the tuffaceous cliff, thus triggering landslides. In the plains areas, instead, there are frequent episodes of inundations and flooding, especially in connection with severe storms (a 1965 storm had the heaviest rainfall ever recorded, which reached a peak of 105 mm/hour). The streams flooding most often were the St. Benedetto Gully and the Cavaiene Gully, along their final stretch just before they empty into the Paglia river (CONVERSINI et al., 1995). Landslide phenomena Landslide types The general picture of the instability of the Hill and Rock of Orvieto is closely connected with the lithological characteristics of the two morphological entities. Along the slopes of the hill, which are made up of basal clays covered by an extensive layers of detritus, landslide movements result from rotational and translational slides, which can involve the two rock types separately or together. A typical example of this type is the Porta Cassia landslide, which was first reported in 1904 and covers an area of about 2.5 hectares, with a sliding surface depth varying from 3-4 meters up to meters. The main cause of these landslides is to be found in the saturation processes of the detritus layers or of the most superficial parts of the basal clays. This saturation is connected with the presence of the water table described earlier. Along the perimeter of the tuffaceous plate, however, the rock failure mechanisms are many and can be traced to: the lowering of blocks along the upper edge, falls or toppling of blocks in the middle-upper part, and the basal fracturing of prisms of various sizes (FIG. 8). The rock failure mechanisms of the Rock are closely connected with the fracturing of the tuffaceous mass, very evident along all of its perimeter, which is the result of the cooling stages of the high- temperature pyroclastic flow. The instability processes are due to the different deformability of the plate compared to the underlying clays, to the high state of stress at the foot of the tuffaceous wall, and to the alteration of the mechanical characteristics of the rock types due mostly to atmospheric agents. Added to these causes are anthropic activities, linked to the millenary presence of man, who exploited the tuff of the Rock for use as a building material. Also significant are the concessions issued by the local authorities for the extracting of pozzolana from inside the Rock, resulting in the excavating of the caves which characterize subterranean Orvieto today. Fig. 8 Main mechanisms of instability of the Rock of Orvieto: A) rotational slides at the toe; B) lowering of marginal slices; C) toppling and rolling; D) fall and basal rupture (after Regione Umbria, 1990). Historic landslides The instability of the Rock of Orvieto and of the underlying hill has been known for centuries (MARTINI & MARGOTTINI, 2000). There are fragmentary accounts up to the 13th century: in 1150, following heavy rains, landslides were reported along Ripa di Mezzogiorno, above Corno di Surripa, near the Porta Pertusa (today Porta Romana). Later, Ser Tommaso di Silvestro, in his Diario (R.I.S., 1990), describes a landslide which took place near the convent of St. Ludovico. Up until the 17th century another 22 landslides are reported to have occurred on both the Rock and the slopes.
7 Corrado Cencetti, Pietro Conversini. Paolo Tacconi / Giornale di Geologia Applicata 1 (2005) Between 1795 and 1796, following a worsening of the instability, the Castellan of Orvieto ordered that a survey be made to verify the overall stability of the Rock. Documents from the 19th century (REGION OF UMBRIA, 1979) give reports of landslides taking place along the perimeter of the tuffaceous plate, particularly in the area between Porta Rocca and the Fontana del Leone. The largest landslide occurred at the end of the century, near the Convent of St. Chiara. It was described by VINASSA DE REGNY (1904), who attributed the causes of the landslide to the presence of altered tuffs and pozzolana in that area. In early 1900s, the Porta Cassia landslide, the largest in historical times, took place after a brief period of heavy rainfalls. This was also described by VINASSA DE REGNY (1904, 1905). From the start of the 20th century until the present, falls in the tuffaceous plate and landslides of other types along the slopes have followed each other continuously. The latter have almost always been located at the heads of certain gullies, in particular the Civetta Gully, the Salto del Livio Gully, and the Cavaiene Gully, where the main cause can be attributed to the strong erosion of the basal clays by streams. Stabilization Works Starting in the late 1970s, following