Crustal Shear‐Wave Velocity and Azimuthal Anisotropy Imaging Reveals the Merapi‐Merbabu‐Telomoyo Volcanic Chain, Central Java

Abstract We present new results from ambient noise tomography and azimuthal anisotropy analysis of the DOMERAPI data set to investigate crustal structure beneath the Merapi‐Merbabu‐Telomoyo region in central Java. The 3D shear‐wave velocity (Vs) model reveals a prominent high‐Vs anomaly extending from south of Merapi through Merbabu to Telomoyo, aligned with the Merapi‐Merbabu Fault. A low‐Vs anomaly to ∼8 km depth southwest of Merapi indicates a fluid‐rich or magmatically influenced upper crust. Azimuthal anisotropy exhibits dominant NNW‐SSE fast axis oreintations parallel to the volcanic chain but distinct from the direction of plate motion. Strong anisotropy beneath Merapi, contrasting with weaker anisotropy beneath high‐Vs Merbabu, highlights the role of local deformation and magmatism. Our results suggest upper‐crustal anisotropy is primarily governed by internally generated stresses within the overriding Sunda Plate, rather than by regional plate motion.