Array analysis of ScP : D'' velocity anomalies and the tilt of CMB

Analysis of the ScP phase, reflected seismic phase from the core-mantle boundary, using short-period data form some seismic arrays. We surveyed the CI array (Caltech Regional Seismic Network), UW array (Pacific North Regional Seismic Network) in Northern America region and KN array (Kyrgyz Seismic Telemetry Network), XW array (Tien Shan Continental Dynamics network), XR array (INDEPTH III ) in Tibet region, XI array (NE China Seismic Experiment ), J-array , CWBSN (Central Weather Bureau Seismic network of Taiwan ) in East Asia region. We analyzed the teleseismic events with depth >100 km that are recorded clear ScP phase by using array technique. Most interesting is that the ScP slowness observed for some events which ScP converted points in Borneo in southwestern Pacific region. The slowness of ScP systematically differs with PREM predicted. We also noticed that there is a gap between positive and negative anomalies of ScP slowness. Negative slowness anomaly means steeper path than in PREM. Positive slowness anomaly means shallower path than in PREM. In other regions, the slowness of ScP are similar with PREM predicted. After some synthetic test, the slowness anomalies probably derived from a locally tilted interface at the CMB or the variation of P wave velocity in D''. It still can't explain all slowness anomalies. Some unknowed factors those stand prominent on the slowness anomalies.