Joint Reconnaissance EUCENTRE-ReLUis, Turkey-Syria Earthquake 2023 – Final report

Final report – Summary of the surveys (Pdf)

On May 9th to 12th , 24 technicians from Italian universities and centers of expertise and 11 technicians from METU or TED Universities in Ankara, carried out surveys on 204 school buildings (primary and secondary schools) located in the areas of Hatay, Maras, Antep and Adana provinces. Technicians were organized into 7 working groups inspecting the different areas. Out of the total 204 buildings, 190 buildings were fully inspected, while the remaining 14 buildings were found to have been demolished (10 buildings) or unified (4 buildings).
Fig.1 is shown the entire sample of buildings under study located within the seismic shake maps published by USGS related to: the event of February 6th, 2023 at 01:17:34 (UTC), magnitude Mw=7.8 (Fig. 1a), event of February 6th, 2023 at 10:24:48 (UTC), magnitude Mw=7.5 (Fig. 1b), event of February 20th, 2023 at 17:04:29 (UTC), magnitude Mw=6.3 (Fig. 1c). Fig.1d shows the distribution of inspected buildings, and the percentage, in relation to 8 PGA intervals, each of 0.1g amplitude. In that diagram, the maximum PGA inferred from the three shaking maps is taken as the reference PGA for each building.

In the attached report, a detailed overview of the appraised damage is reported.

Figure 1. – Positions of the inspected school buildings plotted against the PGA shake map of the Mw7.8 February 6th 2023 shock (a); the Mw7.5 February 6th shock (b); the Mw6.3 February 20th shock (c); number and percentage of buildings falling under each PGA interval (d).

After the inspection phase, a second phase of cataloging and data analysis is ongoing, which will be followed by a subsequent phase of more in-depth studies on individual cases to understand the seismic behavior of the surveyed buildings, focusing on the effectiveness of the implemented seismic retrofit techniques.
The field reconnaissance mission carried out in Turkey once again confirmed that the inspection and investigation activities following the occurrence of medium-high intensity seismic events represent an essential tool to understand the behavior of existing structures, for analysis and assessment of the related criticalities, and for the definition of future actions aimed at mitigating seismic risk.
Field experience is also essential for the growth and training of young technicians and for educating future generations on the importance of risk awareness and mitigation.

Working group ReLUIS – EUCENTRE, METU – TEDU, End-of-mission dinner.

4. Daily Report, May 12th 2023 (Pdf)

On May 12th, the last day of the field mission, 8 teams of technicians from Italian and Turkish universities and centers of expertise carried out site inspections on 53 school buildings (primary and secondary schools) located in the areas of the provinces of Hatay, Maras, Antep and Adana. These buildings add up to those seen in the previous days (43 on May 9th, 56 on May 10th, and 54 on May 11th) thus reaching a total of 206 inspected school buildings.
Figure 1 shows that on May 11th and 12th site inspections were carried out in the areas subject to higher PGA (on average, 0.54g and 0.47g), compared to the PGA of the areas surveyed in the first two days of inspections (on average 0.27g and 0.34g).

In the attached report, a detailed overview of the appraised damage is reported.

Figure 1. Positions of the school buildings inspected on May 9th‐10th‐11th‐12th (a,b,c,d); positions shown on the PGA shakemap of the M7.8 shock of February 6th 2023, provided by the USGS (e); percentage of the school buildings inspected each day, belonging to 0.1g wide PGA intervals.

Report and photographic material: earthquake damage on the case study school buildings
This section contains a brief description of the more noteworthy types of damage encountered in the more heavily damaged buildings inspected on May 12th.

• KAYMAKAM HASAN ZENGİNALP İLKOKULU

Figure 2. Prospect view of the building exhibiting widespread damage (no documented pre‐earthquake retrofit).

Report and photographic material: earthquake damage on residential buildings
In the urban areas surrounding the buildings under inspection, various damage patterns and failure mechanisms were observed in residential (and other) buildings. Some noteworthy examples are presented here.

• City of Antioch (Antakya)

Figure 3. Damage state of a stone masonry building in the historic city‐center of Antioch: collapse of the roof, inplane and out‐of‐plane failure mechanisms of the masonry walls. The cantilevers of the balconies overlooking the main entrance have survived, oddly enough.

• City of Kirikhan
Damage was encountered in a residential building in downtown Kirikhan, visible on the right‐hand side of Figure 10, where one can observe a floor‐sway failure mechanism on the first two elevations of the left portion of the building and partial pancake collapse on the right portion. On the left‐hand side of the picture, a mosque is visible, with evident damage on the external front walls, in the form of shear cracks and an apparent deviation from the vertical position of the minaret, which does not seem to have suffered other serious damage.

Figure 4. Residential complex in downtown Kirikhan.

3. Daily Report, May 11th 2023 (Pdf)

On May 11th, 8 teams of technicians organized into 7 working groups, each of which supported by a technician from the METU or TED Universities of Ankara, carried out site inspections on 54 school buildings (primary and secondary schools) located in the provinces of Hatay, Maras, Antep and Adana. These buildings are added to those viewed in the previous days (43 on May 9th and 56 on 10 May 10th) thus reaching a total of 153 buildings.
Figure 1a shows the entire sample of buildings under study and their location on the seismic shake map of the Feb. 6th earthquake published by USGS. Figure 1b shows the distribution of both the entire sample of buildings and the 54 buildings inspected on May 11th with reference to PGA intervals of amplitude 0.1g. Figure 1b shows that the subset of buildings inspected today constitutes a large part of the buildings in the areas with the higher acceleration ranges.