the laws enacted in 1978, 1984 and 1987, a series of works have been planned for the definitive consolidation of the Rock and the stabilization of landslides. Main works The main works, which by now are nearing completion, can be summarized as follows (CONVERSINI et al., 1995): - the water network, including the conduction network and the reservoir, were completely rebuilt. Added to this was the replacement, or at least the renewing, of the entire drainage system, with the building of the relative junction wells and connections to the purifier; - the gullies originating at the Rock were entirely diked, reshaped, and partially covered, in order to reduce or eliminate the erosion processes taking place, such as the deepening of the bed and the collecting of unstable material at the sides of the valleys; - the slopes of the hill were reforested, improvements were made to control the flow of water, and all springs were tapped; - the edge of the Rock was also reshaped, with the building of walls, impermeabilization works, and the planting of greenery; - works were also carried out to stabilize the landslides along the slopes of the hill, including the building of support structures, trenches, drainage wells and the morphological rearrangement of the slopes; Fig. 9 Scheme of the strenghtening works along the edge of the Rock (after CONVERSINI et al., 1995). - the tuffaceous wall was consolidated following a plan adaptable to local needs, taking into due consideration the geometry of the front, its degree of fracturing and the degree of degradation of the wall itself, as well as the environmental value of the site. The plan (FIG. 9) also called for active anchorages at the foot of the Rock (so as to obtain a partial recompression of the tuff) and passive anchorages located on the upper part of the wall, in order to prevent the outermost stone blocks from toppling over. Ample suspension work was also done on the front, bolting down the rock in order to prevent the system of fissures from propagating. At the same time, the cementing of the bolts had as a beneficial side effect also the widespread cementing of the existing fractures; - the existent city walls standing on the Rock and built in various historical periods were consolidated and restored for preservation (FIGS 10-11), which involved removing plant growth, cementing and cramping loose stones, replacing deteriorated stones, raising the walls, and building underpinnings and buttresses; - the numerous artificial caves in the tuffaceous Rock were also consolidated, to prevent the roofs from collapsing and the surface from caving in; depending on the historicalarcheological importance of the cave, the choice was made whether to simply fill them with mortars of lightened pozzolana mixtures, or to consolidate them with support works, the reinforcing of the walls and cementing, cramping and bracing. Some of these caves are now open to the public and are one of the most interesting tourist attractions.
8 Corrado Cencetti, Pietro Conversini. Paolo Tacconi / Giornale di Geologia Applicata 1 (2005) Figs The stabilization works on the Rock (photo by P. Marconi). The monitoring of the works carried out Subsequently, thanks again to the intervention of the Region of Umbria, monitoring and surveillance systems were set up for the analysis and monitoring of the stabilization and preservative restoration works carried out. Thus 89 long-base, single and triple extensometers were set up along the perimeter of the Rock to monitor the movements of the tuffaceous plate. The monitoring network consists of 142 sensors set up at 17 measuring stations. Temperature sensors were also connected to the extensometers and placed at various depths in the tuffaceous plate, so as to monitor changes in temperature. The piezometric levels of the water table were also subject to monitoring, in particular to correlate variations in the piezometric surface level with any landslides occurring. The network consists of 90 Casagrande-type piezometers located both at the top of the cliff and along the slopes of the hill. About two-thirds of the piezometers are equipped with electric sensors, so as to create a manual/automatic and centralized measurement system. The piezometers were linked to a meteorological data station. Eighty inclinometric tubes were also installed, and 16 of these, placed at the most significant locations, were equipped with centralized automatic reading devices. The entire system was completed with a series of points for the topographic (planimetric-altimetric) monitoring of the Rock and the slopes, set up both in the intervention areas and in those which have