The devastating earthquake in Turkey on Feb. 6 has claimed the lives of more than 36,000 people and flattened thousands of buildings across southern Turkey and northern Syria.
Since the catastrophic event, Jonathan Stewart, a professor of civil and environmental engineering at the UCLA Samueli School of Engineering, has helped coordinate the U.S. response, including mobilizing a reconnaissance team that is now deployed to the region.
He also has been interviewed numerous times by journalists from around the world about the earthquake and its aftermath. Following are Stewart’s responses to some of the questions he has fielded. (The answers have been edited slightly for brevity and clarity.) Journalists and the public are welcome to share the information with attribution to Jonathan Stewart and the UCLA Samueli School of Engineering.
Is Turkey prone to having earthquakes?
Turkey frequently experiences major earthquakes. The country has two major faults with high levels of activity — the North Anatolian Fault and the East Anatolian fault. These faults are active because of plate movements on the surface of the earth, which is part of plate tectonics. The Arabian plate is moving north towards the Eurasian plate, which is squeezing a block of crust wedged between these to the west. The southern boundary of that block is the East Anatolian fault, on which the magnitude 7.8 event occurred.
Why were the aftershocks so strong following the earthquakes?
It is normal to have a high rate of aftershocks immediately after a large earthquake like the magnitude 7.8 event. The rate of aftershocks occurrence in time, and the size of the aftershocks in magnitude, should gradually decrease with time.
In the days since the earthquake, are there patterns you have observed among the buildings that collapsed? Do these failures point to specific construction flaws or the skirting of building codes?
We need to wait for data collected from on-the-ground inspections before drawing conclusions about specific patterns, but in past earthquakes, we have found that patterns for construction similar to those in this part of Turkey often reflect ground conditions — that is, certain conditions can amplify ground shaking intensities or produce liquefaction that affects a foundation’s performance.
In fact, we are expecting to see effects from liquefaction from this earthquake as broad portions of this area have shallow groundwater and geologically young soils. I think we’re also going to see major effects from the rupture of the fault at the ground surface across an extended length of approximately 200 kilometers, or 124 miles. Landslides in steep terrain are also likely.
We should know more in the next month or so as results from the work of reconnaissance teams become available.
Can earthquakes in the Middle East be predicted?
We cannot predict earthquakes on short time horizons, like days or weeks. We can predict areas that have relatively high or low levels of seismic hazard. The area that experienced [the Feb. 6] earthquakes is known to have high seismic hazard on Turkish national seismic hazard maps.
What improvements would you like to see as far as earthquakes are handled?
Improvements in building codes and their enforcement would be helpful for new structures. Older structures with known vulnerabilities should either be retrofitted or replaced.