Application of IRIS/IDA Stations in the USSR to Seismic Monitoring Research: TheUse of Velocity Spectrum in the Stacking of Receiver Functions with Application to IRIS Station at Obninsk, USSR

摘要

In order to improve the signal-to-noise ratio of receiver function data, it istypical to stack receiver functions calculated from events at similar distances and back azimuths. We have adapted the velocity spectrum stacking technique, used extensively in reflection seismology, to the receiver function method in order to stack data with different ray parameters, thereby improving further the signal-to-noise ratio. Perhaps more importantly, by producing the velocity spectrum stacks we take advantage of the differences in the shapes of the moveout curves of converted phases and reverberations to identify and separate the various phases and to infer velocity structure. Through conventional receiver function techniques we have modeled the crustal structure beneath the IRIS/IDA seismographic station at Obninsk, Russia. This model includes a low-velocity, 2 km thick surface layer, and a 47 km depth to Moho with relatively uncomplicated crustal structure. By comparison of the velocity spectrum stacks produced from the observed data at Obninsk with those produced from PREM synthetics we have identified Ps phases from the 410 and 670 km discontinuities. We find no evidence of a 210 km discontinuity beneath Obninsk in the receiver function data.