remained stable. The system uses both traditional and GPS measurement techniques. References A.G.I. - ASSOCIAZIONE GEOTECNICA ITALIANA (1991) The contribution of geotechnical engineering to the preservation of italian historical sites Introductory volume. Proc. of X E.C.S.M.F.E., Florence. ALVAREZ W. (1972) - The Treia Valley North of Rome: volcanic stratigraphy, topographic evolution and geological influences on human settlement. Geologica Romana, 11, , Roma. ALVAREZ W. (1975) - The Pleistocene volcanoes North of Rome. In: Geology of Italy, Earth Sci. Soc., Arab Republic, Tripoli, ALVAREZ W., GORDON A. & RASHAK E.P. (1975) Eruptive source of the Tufo rosso a scorie nere, a Pleistocene ignimbrite, North of Rome. Geologica Romana, 14, , Roma. AMBROSINI S. & MARTINI E. (1995) Abitato di Orvieto. In Studio dei Centri Abitati Instabili in Umbria. Atlante Regionale (Felicioni G., Martini E. & Ribaldi C. Eds.). CNR-GNDCI, Publ. No. 979, BALDI P., DECANDIA F.A., LAZZARETTO A. & CALAMAI A. (1974) Studio geologico del substrato della copertura vulcanica laziale nella zona dei laghi di Bolsena, Vico e Bracciano. Memorie della Società Geologica Italiana, 13, BASILICI G., BROZZETTI F., CENCETTI C., CONVERSINI P., STOPPA F. & TACCONI P. (2000) Geological, Geomorphological and Hydrogeological Maps of the Todi Hill and the Orvieto Cliff (Umbria, Central Italy). 31st International Geological Congress (Rio de Janeiro, Brazil, August 6-17, 2000). BECCALUVA L., BROTZU P., MACCIOTTA G., MORBIDELLI L., SERRI G. & TRAVERSA G. (1987) Caenozoic tectono-magmatic evolution and inferred mantle source in the Sardo- Tyrrhenian area. In: BORIANI A., BONAFEDE
9 Corrado Cencetti, Pietro Conversini. Paolo Tacconi / Giornale di Geologia Applicata 1 (2005) M., PICCARDO G.B. & VAI G.B. (Eds) The lithosphere in Italy Advances in Earth Science Research, Mid-term. Conference of the Italian National Comittee for the International Lithosphere Programm, Rome, May, 1987, preprint volume, CATTUTO C., CENCETTI C. & GREGORI L. (1994) - Gli itinerari. Itinerario n. 7 (da Orvieto a Spoleto). Prima parte: da Orvieto a Todi (Sosta 7.1 Panorama sulla Rupe di Orvieto). In: Guide Geologiche Regionali (a cura della Società Geologica Italiana) - Appennino umbromarchigiano, 7, CATTUTO C., CENCETTI C. & GREGORI L. (1994) - Gli itinerari. Itinerario n. 7 (da Orvieto a Spoleto). Prima parte: da Orvieto a Todi (Sosta 7.2 Il piastrone tufaceo di Orvieto e i suoi dissesti). In: Guide Geologiche Regionali (a cura della Società Geologica Italiana) - Appennino umbro-marchigiano, 7, CATTUTO C., CENCETTI C. & GREGORI L. (1994) - Gli itinerari. Itinerario n. 7 (da Orvieto a Spoleto). Prima parte: da Orvieto a Todi (Sosta 7.3 Panorama sulla valle del F. Paglia). In: Guide Geologiche Regionali (a cura della Società Geologica Italiana) - Appennino umbro-marchigiano, 7, CAVALLO B. (1995) Orvieto ipogea ovvero della proprietà del sottosuolo. Regione dell Umbria, Assessorato dell Area Ambiente e Infrastrutture. CESTELLI GUIDI C., CROCI G. & VENTURA P. (1983) The stability of the Orvieto Rock. Proc. of V Congress Int. Soc. of Rock Mechanics, C31-C38, Melbourne. CIVETTA L., FRANCALANCI L., MANETTI P. & PECCERILLO A. (1987) Petrological and geochemical variations across the Roman Comagmatic Province: Inference on magma genesis and crust-mantle evolution. In: BORIANI A., BONAFEDE M., PICCARDO G.B. & VAI G.B. (Eds) The lithosphere in Italy Advances in Earth Science Research, Mid-term. Conference of the Italian National Comittee for the International Lithosphere Programm, Rome, May, 1987, pre-print volume, CLERICI E. (1895) Sopra un nuovo giacimento diatomitico presso Orvieto e sui blocchi di argilla contenuti nei materiali vulcanici sostenenti questa città. Bollettino della Società Geologica Italiana, 14, , Roma. CONVERSINI P., LUPI S., MARTINI E., PIALLI G. & SABATINI P. (1978) Rupe di Orvieto. Indagini geologico-tecniche. Quaderni Studi della Regione dell Umbria, 82 pp., Perugia. CONVERSINI P., MARTINI E., PANE V., PIALLI G., TACCONI P., TORTOIOLI L. & UBERTINI L. (1995) La Rupe di Orvieto e il Colle di Todi: due casi di città fragili. Proc. of 1 Convegno del Gruppo Nazionale di Geologia Applicata (Giardini Naxos, Messina, June 11-15, 1995). Geologia Applicata e Idrogeologia, 30 (1), CONVERSINI P., PANE V., PIALLI G. & FABRIZI O. (1996) The preservation of historical towns of Umbria: the Orvieto case and its Observatory. Proc. Int. Symp. on Preservation of monuments and historic sites (Napoli, October 1996). CURLI G. & MARTINI E. (1986) Rupe di Orvieto Controllo della stabilità dei pendii. Proc. of 16 Convegno Nazionale di Geotecnica (May 14-16, 1986, Bologna). DIAMANTI