Survey of churches damaged by the 2012 Emilia-Romagna earthquake sequence

Survey of churches damaged by the May 2012 Emilia-Romagna earthquake sequence Paupério, E.1, Romão, X.2, Tavares, A.3, Vicente, R.4, Guedes, J.5, Rodrigues, H.6, Varum, H.7, Costa, A.8 1 Construction Institute, Faculty of Engineering of the University of Porto, Porto, Portugal; [email protected] 2 Faculty of Engineering of the University of Porto, Porto, Portugal; [email protected] 3 Faculty of Engineering of the University of Porto, Porto, Portugal; [email protected] 4 University of Aveiro, Aveiro, Portugal; [email protected] 5 Faculty of Engineering of the University of Porto, Porto, Portugal; [email protected] 6 University of Aveiro, Aveiro, Portugal; hr[email protected] 7 University of Aveiro, Aveiro, Portugal; hv[email protected] 8 University of Aveiro, Aveiro, Portugal; [email protected] Cite as: Paupério, E., Romão, X., Tavares, A., Vicente, R., Guedes, J., Rodrigues, H., Varum, H., Costa, A. (2012) Survey of churches damaged by the 2012 Emilia-Romagna earthquake sequence. Faculty of Engineering of the University of Porto and University of Aveiro, Portugal. Available at https://dl.dropbox.com/u/8147292/FEUP_UA_Emilia-Romagna_earthquake_report.pdf 2 Table of Contents 1. Introduction .......................................................................................................................................................................................................... 2 2. Brief review of the 2012 Emilia-Romagna earthquake sequence ........................................................................................................................ 2 3. Context of the presented church damages ............................................................................................................................................................ 4 4. General characterization of the churches surveyed .............................................................................................................................................. 8 5. Emergency interventions ...................................................................................................................................................................................... 19 Acknowledgements ................................................................................................................................................................................................. 20 References ............................................................................................................................................................................................................... 20 Church damage worksheets ...................................................................................................................................................................................... 22 3 1. Introduction This report presents an overview of the damage that was observed in fourteen churches that were hit by the May 2012 Emilia-Romagna earthquake sequence. The data was collected over the course of a two-day reconnaissance mission that took place on the 9th and 10th of July 2012, and that involved researchers from the Civil engineering Department of the Faculty of Engineering of the University of Porto and of the University of Aveiro, both institutions from Portugal. It is noted that the current report only focusses the post-seismic damage assessment of churches and does not address the cultural and artistic losses associated to movable or immovable heritage. Furthermore, it is also referred that since the reconnaissance mission took place after the major earthquakes of the 20th and the 29th of May, the source of the reported damages is not assigned to a particular event and must be seen as the cumulative effect of several ground motions. 2. Brief review of the 2012 Emilia-Romagna earthquake sequence On the 20th of May 2012, at 04:04 (local time), a magnitude Mw = 5.9 earthquake hit the Emilia-Romagna region of northern Italy. The epicentre was found to be approximately 30km northwest of Ferrara (Fig. 1) and the depth of the hypocentre was found to be around 6km. The focal mechanism indicates that the earthquake was a result of thrust faulting, with a north-south direction of compression, on a fault plane trending west-east (USGS, 2012). This earthquake resulted in 7 deaths, significant damage to historical constructions, churches and industrial buildings. The 20th of May event was followed by several aftershocks, namely two with a magnitude Mw higher than 5.0 on the same day. On the 29th of May 2012, at 09:00 (local time), a magnitude Mw = 5.8 earthquake hit the same region. The epicentre of this new event was determined to be approximately 40km west of Ferrara, around 15km southwest of the epicentre of the 20th May event (Fig. 1), and the depth of the hypocentre was found to be around 10km. This earthquake had a similar mechanism to that of the 20th May event. This new earthquake caused further damage to the locations hit by the 20th May earthquake and extended the affected area to the East-side of the province of Modena. This event resulted in another 17 deaths and increased the level of damage of the historical constructions, churches and industrial buildings already weakened by the 20th May event. The 29th May event was followed by several aftershocks, namely three with a magnitude Mw higher than 5.0, two on the same day and another on June 3. According to data from the Italian Istituto Nazionale di Geofisica e Vulcanologia, peak ground accelerations of around 0.30g were recorded in the vicinity of both epicentres (INGV, 2012). 