Complexities of the Turkey-Syria doublet earthquake sequence

Abstract

In the early morning of February 6th, 2023, an M7.8 earthquake occurred in southeastern Türkiye near the northern border of Syria. The event initiated a complex sequence of aftershocks, including an M7.6 earthquake about 9 h later and 90 km to the north (Figures 1A and 1B). The earthquake sequence is also referred to as a strong doublet earthquake sequence. Aftershocks of the two strong earthquakes occurred along two separate branches of the East Anatolia Fault, with lengths of up to 300 km, and some aftershocks occurred in Syria (NEIC/USGS, 2023). The earthquake sequence caused significant losses to Türkiye and Syria, including over fifty thousand human lives and tens of billions of US dollars in damage to the economy, social infrastructure, and valuable historical sites,1 along with abundant evidence of surface ruptures, ground deformation and liquefied soils. The earthquake sequence also triggered extensive subaerial landslides, with about 100 identified by NASA from Planet Lab's high-resolution satellite imagery, including several in the valley near Sarıseki. Very strong ground motion was observed at station 3126 in Antakya during the M7.8 earthquakes (Figure 1D), with horizontal acceleration greater than 1 g (normal gravitational value).

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