L. & SOCCODATO C. (1981) Consolidation of the Historical Cities of Santeo and Orvieto. Proc. of X Int. Conf. on Soil Mechanics and Foundation Engineering, Vol. 3 (Stoccolma, 1981). FARAONE D. & STOPPA F. (1988) Il tufo di Orvieto nel quadro dell evoluzione vulcanotettonica della caldera di Bolsena, Monti Vulsini. Bollettino della Società Geologica Italiana, 107, , Roma. HOLM P.M. (1982) Mineral chemistry of perpotassic lavas of the Vulsinian district, the Roman Province, Italy. Miner. Magaz., 46, HOLM P.M., LOU S. & NIELSEN A. (1982) The Geochemistry and Petrogenesis of the lavas of the Vulsinian District, Roman Province, Central Italy. Contrib. Mineral. Petrol., 80, Lavecchia G. (1988) THE TYRRHENIAN- APENNINES SYSTEM: STRUCTURAL SETTING AND SEISMOTECTOGENESIS. TECTONOPHYSICS, 147, LEMBO FAZIO A., MANFREDINI G., RIBACCHI R. & SCIOTTI M. (1984) Slope failure and cliff instability in the Orvieto Hill. Proc. of IV Int. Symp. on Landslides (Toronto, September, 1984). LEMBO FAZIO A., RIBACCHI R., SCIOTTI M. & TOMMASI P. (1986) Meccanismi di dissesto della Rupe di Orvieto. Proc. of European Meeting on Idrogeologia, protezione e conservazione del patrimonio storico-culturale (Orvieto, May 22-23, 1986), 17 pp. LOCARDI E., FUNICIELLO R., LOMBARDI G. & PAROTTO M. (1977) The main volcanic groups of Latium: relations between structural evolution and petrogenesis. Geologica Romana, 15, LOTTI B. (1908) Sulla frana di Porta Cassia presso Orvieto. Bollettino Regio Comitato Geologico d Italia, 39, 1, 36-41, Roma. LOTTI B. (1926) Descrizione geologica dell Umbria. Memorie Descrittive della Carta Geologica d Italia, 21, 320 pp. LUNARDI P. & FORNARO M. (1980) Criteri di scelta per interventi di consolidamento della Rupe di Orvieto e proposte operative. Proc. of A.G.I. XIV Convegno Nazionale di Geotecnica (Firenze, October 28-31, 1980). MANETTI P. & PECCERILLO A. (1986) Caratteri petrologici delle vulcaniti potassiche italiane: considerazioni genetiche e geodinamiche. Pre-print Proc. 73 Congresso della Società Geologica Italiana, Roma, MANFREDINI G., MARTINETTI S., RIBACCHI R. & SCIOTTI M. (1980) Problemi di stabilità della Rupe di Orvieto. Proc. of A.G.I. - XIV Convegno Nazionale di Geotecnica (Firenze, October 28-31, 1980), 1, MARTINI E. & MARGOTTINI C. (2000) Le frane storiche di Todi e Orvieto. Pubblicazione a cura dell Osservatorio della Rupe di Orvieto e del Colle di Todi, Regione dell Umbria, Perugia. MARTINI E., PIALLI G. & SABATINI P. (1980) Bacterial contamination beneath Orvieto, Italy. Acquifer contamination and Protection - UNESCO Studies and Reports in Hydrology, 30, , Paris. NAPPI G., CHIODI M., ROSSI S. & VOLPONI E. (1982) L ignimbrite di Orvieto nel quadro della evoluzione vulcanotettonica dei Vulsini orientali. Caratteristiche geologiche e tecniche. Bollettino della Società Geologica Italiana, 101, PANE V. & MARTINI E. (1997) The preservation of historical towns of Umbria: the Orvieto case and its observatory. Proc. of Geotechnical Engineering for the Preservation of Monuments and Historic Sites (Viggiani Ed.). Balkema, Rotterdam, PIALLI G., MARTINI E. & SABATINI P. (1978) Contributo alla conoscenza della Geologia del Colle di Orvieto. Bollettino della Società Geologica Italiana, 97, , Roma. REGIONE DELL UMBRIA (1979) Progetto generale esecutivo e Progetti stralcio per il consolidamento della Rupe di Orvieto ai sensi della L. 230/78, Perugia. REGIONE DELL UMBRIA (1985) Progetti di massima e programma per il completamento del consolidamento della Rupe di Orvieto ai sensi della L. 227/84, Perugia. REGIONE DELL UMBRIA (1988) Progetto generale di massima per il definitivo consolidamento della Rupe di Orvieto ai sensi della L. 545/87, Perugia. REGIONE DELL UMBRIA ( ) Progetti esecutivi per il definitivo consolidamento della Rupe di Orvieto ai sensi della L. 545/87, Perugia. R.I.S. RERUM ITALICORUM SCRIPTORES (1900) Raccolta degli storici italiani dal cinquecento al millecinquecento, ordinata da Ludovico Antonio Muratori. Vol. 15/5, App. Vol. 1. SPARKS R.S.J. (1975) Stratigraphy and Geology of the Ignimbrite of Vulsini Volcano, Central Italy. Geol. Rundschau, 64, TOMMASI P., RIBACCHI R. & SCIOTTI M. (1986) Analisi storica dei dissesti e degli interventi sulla Rupe di Orvieto: un ausilio allo studio dell evoluzione della stabilità del centro abitato. Geologia Applicata e Idrogeologia, 21, TORO B. (1978) Anomalie residue di gravità e strutture profonde nelle aree vulcaniche del Lazio settentrionale. Geologica Romana, 17, VAREKAMP J.C. (1980) The geology of the Vulsinian Area, Lazio, Italy. Bull. Volc., 43, VERRI A. (1905) Sulle frane di Orvieto. Bollettino della Società Geologica d Italia, 24, 31-32, Roma.