4 a) b) Fig. 1 – Location of the epicentres of the main events of the Emilia-Romagna earthquake sequence: general overview (a); detailed view (b): E1) earthquake of the 20th May, E1a) aftershocks of the 20th May earthquake with magnitude Mw > 5.0, E2) earthquake of the 29th May, E2a) aftershocks of the 29th May earthquake with magnitude Mw > 5.0. 3. Context of the presented church damages The damage assessment that was carried out on fourteen churches surveyed during the reconnaissance mission is presented in the following. The churches that were surveyed are presented in Table 1 and their location relative is represented in Fig. 2. E1 E2 E2a E1a 5 Table 1 – Churches surveyed. Reference number Name Location Undamaged church Reference number Name Location Undamaged church I1 Cathedral of San Paolo Mirabello I2 Oratorio Ghisilieri San Carlo I3 Church of San Martino Buonacompra I4 Church of San Lorenzo Casumaro Finalese I5 Church in Bondeno Bondeno I6 Church of Sacro Cuore Bondeno I7 Church of San Geminiano Vescovo Massa Finalese I8 Church of Santa Maria Maggiore Mirandola 6 Table 1 (continued) – Churches surveyed. Reference number Name Location Undamaged church Reference number Name Location Undamaged church I9 Church of San Francesco Mirandola I10 Church of SS Apostoli Giacomo e Filippo San Giacomo di Roncole I11 Church of Montalbano Montalbano, Medolla I12 Church of Cavezzo Cavezzo I13 Church of San Nicola di Bari Cortile, Carpi I14 Cathedral of Santa Maria Assunta Carpi 7 Fig. 2 – Location of the churches surveyed with respect to the main events of the Emilia-Romagna earthquake sequence. The surveys are presented in the form of visual damage report worksheets that are included in the end of this report. For churches that were more heavily damaged, the damage report worksheets only present the more significant damages. The damage report worksheets also include additional information such as:  The church identification (name, location, GPS coordinates)  The period of construction of the church  The main dimensions of the church (and of the tower if it exists)  The materials of the main construction elements  The type of access that was available for the survey  The overall damage state of the church  The type of emergency interventions that were already in place (if any) Aside from a few exceptions, the surveys were generally performed from the exterior. Therefore, the presented damage levels should be seen as mainly qualitative. The damage grading was carried out for all the churches using the list of damage types presented in Table 2. The Italian postI1 I2 I3 I7 I5 I4 I6 I10 I8 I9 I11 I12 I13 I14 E1 E2 8 earthquake damage survey form, e.g. see Lagomarsino (2012), and its corresponding list of damage mechanisms, was not considered in this analysis due to difficulties in identifying such mechanisms as the result of two aspects:  The available access for the survey was rather limited in most cases.  The level of damage exhibited by most churches results from the cumulative effect of more than one major earthquake event. Table 2 – List of considered damage types. Damage type Damage number Cracking D1 Collapse of the facade (partial or total) D2 Collapse of the roof/vaults (partial or total) D3 Collapse of walls (partial or total) D4 Out-of-plane detachment of walls D5 Detachment of the outer layer of masonry D6 Masonry crushing at the tie rod anchorage D7 Masonry crushing in compression D8 Pounding D9 Fall of spire (facade/tower) D10 Collapse of the tower (partial or total) D11 Collapse of reinforced concrete elements D12 For each church, only the more important damage types are reported, based on the in situ observations. The intensity of each damage type was then graded as Low, Medium or High. Based on the individual grading of the damage types, the global state of damage of each church was also graded as Low, Medium or High. 4. General characterization of the churches surveyed The churches and towers surveyed are mostly made of brick masonry. The different brick masonry bonds of the masonry walls that were observed among the existing debris of some of the churches are presented in Figs. 3 to 8. The bond type of Fig. 3 represents an example of single 9 header bond masonry along with the corresponding sketch of the bond type according to Borri (2006). The block dimensions of this wall are 28 14 3 5. cm according to in situ measurements. a) b) c) d) Fig. 3 – Single header brick masonry bond in church I2: general view (a), detail (b) and sketch of the bond type adapted from Borri (2006) (c), brick dimensions in cm. The bond type of Figs. 4 and 5 is a double header bond masonry similar to the Flemish bond and was observed in churches I1 and I3. Figure 4 also presents a sketch of the bond type according to Borri (2006) and a sketch of the cross section view of the wall. In this case, the brick dimensions were not able to be measured. In church I1, it was also observed that the region of the timber truss supports was reinforced by duplicating the wall, Figs. 5b) and c). Although it was not able to be observed, it is believed that both walls must be connected to the truss by timber or metallic elements. 