“…For instance PREM predicts slowness magnitudes of 2.7 s/deg for PcP and 0.71 s/deg for PKiKP , and the expected backazimuth is 145°. Slowness anomalies at arrays are not uncommon and can arise because of deep earth velocity heterogeneities [ Kanasewich et al , 1972; Tibuleac and Herrin , 1999], near receiver site effects [ Lin and Roecker , 1996; Tibuleac and Herrin , 1997], or intra‐array velocity variations, including topography [ Bokelmann , 1995]. Accounting for such anomalies is critical when slownesses are used in event location, and a large amount of effort has gone into calibrating various array stations and generating corrective slowness perturbations [ Koch and Kradolfer , 1997; Bondar and North , 1999; Bondar et al , 1999].…”