10 Corrado Cencetti, Pietro Conversini. Paolo Tacconi / Giornale di Geologia Applicata 1 (2005) VINASSA DE REGNY (1904) Le frane di Orvieto. Giornale di Geologia pratica, , Bologna. VINASSA DE REGNY (1905) A proposito delle frane di Orvieto. Bollettino della Società Geologica Italiana, 24, , Roma.
NAME DATE WEATHERING, EROSION, AND DEPOSITION PRACTICE TEST 1. The diagram below shows a meandering stream. Measurements of stream velocity were taken along straight line AB. Which graph best shows the
1. Hydrogelogical mapping Jiri Sima Aim of HG map Groundwater and rocks qualitative permeability and quantitative potential of rock units aquifers / aquitards / aquiclides Water points (spatial distribution
WILLOCHRA BASIN GROUNDWATER STATUS REPORT 2009-10 SUMMARY 2009-10 The Willochra Basin is situated in the southern Flinders Ranges in the Mid-North of South Australia, approximately 50 km east of Port Augusta
TEKS investigate rapid changes in Earth s surface such as volcanic eruptions, earthquakes, and landslides Rapid Changes in Earth s Surface Constant Changes Earth s surface is constantly changing. Wind,
GEOLOGY 306 Laboratory Instructor: TERRY J. BOROUGHS NAME: Examining the Terrestrial Planets (Chapter 20) For this assignment you will require: a calculator, colored pencils, a metric ruler, and your geology
Chapter 11 Slope Stabiliza bilization and Stability of Cuts and Fills THE OBJECTIVES OF ROUTINE ROAD CUTS AND FILLS are 1) to create space for the road template and driving surface; 2) to balance material
298 10.14 INVESTIGATION How Did These Ocean Features and Continental Margins Form? The terrain below contains various features on the seafloor, as well as parts of three continents. Some general observations
Earth Science - SOL 5.7 Science Study Guide Rocks are classified based on how they were formed. The three types of rocks are sedimentary, igneous, and metamorphic. Igneous rock forms when magma (liquid
1 2 A very short description of the functional center network: regarding the Hydraulic and Hydrogeological risk, the national alert system is ensured by the National Civil Protection Department (DPCN),
1. The climate that existed in an area during the early Paleozoic Era can best be determined by studying (1) the present climate of the area (2) recorded climate data of the area since 1700 (3) present
THE ADECO-RS APPROACH IN THE DESIGN AND CONSTRUCTION OF THE UNDERGROUND WORKS OF ROME TO NAPLES HIGH SPEED RAILWAY LINE: A COMPARISON BETWEEN FINAL DESIGN SPECIFICATIONS, CONSTRUCTION DESIGN AND AS BUILT
Illinois State Museum Geology Online http://geologyonline.museum.state.il.us Ride the Rock Cycle Grade Level: 5 6 Purpose: To teach students that the rock cycle, like the water cycle, has various stages
PRESENT ISSUES FOR CENTRE DE LA MANCHE DISPOSAL FACILITY M. DUTZER, J.P. VERVIALLE, P. CHARTON Andra - Agence Nationale pour la Gestion des Déchets Radioactifs 1-7 rue Jean Monnet, 92298 Châtenay-Malabry
Chapter Overview CHAPTER 3 Marine Provinces The study of bathymetry charts ocean depths and ocean floor topography. Echo sounding and satellites are efficient bathymetric tools. Most ocean floor features
Chapter 2 Flash Flood Science A flash flood is generally defined as a rapid onset flood of short duration with a relatively high peak discharge (World Meteorological Organization). The American Meteorological
National Rural Employment Guarantee Act Watershed Works Manual DRAINAGE LINE TREATMENT: GABION STRUCTURE Baba Amte Centre for People s Empowerment Samaj Pragati Sahayog September 2006 Drainage Line Treatment:
3.9 GEOLOGY, SOILS, AND SEISMICITY The Hawaiian Islands formed as the Pacific Plate moved over a relatively permanent hot spot in the mantle beneath the plate. The long chain of islands that stretch for
Mammal fauna remains in the Middle Pleistocene volcanic deposits from Northeastern Sabatini Volcanic District area (Latium, Italy) G. Sottili, P. Celletti Dipartimento di Scienze della Terra, Università
Minerals and Rocks Name 1. Base your answer to the following question on the map and cross section below. The shaded areas on the map represent regions of the United States that have evaporite rock layers