28 14 3.5 16 a) b) c) d) Fig. 13 – Examples of reed mat false vaults in churches I2 (a) and I10 (b) and (c), and detail of a reed mat (d). 17 Fig. 14 – Example of a vault made of timber elements imbedded in mortar/plaster in church I11. With respect to the arches, those that were able to be observed were made of vertically stacked brick masonry (Fig. 15). The interior columns that were surveyed were also seen to be made of brick masonry (Fig. 16). Fig. 15 – Examples of arches made of vertically stacked brick masonry in church I1. 18 Fig. 16 – Example of an interior column made of brick masonry in church I1. Finally, it is also referred that in church I1, the debris of a collapsed reinforced concrete element were found. The debris are believed to be part of a large reinforced concrete beam that existed over the transept area (Fig. 17). As can be seen, the beam reinforcement was made of smooth rebars and the transverse reinforcement was almost inexistent. It is also noted that the beam appeared to be supported by the brick masonry walls. Fig. 17 – Collapsed reinforced concrete beam in church I1. 19 Whenever possible, general dimensions of the churches and towers were measured (Fig. 18). However, since the surveys were performed from safe positions, such dimensions should be considered to be approximate. Additional measures and data were also obtained from Decanini et al. (2012), Ioannou et al. (2012) and Rossetto et al. (2012). Fig. 18 – Examples of general dimension surveys carried out for the churches and towers. 5. Emergency interventions With respect to the emergency interventions that were observed in some of the churches, these were grouped according to the typologies presented in Table 3. Nonetheless, information was also obtained regarding some churches in which elements were either removed or demolished for safety reasons. For example, it was found that the tower of church I3 was demolished after the 20th May earthquake while the spire of the tower adjacent to church I1 was removed from its location also after the 20th May earthquake. 20 Table 3 – List of considered emergency intervention types. Emergency intervention type Emergency intervention number Steel raker shoring of walls i1 Wood raker shoring of walls i2 Wood shore at the openings i3 Confinement of the facade with steel cables i4 Confinement of the tower i5 Confinement of the frontispiece with polyester-nylon strips i6 Confinement of the spire with polyester-nylon strips i7 Acknowledgements The authors would like to thank the financial support of the Portuguese Foundation for Science and Technology and the Centro de Estudos da Construção research centre of the Civil Engineering Department of the Faculty of Engineering of the University of Porto for sponsoring their participation in this reconnaissance mission. The authors would also like to thank don Giancarlo Mignardi, priest of the church of San Carlo, for the information provided and Manuel Carvalho for his help in preparing the church damage report worksheets. References Borri, A. (2006) Allegato 3b.1_UR06_2. Progetto di recerca Nº1, Valutazione e Riduzione della Vulnerabilità di Edifici in Muratura, Rendicontazione Scientifica 1º anno. Rete dei Laboratori Universitari di Ingegneria Sismica (RELUIS). Decanini L.D., Liberatore D., Liberatore L., Sorrentino L. (2012) Preliminary report on the 2012, May 20th, Emilia earthquake. v.1. Available at http://www.eqclearinghouse.org/2012-05-20-italy-it/ (Accessed July 2012). INGV (2012) Istituto Nazionale di Geofisica e Vulcanologia. Available at http://terremoti.ingv.it/it/ultimi-eventi/842-terremoti-in-pianurapadana-emiliana.html (Accessed July 2012). 21 Ioannou, I., Borg, R., Novelli, V., Melo, J., Alexander, D., Kongar, I., Verrucci, E., Cahill, B., Rossetto, T. (2012) The 29th May 2012 Emilia Romagna Earthquake. EPICentre Field Observation Report No. EPI-FO-290512. Available at http://www.eqclearinghouse.org/2012-05-20-italyit/ (Accessed July 2012). Lagomarsino, S. (2012) Damage assessment of churches after L’Aquila earthquake (2009). Bulletin of Earthquake Engineering 10(1), 73-92. Rossetto, T., Alexander, D., Verrucci, E., Ioannou, I., Borg, R., Melo, J., Cahill, B., Kongar, I. (2012) The 20th May 2012 Emilia Romagna Earthquake. EPICentre Field Observation Report No. EPI-FO-200512. Available at http://www.eqclearinghouse.org/2012-05-20-italy-it/ (Accessed July 2012). USGS (2012) M 6.0, 5.8, and 5.4 Northern Italy Earthquakes of May 2012. ftp://hazards.cr.usgs.gov/maps/sigeqs/20120529/20120529.pdf (Acessed July 2012).