High-Resolution Moho Depth and Vp/Vs Mapping beneath the
Carpatho-Pannonian Region Using P-Wave Coda Autocorrelation
Abstract
The Carpathian-Pannonian region (CPR), including Austria, Slovakia,
Hungary, Croatia, Serbia, Romania, and Ukraine, exhibits significant
seismic activity, necessitating detailed crustal studies. Despite recent
improvements in understanding CPR’s crustal structure, it remains poorly
known. Here, we applied improved autocorrelation of P-wave coda for the
first time in CPR to image the Moho and Vp/Vs ratio. We present Moho
depth estimates beneath 231 broadband seismic stations using
autocorrelation of teleseismic P-wave coda. Our results indicate a
shallow Moho beneath the Pannonian, Vienna, and Danube basins, with
depths between 20 and 30 km, while the deepest Moho is observed beneath
the Southern Carpathians, Apuseni Mountains, and Southeast Carpathians,
where it reaches depths of 45 to 55 km. The shallower Moho beneath the
basins indicates crustal thinning, while thicker Moho in neighboring
mountain belts indicates orogenic thickening. Additionally, we estimated
the crustal Vp/Vs ratio beneath 212 stations. The whole crust Vp/Vs
ratio varies from 1.6 to 2.1, with notably high ratios (1.9 to 2.1)
beneath the Pannonian, Vienna, and Danube basins. We also observed a
Vp/Vs ratio greater than 1.80 beneath a few stations where mid-crustal
low-velocity zones were detected. On average, the Vp/Vs ratio across the
region is 1.82, slightly higher than the global average for continental
crust. The lateral variations of Vp/Vs ratio indicate variation in
crustal composition across CPR. These findings contribute valuable
insights into the tectonics and crustal architecture of CPR.