Siting and settlement: The most important way to protect shelter from floods is to build in a place that is unlikely to be flooded. Key Messages Shelters and settlements should be sited above the highest
Jackson Gulch Outlet Canal Rehabilitation Project Preliminary Budgetary Estimate for Rehabilitation February 2004 Prepared for the Mancos Water Conservancy District Jackson Gulch Reservoir 42888 County
1. Michigan Geological History Presentation (Michigan Natural Resources) The Michigan Geological History Presentation provides an overview of the approximately 3 billion years of Earth Processes that the
overflow can lead into a permeable conveyance system to increase further the benefit and reduce the need for pipe systems. Pollutant removal rates have been shown to be high, with some pollutants being
Chiara Berichillo THE SMALL CENTRE OF PIEGARO AND ITS ANCIENT LINKS WITH GLASS PRODUCTION The small village of Piegaro, of medieval origins, rises among the green hills of Umbria in the western part of
The Oceans Major Ocean Basins: Pacific Ocean largest and deepest Atlantic Ocean Indian Ocean S. Hemisphere Arctic smallest and most shallow Ocean Floor Geologic Provinces Continental Margin Continental
FROM SEDIMENT INTO SEDIMENTARY ROCK Objectives Identify three types of sediments. Explain where and how chemical and biogenic sediments form. Explain three processes that lead to the lithification of sediments.
An Interdisciplinary Response to Mine Water Challenges - Sui, Sun & Wang (eds) 2014 China University of Mining and Technology Press, Xuzhou, ISBN 978-7-5646-2437-8 Treatment Practice for Controlling Water
Objectives You will learn about how the land of North Dakota was formed. Introduction North Dakota is a wonderful place to live. Have you ever though about how it was formed? To answer that question, you
Geological Visualization Tools and Structural Geology Geologists use several visualization tools to understand rock outcrop relationships, regional patterns and subsurface geology in 3D and 4D. Geological
CIVL451 Soil Exploration and Characterization 1 Definition The process of determining the layers of natural soil deposits that will underlie a proposed structure and their physical properties is generally
Name: Class: _ Date: _ Rocks and Plate Tectonics Multiple Choice Identify the choice that best completes the statement or answers the question. 1. What is a naturally occurring, solid mass of mineral or
Reading Comprehension Name 1 How many people have been to the Rocky Mountains or the Grand Canyon? When people go to visit these natural wonders, they may not realize that it took millions of years for
Possible Submission about Water and Flooding (See maps 3a and 3b) From Mole Valley Local Development Framework: Strategic Flood Risk Assessment Update 2012 (http://www.molevalley.gov.uk/media/pdf/c/r/srfa_-_updated_jnauary_2012.pdf
Emergency Safeguarding of the World Heritage Site of Byblos Emergency Safeguarding of the World Heritage Site of Byblos Introduction Located on the Eastern Mediterranean, 40 km north of Beirut (Lebanon),
The Hydrologic Cycle Page 1 of 1 Name Directions: The hydrologic cycle consists of the processes that change and move water through the earth s system. Use the terms below to label the hydrologic cycle.
RIPRAP From Massachusetts Erosion and Sediment Control Guidelines for Urban and Suburban Areas http://www.mass.gov/dep/water/laws/policies.htm#storm Definition: A permanent, erosion-resistant ground cover
CHAPTER 4 1 The Rock Cycle SECTION Rocks: Mineral Mixtures BEFORE YOU READ After you read this section, you should be able to answer these questions: What is a rock? How are rocks classified? What does
Tectonics Assessment / 1 TECTONICS ASSESSMENT 1. Movement along plate boundaries produces A. tides. B. fronts. C. hurricanes. D. earthquakes. 2. Which of the following is TRUE about the movement of continents?
Create Your Own Soil Profile Ac5vity Middle School: 5-8 Task Overview: Soil profile refers to layers of soil. A typical soil profile takes nearly 1,000 to 100,000 years to form. The formation of the soil
Warsaw-natural environment How did the natural environment determine the development of the city? Agnieszka Chrząstowska-Wachtel http://www.varsovia.pl/varsovia/ What do we already know? Gdzie leży Warszawa?
