P13 Copertina R OK C August 20-28,2004 Florence -Italy
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Volume n° 3 - from D01 to P13 32nd INTERNATIONAL GEOLOGICAL CONGRESS LANDSLIDES OF THE EMILIA APENNINES Leader: G. Bertolini Associate Leaders: M.T. De Nardo, G. Larini, M. Pizziolo Field Trip Guide Book - P13 Field Trip Florence - Italy August 20-28, 2004 Post-Congress P13 P13_copertina_R_OK C 14-06-2004, 14:29:46 The scientific content of this guide is under the total responsibility of the Authors Published by: APAT – Italian Agency for the Environmental Protection and Technical Services - Via Vitaliano Brancati, 48 - 00144 Roma - Italy Series Editors: Luca Guerrieri, Irene Rischia and Leonello Serva (APAT, Roma) English Desk-copy Editors: Paul Mazza (Università di Firenze), Jessica Ann Thonn (Università di Firenze), Nathalie Marléne Adams (Università di Firenze), Miriam Friedman (Università di Firenze), Kate Eadie (Freelance indipendent professional) Field Trip Committee: Leonello Serva (APAT, Roma), Alessandro Michetti (Università dell’Insubria, Como), Giulio Pavia (Università di Torino), Raffaele Pignone (Servizio Geologico Regione Emilia-Romagna, Bologna) and Riccardo Polino (CNR, Torino) Acknowledgments: The 32nd IGC Organizing Committee is grateful to Roberto Pompili and Elisa Brustia (APAT, Roma) for their collaboration in editing. Graphic project: Full snc - Firenze Layout and press: Lito Terrazzi srl - Firenze P13_copertina_R_OK D 25-05-2004, 13:13:08 Volume n° 3 - from D01 to P13 32nd INTERNATIONAL GEOLOGICAL CONGRESS LANDSLIDES OF THE EMILIA APENNINES (NORTHERN ITALY) AUTHORS: G. Bertolini1, M. Pizziolo2 LEADER: G. Bertolini1 ASSOCIATE LEADERS: M.T. De Nardo2, G. Larini3, M. Pizziolo2 1Regione Emilia-Romagna, Servizio Tecnico dei bacini Enza e Sinistra Secchia - Italy 2Regione Emilia-Romagna, Servizio Geologico, Sismico e dei Suoli - Italy 3Regione Emilia-Romagna, Servizio Tecnico dei bacini Taro e Parma - Italy “DIREZIONE GENERALE AMBIENTE, DIFESA DEL SUOLO, DELLA COSTA E PROTEZIONE CIVILE. Servizio Geologico, Sismico e dei Suoli. Servizio Tecnico bacini Enza e sinistra Secchia” Florence - Italy August 20-28, 2004 Post-Congress P13 P13_R_OK A 25-05-2004, 13:26:31 Front Cover: The Morsiano landslide is the oldest among those dated in the Reggio Emilia Province. It formed from the Late-glacial to the Subboreal period, but several parts of it are still active today. P13_R_OK B 25-05-2004, 13:20:26 LANDSLIDES OF THE EMILIA APENNINES (NORTHERN ITALY) P13 Leader: G. Bertolini Associate Leaders: M.T. De Nardo, G. Larini, M. Pizziolo Introduction Even before the Landslide Inventory Map, the The Emilia-Romagna Region is one of the Regional Geological Survey was a national leader most landslide-prone territories in the world. in the study of landslides and their distribution. In Approximately 20% of the mountainous terrain is the 1980s a survey was performed for the 1:10.000- subject to the risk of landslides. scale regional geological cartography project. The Almost 99% of present-day landslide activity is due to detailed scale of this map allowed data from about the reactivation of pre-existing landslide bodies. 32.000 landslides to be collected. Under pressure Reactivation is a key-concept which must be from renewed public awareness, much work has been addressed. accomplished during the last decade. In addition, Since medieval times, 2000 villages in Emilia- events occurring in this time period have been studied Romagna have been built upon or very close to (a synthesis is found in Bertolini et al., 2001). A dormant landslides, despite the recurrent damage historical database of landslide events has been set which was infl icted upon some of them. up and some thousand records have already been After WW II, these villages expanded during the collected for the National Inventory of Landslides ensuing economic boom, without regard for such (IFFI) project. “minor” problems as landslides. This urban expansion continued into the 1970s and 1980s, when the climate The aim of the fi eldtrip is to show and explain was generally milder and landslide reactivation events experiences with landslides occurring within the infrequent. region. Geological and environmental conditions People, swept up by their new-found wealth, lost leading to instability will be described. Discussion some of their historical memory. Houses and factories will be encouraged especially regarding the role were built upon the fl atter, wider and apparently stable of mathematical modelling, cartography, historical portion of slopes …. which instead often turned out to research, monitoring and remote-sensing, as applied be the feet of dormant landslides! to landslide hazard evaluation. An awareness of landslides on the part of the regional administration, the media and the public, was fi nally References