Our thoughts for the earthquake victims in Turkey and Syria and a scientific reading of the earthquake

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Hearthquake in Turkey

Our Athenaeum expresses solidarity and sympathy to the people affected by the earthquake in Turkey and Syria. Our thoughts are with them in these terrible days. We asked Alessandro Maria Michetti, professor of Earthquake Geology and Seismic Risk in the Department of Science and High Technology who is currently engaged in excavations on Mount Etna, for a simple but scientific overview of what is happening.

Shortly after 4 a.m. local time (1:17 a.m. UTC) on Feb. 6, a strong 7.8-magnitude earthquake struck southern Turkey near the Syrian border. Not long after, an aftershock of magnitude 6.7 struck near the main quake. Several hours later, a magnitude 7.5 earthquake also shook the region. The relatively shallow depth of the main quake, close to 10 kilometers, caused strong ground accelerations over a large area of Turkey and Syria, as well as parts of Lebanon, Israel and Cyprus. Aftershocks are ongoing and will continue to shake the region for months, making the situation on the ground even more difficult to sustain. Macroseismic data are beginning to flow to Turkey's Civil Defense Agencies, AFAD.

The kinematics of the main quake have been left lateral (whichever side of the fault you are on, the other side has moved to the left). This is consistent with the movement of the East Anatolian Fault, which has a NE-SW direction and slip rates of between 6 and 10 millimeters per year. Turkey's other major fault system, the North Anatolian Fault, is right-lateral. Central Turkey is being squeezed westward between these two major faults, trapped in a tectonic vise, spilling into the Mediterranean Sea, toward Crete. This happens because Turkey is being pushed northward by the Arabian plate, and by the ongoing subduction in the eastern Mediterranean beneath the island of Cyprus.

Reports on the resentments of the event suggest that the shaking was most violent northeast of the epicenter, near the towns of Adiyman and Malaya. This indicates that the rupture was directional, propagating for hundreds of kilometers from SW to NE.

Thousands of casualties have already been confirmed in Turkey and Syria. Thousands of buildings throughout the region have collapsed, and rescuers are searching the rubble for survivors. Preliminary damage scenarios estimating casualties and economic losses from the strong earthquakes indicate that this tragic toll is most likely to increase. Economic losses in Turkey alone are to be estimated in the billions of euros. The devastation is widespread and is only now beginning to be discovered.

The epicenter of the Feb. 6 earthquake was near the city of Gaziantep in Gaziantep province. The province, along with neighboring Kahramanmaras province, is currently home to hundreds of thousands of Syrian refugees. It is cold and raining or snowing in much of the region, complicating matters for those whose homes have been destroyed or compromised. Authorities are warning residents not to return to damaged housing.

About nine hours after the Mw 7.8 magnitude earthquake, a Mw 7.5 earthquake followed, about 95 kilometers to the northeast. The location of the ruptures shows that it is the rupture of a different structure from the East Anatolian structure, conjugate to it, with E-W direction, known as the Sürgü-Çartak Fault. This is a typical mutual interaction between seismic sources, similar to but much more energetic than the one that produced the 2016 sequence of earthquakes in Central Italy (Amatrice Fault/M Monti della Laga, Monte Vettore Fault/Mount Bove).

Because it followed a larger earthquake in the same general region, the magnitude 7.5 event could be considered a tremor triggered by the main event. This means that if the magnitude 7.8 earthquake had not occurred, the magnitude 7.5 earthquake probably would not have occurred either. This is because it can be reasonably assumed that the first event promoted the second.

The major faults responsible for today's events show clear evidence of repeated lateral displacement over time during the Quaternary, over the past 2.6 million years; stream beds and alluvial terraces are displaced horizontally by tens of meters along the fault trace. Today, the main quake of Mw 7.8 caused an escarpment of a length in the order of 150 km, with an average displacement of about 3 m. It is the strongest earthquake in Turkey since 1939. It is also an unfortunately long-awaited earthquake in a region where the last events of this size date back several hundred years.

It is a similar situation to that of the Dead Sea Fault, which is the extension of the East Anatolian Fault southward, and runs through Syria, Lebanon and Palestine to the Gulf of Aqaba. Researchers from the Disat Geology Group recently published research on the segment of this fault that crosses Lake Tiberias, the subject of Maria Francesca Ferrario's postdoctoral investigations. There is a possibility that the Mw 7.8 earthquake will induce reactivations along other segments of the East Anatolian - Dead Sea Fault system, particularly in the sector between Syria and Israel, where events of this magnitude have been recorded historically but have been missing for hundreds of years.