EERI-LFE Advance Reconnaissance Team Observations of Earthquake Impacts in Turkey

 On February 6, 2023, a pair of earthquakes (Mw 7.8 and 7.5, USGS) struck south/southeastern Turkey. During February 15-20, 2023, an EERI Learning From Earthquakes advance team conducted field visits in the disaster zone. The field team included Ayse Hortacsu (M.EERI 2000) from the Applied Technology Council and Ayhan Irfanoglu (M.EERI 1994) from Purdue University, along with Prof. M. Altuğ Erberik from the Middle East Technical University (ODTU) and M. Fırat Aydın from the TED University. We are grateful for their support and companionship.

The field visits took place in the second week following the main shocks. Aftershocks were frequent, limited rescue operations were still ongoing, and damage assessment and demolition efforts were very active. Most residents of areas with high damage were living in tent cities or had traveled out of town, leaving almost all residential units empty, even those assessed to have low damage.

turkey earthquake hazard map

The team traveled over 1,500 km in the regions affected by the disaster in Turkey, first along a north-to-south path, and then east-to-west in the southern third of the region. The team made stops at the following towns:

Day 1: Elbistan, Nurhak, Gölbaşı, Pazarcık, Narlı, Gaziantep
Day 2: Kahramanmaraş, Türkoğlu, Nurdağı
Day 3: İslahiye, Hassa, Kırıkhan, Antakya
Day 4: Erzin, Dörtyol, İskenderun, Arsuz
Days 5 & 6: Adana, Osmaniye, Bahçe

Numerous fatalities and extensive damage in northern Syria have been reported. Unfortunately, the EERI-LFE team was not able to travel to the disaster zone in Syria.

earthquake zone turkey

The team made drive-by observations of the damage to private and public buildings along the main roads as well as close range observations in the areas where they stopped for on-foot reconnaissance. Observations included residential buildings of various kinds where casualties and damage primarily occurred, from 3-7 story low-rise older (built before the 1998 code) to 8-20 story mid-rise newer reinforced concrete buildings, and 1-2 story adobe or brick buildings with vernacular architecture. The team also took note of performance of hospitals and school buildings, new and old, in the region. Information regarding disaster response was gathered either through direct observation or through talking to locals, including a hospital chief in Kahramanmaras and an NGO involved with disaster aid distribution based in Iskenderun.

A vast network of strong ground motion recording stations, part of the Turkish Accelerometric Database and Analysis System managed by the Disaster and Emergency Management Presidency (AFAD), Ministry of Interior, Republic of Türkiye, exists in the region. The first event caused intense ground motions over a vast area. Around 50 stations registered motions giving peak ground velocity (PGV) over 30 cm/s and with peak ground acceleration in the range of 0.2g to 1.4g. Nearly 15 stations recorded motions indicating PGV ~100 cm/s to ~200 cm/s and PGA ~0.3g to ~1.4g.

Most of the area seen by the EERI-LFE advance team were in this PGV > 30 cm/s ground motion zone, with towns straddling the causative fault zone having PGV > 80 cm/s and up to nearly 200 cm/s.

The extent of the damage varied between towns. Overall, older (pre-1998) low to mid-rise reinforced concrete (RC) buildings fared far worse than any other building type, with numerous collapses or heavy damage (e.g., in Antakya and the provincial capital of Kahramanmaraş). Some of the key issues were the presence of soft ground stories (due to taller ground story and/or open floor plan of the ground story used as shops), poor detailing of the structural members and their connections, and possibly detrimental interaction between columns and infill walls. RC buildings constructed in the last two decades tended to be taller (mostly in the 10-15 story range, but several 20-25 story high buildings were seen). Proportionally fewer collapses were observed in these post-1998 mid-rise RC buildings. Still, there were towns with a majority of such newer buildings and with heavy damage to their structural elements (e.g., Nurdağı, Kırıkhan) or to their infill walls (e.g., northern part of Antakya, Elbistan, Adana). There were numerous modern buildings with their perimeter infill walls collapsed out-of-plane, exposing building interiors fully all the way up to 4th or 5th story.

antakya lfe team

Non-engineered 1-2 story buildings appeared to have fared proportionally well, be they in the countryside along the roads traveled by the LFE team or in the outskirts of major towns. Buildings on lowlands performed much worse than similar construction on hillsides (e.g., Kahramanmaraş) even though the building types were similar. Clearly ground motions were different.

School buildings performed relatively better. Among older (pre-1998) school buildings seen, one had a story collapse (in Kahramanmaraş's downtown) and another one had signs of initiation of severe damage (in Arsuz). Post-1998 school buildings appear to have performed very well. Other government buildings, such as administrative offices, were also observed to have performed relatively well compared to residential construction.

Hospital buildings appeared to have performed well, structurally, but many of them were observed to be non-functional and offering services in tents set up in the parking lot (e.g. Kahramanmaraş, Türkoğlu, Hassa, Erzin). A private hospital in Kahramanmaraş had structural damage and was out of commission. Several field hospitals and mobile pharmacies were seen. In recent years, several new large-scale hospitals have been built, or under construction, in which base-isolators are used. One such hospital, in Kahramanmaraş, was visited by the LFE advance team. Even though this hospital was under construction at the time of the earthquake with the isolators locked for construction, the locks broke during the first earthquake and the building responded well. The existing, non-isolated 2010-built wing of the hospital had ceiling panel failures, fire in the control room, and a localized and practically immaterial beam-column connection failure due structural detailing issues. Unfortunately these, and the failure of off-site water supply tanks, rendered the hospital nonfunctional. A field hospital was set up next to the hospital. Another base-isolated hospital in Dörtyol appeared to be fully functional.

kahramanmaras hospital

Severe damage to or collapse of mosques were observed only in areas of widespread damage, as in Kırıkhan and Islahiye, including the historic Habib-i Neccar mosque in Antakya. Additionally, a historic church was assessed to have sustained heavy damage in İskenderun.

Roads were, by and large, intact and usable, but with caution in the vicinity of causative fault zones. Rockslides were observed both on motorways and the railroad between Elbistan and Gölbaşı. Excessive damage, deformations in roadways and bridge approach ramps were seen between Elbistan and Gölbaşı, in Gölbaşı, Türkoğlu, Nurdağı, and Islahiye.

Small and large tent cities were set up in all larger towns. Mobile soup kitchens, bank services, and cellular towers were seen. We were told that the needs had changed over time: for the first few days, drinking water was scarce but by week one, supplies were sufficient. Blankets were sought initially, but later sleeping bags were asked for. Tents were always in high demand. We were told that pallet-loaded supplies on flatbed (exposed or soft-covered) tractor trailers were an order of magnitude faster and easier to unload when compared to container-style or individually packaged non-pallet supplies.

Earthquake Engineering Research Institute
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Oakland, CA 94612
Phone: 510-451-0905
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