Upper Mantle Shear Velocity Model

CUB shear velocity model is created from a large data set of the surface wave fundamental model phase and group velocity measurements. Phase velocities in period range between 40 an 150 s are generously donated by Harvard University and Utrecht University. These phase velocity data sets are described by Ekström et al. (1997) and Trampert and Woodhouse (1995). The group velocity measurements at periods between 16 and 200s are performed at the Center for Imaging the Earth's Interior in the University of Colorado at Boulder. The group velocities are measured with the frequency-time analysis (Levshin et al., 1989) in which for every waveform a human analyst defines the frequency range of measurements and separate the signal form a variety of noise sources (e.g., overtones, fundamental modes of different types, other earthquakes, multipaths, scattered arrivals). We used broadband waveforms following earthquakes occurred from 1997 to present and recorded at stations from both global networks (GDSN, GSN, GEOSCOPE) as well as temporary regional arrays. At present, the group velocity dataset is composed of about 200000 paths.

Data coverage is generally better for Rayleigh waves than for Love waves, is better at intermediate periods than at very short or very long periods, and is better in the northern than in the southern hemisphere. This heterogeneous data coverage is imposed by the distribution of seismic stations and earthquakes. Data coverage optimizes in Eurasia and is currently worst across Africa, the central Pacific, parts of the Indian Ocean, and Antarctica.