NUMERICAL ANALYSIS OF SEEPAGE THROUGH EMBANKMENT DAMS (CASE STUDY: KOCHARY DAM, GOLPAYEGAN) *Reza Naghmehkhan Dahande 1 and Ahmad Taheri 2 1 Department of Civil Engineering-Water Management, Islamic Azad
Rocks and Minerals What is right under your feet? Name: 1 Before you start What do you already know? What is the difference between a rock and a mineral? What are the three categories of rocks? 1. 2. 3.
Lecture 7 Plates and Mantle Plumes Transform Boundaries Transform boundaries occur where one segment of rigid lithosphere slides horizontally past another in response to stresses in the lithosphere. The
PhD Course: Models and Methods for Materials and Environmental Sciences PhD student: Manuela Deiana Tutors: Dr Francesco Ronchetti, Prof. Alessandro Corsini Title: Stable and ustable isotopes applied to
THE TRANSITION FROM OPEN PIT TO UNDERGROUND MINING: AN UNUSUAL SLOPE FAILURE MECHANISM AT PALABORA Richard K. Brummer*, Hao Li* & Allan Moss *Itasca Consulting Canada Inc., Rio Tinto Limited ABSTRACT At
Characteristics of Sedimentary Rocks Deposited at the earth s surface by wind, water, glacier ice, or biochemical processes Typically deposited in strata (layers) under cool surface conditions. This is
Middle Pleistocene geology of the Bassa Campagna Romana D. De Rita 1, F. Zarlenga 2 1 Dipartimento di Scienze Geologiche, Università degli Studi di Roma Tre, Roma, Italia - email@example.com 2 Divisione
REPUBLIC OF SIERRA LEONE MINISTRY OF ENERGY AND WATER RESOURCES FEASIBILITY STUDY FOR MANUAL DRILLING MAPPING OF FAVOURABLE ZONES Page 2 of 22 TABLE OF CONTENTS Introduction 4 General context 5 Geography
Riprap-lined Swale (RS) Practice Description A riprap-lined swale is a natural or constructed channel with an erosion-resistant rock lining designed to carry concentrated runoff to a stable outlet. This
SPECIAL PROJECT PP5 HAMMER RelationsHips between meteo-climatic parameters and ground surface deformation time series in mountain environments F. Ardizzone, P. Allasia, M. Cignetti, D. Giordan, A. Manconi,
Sedimentary Rocks Practice Questions and Answers Revised September 2007 1. Clastic sedimentary rocks are composed of and derived from pre-existing material. 2. What is physical weathering? 3. What is chemical
Soil Gas Radon Concentration and Permeability at Valle della Caffarella Test Site (Roma, Italy). Evaluation of Gas Sampling Techniques and Radon Measurements Using Different Approaches Italian team Mauro
Please read chapters 10 and 5 CHAPTER 5 Sedimentary Rocks 1) Sedimentary rocks A) form by compaction and cementation of loose sediment. B) are widespread on the continents and ocean floor. C) are common
Catchment Scale Processes and River Restoration Dr Jenny Mant Jenny@therrc.co.uk The River Restoration Centre therrc.co.uk 3 Main Catchment Elements Hydrology Energy associated with the flow of water affects
SESSION 5: RIVER SYSTEMS KEY CONCEPTS: In this session we will focus on the following aspects: - Where the water in rivers come from. - Factors influencing run-off, infiltration (and rate of erosion) -
SEDIMENTARY ROCKS Sedimentary rocks are formed near or at the surface of the earth. They are derived from preexisting source rocks. They are composed by sediments, this is material that has been weathered,
3D Model of Carbon Relief in the Czech Part of Upper Silesian Coal Basin Vladimír Mandrla Green Gas DPB, a.s. tř. Rudé armády 637 739 21, Paskov Vladimir.Mandrla@dpb.cz Abstract. Coal mining in the Czech
Land Disturbance, Erosion Control and Stormwater Management Checklist Walworth County Land Conservation Department The following checklist is designed to assist the applicant in complying with the Walworth
Sedimentary Rocks, Processes, and Environments Sediments are loose grains and chemical residues of earth materials, which include things such as rock fragments, mineral grains, part of plants or animals,
Lecture Outlines PowerPoint Chapter 9 Earth Science, 12e Tarbuck/Lutgens 2009 Pearson Prentice Hall This work is protected by United States copyright laws and is provided solely for the use of instructors
Unit 6 Earthquakes and Volcanoes Earthquakes and Volcanoes: Essential Questions What evidence can students observe that the Earth is changing? How do scientists know what s inside the Earth? What processes
Brussels, 18-20 February 2008 Dissemination of information workshop 1 Eurocode 7 - Geotechnical design - Part 2 Ground investigation and testing Dr.-Ing. Bernd Schuppener, Federal Waterways Engineering