heightened in 1994 with the Corniglio landslide. This guide contains both original unpublished data This landslide was reactivated after one century of and references to recent publications. The main dormancy as it completely destroyed the hamlet of sources are: Linari (70 houses and industrial buildings). • Bettelli and de Nardo (2001) for the geological Since then, this region’s territory has been affected setting of marine units; several times (in 1996, 2000 and 2001) and some • Bertolini G. and Pellegrini M. (2001) for other hamlets have been either destroyed, severely historical data, radiocarbon dating and statistics damaged or threatened. about landslides; In Emilia-Romagna there have been no casualties, • Bertolini G., Canuti P., Casagli N., De Nardo but the economic costs and the repercussions upon M.T., Egidi D., Mainetti M., Pignone R. and industrial development have been heavy. The costs Pizziolo M. (2002) for cartography. of reconstruction and consolidation works have amounted to several hundreds of millions of Euros. A simple Glossary of Italian terms These costs have been entirely covered by the national Frana: how is it defi ned? Frana in Italian is a and regional governments. comprehensive term for any mass of rock, debris or DO1 to P13 n° 3 - from Volume In order to confront this problem, the Emilia-Romagna soil moving under the force of gravity, independent Geological Survey developed a new and detailed of the mechanism or the volume involved (sinkholes “Landslide Inventory Map” starting in the mid-1990s. are included). Frana is derived from the Latin noun This map is a powerful tool: it was immediately put to “frangina, ” which in turn is derived from the verb use in new territorial and urban planning. On the basis “frangere,” which means “to break.” of the new cartography, Emilia-Romagna became the The use of this term is widespread in all Italian fi rst Italian region to enforce rules and obligations regions, although several local dialect terms exist: addressing landslide hazard reduction. “lama,” “lezza,” “lavina”, “rovina,” and “ruina.” In 3 - P13 P13_R_OK 3 25-05-2004, 13:23:23 Leader: G. Bertolini P13 Volume n° 3 - from DO1 to P13 n° 3 - from Volume Figure 1 - Geological Map P13 - P13_R_OK 4 25-05-2004, 13:23:26 LANDSLIDES OF THE EMILIA APENNINES (NORTHERN ITALY) P13 particular, this last term is quite old: it was used in the Thetian basin closed due to continuous convergence written form in Dante’s “Divina Commedia” (Inferno, between the European and the Adriatic plates. First, XII, 4-9, 28-30) in reference to a large rockslide near in the Early-Middle Eocene, the subduction of oceanic Rovereto in the Adige Valley (“la grande ruina”). crust produced an accretionary prism of sediments. A list follows of the most commonly used specifi c After the oceanic crust was completely consumed, landslide classifi cations. But remember! Rarely is the ongoing collision between the two continents there a perfect correspondence between the Italian produced three broad allochthonous assemblages and English terms. The translations of Cruden & which correspond to three distinct paleogeographic Varnes’ defi nitions are not defi nitive and often are a domains (from internal to external): Ligurian, Sub- cause of endless debate! You can fi nd a more detailed Ligurian and Tuscan-Umbria-Romagna (Figure 1 discussion in Canuti & Esu, 1995. and 2). The Tuscan Units formed a fold-and-thrust belt which The more specifi c terms about landslide was then buried by the Ligurian and Sub-Ligurian classifi cation are: Nappes, both moving toward the NE. The Tuscan • referring to the landslide mechanism: Colata di Units are now partially exposed in a few tectonic terra (Mudslide, Mudfl ow), Colata rapida di windows (Mt. Zuccone, Gova, etc.) and on the ridge detrito (Debris fl ow), Scivolamento (Sliding), of the Apennine chain. Scivolamento traslativo (Translational slide), The relatively more allochthonous Ligurian Nappe Scivolamento rotazionale (Rotational slide), consists of the uppermost structural units and is Crollo (Fall), Ribaltamento (Toppling), well-exposed in the Emilian Apennines, from Smottamento (Land, Soil slip), Espansione Pavia to the Bologna Apennines. Its basal contact (Spread), Sprofondamento (Sinking); upon the Umbria-Romagna units is evident in • referring to the material involved: Suolo (Soil), outcrops along the transverse “Sillaro Line”. As a Terra (Earth), Detrito (Debris), Roccia (Rock), consequence of the Early-Middle Eocene closure of Substrato (Bedrock); the Ligurian oceanic basin, sediments which compose • referring to the state-of-activity: Attiva (Active), the semi-allochthonous “Epi-Ligurian sequence” Quiescente (Dormant), Inattiva (Inactive), were deposited in “satellite” basins, just above Sospesa (Suspended), Relitta (Relict). the Ligurian Nappe.