Figure 1. Position of the school buildings, inspected by the seven groups, in overlay against the PGA shakemap of the M7.8 shock of February 6th provided by the USGS (a); frequency distribution of the school buildings with respect to 0.1g wide PGA intervals (b).

• In the attached report, a detailed overview of the appraised damage is reported (Pdf).

2. Daily Report, May 10th 2023 (Pdf)

On May 10th, 8 teams of technicians organized into 7 working groups, each of which supported by a technician from the METU or TED Universities of Ankara, carried out site inspections on 54 school buildings (primary and secondary schools) located in the provinces of Hatay, Maras, Antep and Adana. The 7 groups inspected 56 schools. In addition to the damage level, it was possible to obtain information relating to the year of construction, the year of design of the reinforcement intervention as well as the type of intervention carried out on each school building.
In the attached report, a detailed overview of the appraised damage is reported.

Figure 1. REYHANLI LİSESİ OKUL+İDARİ BİNASI: Partial collapse of the roof cover.

• Scuola DR. MUSTAFA GENÇAY ILKOKULU

Figure 2. DR. MUSTAFA GENÇAY ILKOKULU: Left panel: front view; right panel: view from the inside, collapsed external infill masonry walls and plastic hinging of the adjacent columns with clear disorganization of the concrete nucleus due to lack of adequate passive confinement.

Figure 3. Antiochia: Partial collapse of a large portion of a dormitory building, due to heavy damage of several consecutive columns at t the ground floor.

Figure 4. Atakoy: Shear failure of several RC columns near the stairwells.

1. Daily Report, May 9th 2023 (Pdf)

The Civil Protection Department has promoted an important technical-scientific activity in the areas affected by the earthquakes that occurred in Turkey and Syria starting from 6 February this year, with a maximum magnitude of 7.8. In this context, two missions have been organised, one aimed at investigating the effects of the earthquake from a geological and seismological point of view and one aimed at investigating the structural response of the building stock.
The two engineering competence centers RELUIS and EUCENTRE, in collaboration with METU and TEDU Universities of Ankara, are carring out the damage reconnaissance.
The activity, agreed with the Turkish civil protection (AFAD), follows the agreements of a first mission in Ankara on April 24th-26th coordinated by the Italian Civil Protection Department, and is aimed at the evaluation of earthquake effects on public buildings (schools, barracks, municipal offices, etc…) on which reinforcement interventions were planned and/or carried out before the seismic event of 6 February.
In agreement with a delegation of researchers from the METU and TED Ankara Universities, more than 200 buildings have beeb selected in the provinces of Hatay, Maras, Antep and Adana.
The location of these buildings is reported on the shakemap published by the USGS following the Februry 6th event, as shown in Figure 1a.

Figure 1. Geographic localisation of buildings overlapped to Shakemap of the 6th February earthquake by USGS (a); magnification on subset of buildings inspected on May 9th (b).

On May 9th, 8 teams of technicians from various Italian Universities (Univ. degli studi di Palermo, Univ. del Salento, Univ. degli studi della Basilicata, Univ. degli studi di Napoli Federico II, Univ. di Genova, Univ. di Bologna, Univ. degli studi di Pavia) and the EUCENTRE competence centre carried out inspections on 45 school buildings (primary and secondary schools) located in the city of Iskerenderun (Alessandretta), where maximum recorded accelerations according to the USGS ShakeMap were in the range 0.18-0.24g (see Fig. 2b). The buildings inspected were reinforced concrete (r.c.) structures characterised by two-way frames. In most cases, strengthening interventions had been carried out before the seismic event of February 6th.

Figure 2. Group photo of the 8 teams of ReLUIS, EUCENTRE, METU, TED technicians; and some of the school buildings inspected on May 9th.

The inspections showed that the buildings surveyed are characterised by a number of above-ground floors mostly between 2 and 4, regular in plan and elevation, built in most cases between the late 1950s and the late 1970s. In some cases, further structural units had been built since the 1980s, connected to the original structure by means of expansion joints. In all the buildings, seismic retrofit interventions were implemented mostly through the insertion of r.c. walls within the structural grid, in both directions, and the consolidation of foundations. The buildings inspected showed a moderate level of overall damage, mostly concentrated in the joint areas due to pounding of adjacent structural units (see Figure 3).

Figure 3. Photos of damage due to pounding: slight (a), moderate (b), severe (c).

The load-bearing structures did not suffer major damage; however, in several buildings, damage was observed at the interface between the original r.c. frame and the r.c. wall adopted as the reinforcement system. It turned out that the r.c. walls were built by removing a partition/infill panel and replacing it with a r.c. wall connected to the existing frame. The anchoring of the wall to the frame was evidently ineffective as evidenced by the state of damage shown in Figure 4.
During the inspections in the city of Iskerenderun (Alexandretta), a more severe level of damage was observed on average on residential buildings compared to the inspected school buildings, the subject of the current activity. Figure 5 and Figure 6 show, for two r.c. buildings, some emblematic damage cases related to the development of a soft-storey mechanism and a shear crisis due to the interaction with the infills.

Figure 4. Detachment at the interface between the original r.c. frame and the wall adopted as strengthening system.

Figure 5. Brittle shear failure of a r.c. column due to interaction with infills.

Figure 6. Very severe damage on a r.c. building due to soft-storey mechanism.