Jiannan Meng

The February 6, 2023 earthquake sequence in eastern Türkiye stands as one of the most catastrophic seismic events of the past century. This study presents high-resolution (centimeter-scale) drone maps of surface ruptures recorded 10 days after the event. Our dataset includes the complete rupture of the Narli segment along the Dead Sea Transform Fault, responsible for the initial Mw 7.8 earthquake, and detailed mapping of three additional rupture sites along the East Anatolia Fault Zone.These geo-referenced maps and ground offset data reveal that the earthquake sequence commenced along the Dead Sea Transform Fault, induced by the northward displacement of the Arabian Plate. This movement subsequently triggered the slip along the East Anatolia Fault, which had accumulated significant tectonic stress. The rupture transferred both sides of the fault, resulting in extensive structural damage. The subsequent Mw 7.5 earthquake along the Çardak-Sürgü Fault, occurring nine hours later, was triggered in the same way, after a Mw 4.5 event at the intersection of the East Anatolian and Çardak-Sürgü Faults.En echelon fracture patterns are the most common surface deformation style along all the fault zones regardless of the base rock and topography, cut basins and ridges directly instead of always following the pre-existing weak surfaces. The biggest surface offset is at the intersection of the Dead Sea Transform Fault and the East Anatolia Fault, 47.5 kilometers from the epicenter, suggesting that the surface rupture is the result of long-term accumulated stress release along the fault system, triggered by one earthquake event caused by plate motion.Our findings offer vital insights into surface deformation features of continental strike-slip earthquakes, elucidate rupture propagation mechanisms, and shed light on the interaction and slip transfer between complex fault systems within a contemporary continental collision zone. These observations contribute to a deeper understanding of how those displacements accommodate plate motions and ”displace“ human beings at the same time.

The powerful earthquake that struck eastern Türkiye on February 6th 2023 is the most devastating earthquake of the past century in the region. Here we present our first-hand field measurements of the ground offsets and the high resolution (centimeter level) drone-mapped surface ruptures 10 days after the first shock. It is clear that the initial rupture was on the Dead Sea fault zone (DSFZ), yet maximum displacements and energy release (Mw 7.8) occurred 24 sec later when rupture transferred to the East Anatolian fault zone (EAFZ). Seven hours later, a Mw 4.5 aftershock at the junction of the EAFZ with the east-west striking Çardak-Sürgü fault (Ç-SF) triggered the second large (Mw 7.5) earthquake, causing another round of the damage in the region. The maximum ground offsets are around 47.5 kilometers away from the epicenter in this event on the EAFZ. The surface ruptures directly cut young basins and mountains, as well as activating some pre-existing surfaces. Our observation provides important data on surface deformation during large continental strike-slip earthquakes, rupture propagation mechanisms, and how slip may be transferred between complex fault systems. We also provide insight into how slip along linked fault systems accommodates global plate motions.

Two powerful earthquakes struck Türkiye on 6 February 2023. The initial rupture was on the Dead Sea fault zone, yet maximum displacements and energy release [moment magnitude ( M _w ) 7.8] occurred 24 seconds later when rupture transferred to the East Anatolian fault zone (EAFZ). More than 7 hours later, a M _w 4.5 aftershock at the junction of the EAFZ with the east-west striking Çardak-Sürgü fault was followed 86 minutes later by the second large ( M _w 7.5) earthquake, suggesting a causal relationship. We provide quantitative ground and aerial documentation of surface offsets and kinematics from the slipped faults, providing important data on surface deformation during large continental strike-slip earthquakes, rupture propagation mechanisms, and how slip may be transferred between complex fault systems. We also provide insight into how slip along linked fault systems accommodates global plate motions.

A devastating M 7.0 earthquake on October 30, 2020, offshore Samos Island, Greece, was a consequence of the Aegean and Anatolian upper crust being pulled apart by north-south extensional stresses resulting from slab rollback, where the African plate is subducting northwards beneath Eurasia, while the slab is sinking by gravitational forces, causing it to retreat southwards. Since the retreating African slab is coupled with the overriding plate, it tears the upper plate apart as it retreats, breaking it into numerous small plates with frequent earthquakes along their boundaries.  The earthquake happened offshore of the extensional Büyük Menderes Graben, where a 150 km long, 10 km wide, incipient upper plate rift system formed in the Anatolian plate, showing that the entire Aegean-Western Anatolian region is being pulled apart by extensional stresses related to the slab rollback. Earthquake solutions and fault plane studies around western Anatolia support this spectacular extension, and show that the modern extension was preceded on many faults by oblique extension and strike-slip motions, perhaps reflecting a change in tectonic setting from sideways escape from the Africa-Arabia collision with Eurasia,  to the pure extension related to slab rollback of the African plate, and the retreat of the Hellenic trench. Historical earthquake swarms and deformation of the upper plate in the Aegean have been associated with massive volcanism and cataclysmic devastation, such as the M 7.7 Amorgos earthquake in July 1956 between the islands of Naxos and Santorini (Thera). Even more notable was the eruption of Santorini 3650 years ago, which contributed to the fall of the Minoan civilization. The Samos earthquake highlights the long historical lack of appreciation of links between deep tectonic processes and upper crustal deformation and geological hazards, and is a harbinger of future earthquakes and volcanic eruptions, establishing a basis for studies to institute better protection of infrastructure and upper plate cultures in the region. Further detailed studies are needed in this area to better understand and predict earthquake frequency, possible locations, and to establish better building codes to protect people's lives and property.