Rapid 3D dynamic rupture modeling of the February 6, 2023, Kahramanmara\c{s}, Turkey, $M_W$7.8 and $M_W$7.7 earthquake doublet

TL;DR

This paper presents rapid 3D dynamic rupture simulations of the 2023 Turkey earthquake doublet, providing timely, physically consistent explanations for complex rupture behaviors and ground motions based on limited early observations.

Contribution

It introduces a rapid modeling approach that integrates regional tectonics and heterogeneous fault properties to interpret complex earthquake rupture dynamics shortly after the event.

Findings

Models match geodetic and seismic data for both events.

Delayed backward branching explained without supershear speeds.

Heterogeneous fault properties account for rupture asymmetry.

Abstract

The 2023 Turkey Earthquake sequence involved unexpected ruptures across numerous fault segments, challenging data interpretation efforts. We present rapid, 3D dynamic rupture simulations to illuminate the complexities of the $M_W$7.8 and $M_W$7.7 earthquake doublet. Constrained by observations available within days of the sequence, our models deliver timely, mechanically consistent explanations for the unforeseen rupture paths, diverse rupture speeds, multiple slip episodes, locally strong shaking, and fault system interactions. We reconcile regional seismo-tectonics, rupture dynamics, and ground motions of a fault system represented by ten curved dipping segments and a heterogeneous stress field. Our simulations link both events matching geodetic and seismic observations. The $M_W$7.8 earthquake features delayed backward branching from a steeply intersecting splay fault, not requiring supershear speeds. The asymmetrical dynamics of the distinct, bilateral $M_W$7.7 event is explained by heterogeneous fault strength, prestress orientation, fracture energy, and static stress changes from the previous event. Our models explain the northward deviation of its western rupture and the minimal slip observed on the S\"urg\"u fault. Rapidly developed 3D dynamic rupture scenarios can elucidate unexpected observations shortly after major earthquakes, providing timely insights for data-driven analysis and hazard assessment toward a comprehensive, physically consistent understanding of the mechanics of multi-fault systems.