  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.