Weathering, Erosion, and Soils 1 The Grand Canyon, a landscape shaped by weathering and erosion 2 Weathering vs. erosion Types of weathering Physical Chemical Rates of weathering and erosion Climate Rock
MCLAREN VALE PWA GROUNDWATER LEVEL AND SALINITY STATUS REPORT 2009 10 SUMMARY 2009 10 The McLaren Vale PWA is located approximately 35 km south of Adelaide. It is a regional-scale resource for which groundwater
Proceedings 2005 Rapid Excavation & Tunneling Conference, Seattle EPB-TBM Face Support Control in the Metro do Porto Project, Portugal S. Babendererde, Babendererde Engineers LLC, Kent, WA; E. Hoek, Vancouver,
Geological Maps 1: Horizontal and Inclined Strata A well-rounded geologist must be familiar with the processes that shape the Earth as well as the rocks and minerals that comprise it. These processes cover
A CASE-STUDY OF CUA_DAT CFRD IN VIETNAM Giang Pham Hong, Michel Hotakhanh, Nga Pham Hong, Hoai Nam Nguyen, Abstract:Dams have been taken an important role in time and surface redistribution of water for
NATURAL WONDERS As you travel around Kentucky taking pictures, you are excited by what you see. Kentucky offers diverse and amazing sights. The Six Regions In the West, you see the Mississippi River, the
Relative Age Dating Comparative Records of Time Nature of the rock record principles of stratigraphy: deposition, succession, continuity and correlation Stratigraphic tools biological succession of life:
18 Planning, Health and Environment Division A Planning Guide to Sustainable Drainage Systems Introduction Working in co-operation with the Environment Agency, Severn Trent Water Ltd., the Highway Authority
Test 3 Earth Formation, Structure, Plate Boundaries, Volcanism Multiple Choice Identify the choice that best completes the statement or answers the question. 1. The shape of Earth most closely resembles
GEOTECHNICAL ISSUES OF LANDSLIDES CHARACTERISTICS MECHANISMS PREPARDNESS: BEFORE, DURING AND AFTER A LANDSLIDE QUESTIONS FOR DISCUSSIONS Huge landslide Leyte, Phillipines, 1998 2000 casulties Small debris
DOÑA ANA COUNTY DESIGN STORM CRITERIA GUIDELINES FOR COMMERCIAL AND RESIDENTIAL SITES Run-off Analysis Methods This document sets forth the minimum design, technical criteria and specifications for the
Centre Européen sur les Risques Géomorphologiques Les mouvements de terrain Études de cas : Glissements du Pays d Auge Prof. Olivier MAQUAIRE Faculté de Géographie, Université de Caen Basse-Normandie Laboratoire
1. The Use of Infiltration The use of infiltration to dispose of stormwater runoff has a number of important benefits: It can reduce the volume of runoff and the peak rates of runoff discharged from the
What is Soil Survey? Soil Survey is a systematic examination, description, classification, and mapping of the soils in a given area. Brady and Weil. 1996 Who Produces Soil Survey Cooperative effort between
UNIT 3 EXAM ROCKS AND MINERALS NAME: BLOCK: DATE: 1. Base your answer to the following question on on the photographs and news article below. Old Man s Loss Felt in New Hampshire FRANCONIA, N.H. Crowds
SECTION 5200 - STORM SEWER PART 1 - GENERAL 1.01 SCOPE: This Section covers installation of storm sewer mains and culverts. Topics include permits and fees, trench widths, pipe laying, bedding, initial
Review of Groundwater Vulnerability Assessment Methods Unsaturated Zone Dept. of Earth Sciences University of the Western Cape Background Sililo et al. (2001) Groundwater contamination depends on: Intrinsic
SLOPE AND TOPOGRAPHY What are Slope and Topography? Slope and topography describe the shape and relief of the land. Topography is a measurement of elevation, and slope is the percent change in that elevation
Earth Science Regents Questions: Plate Tectonics Name: Date: Period: August 2013 Due Date: 17 Compared to the oceanic crust, the continental crust is (1) less dense and more basaltic (3) more dense and
Name: Date: 1. The road shown below was suddenly broken by a natural event. 3. The convergence of two continental plates would produce Which natural event most likely caused the crack in the road? island
2. What is a subsurface dam? 2-1 Concept and principle of a subsurface dam A subsurface dam is a system to store groundwater by a cut-off wall (dam body) set up across a groundwater channel. It is similar