A notch structure on the Moho beneath the Eastern San Gabriel Mountains

Synthetic waveform modeling of the anomalous receiver functions for two stations in the eastern San Gabriel Mountains, California, suggests that a flat-topped notch structure exists on the Moho. North of the San Andreas Fault (SAF), the Moho depth is 36–38 km and is 33–35 km south of the San Gabriel Fault (SGF), but in-between under the Mt. Baldy block, it is only ∼ 29 km. The inferred notch structure is also supported by the Pms arrival times along the SCSN and the LARSE I profiles. The shallow Moho block correlates well with the surficial exposure of the lower plate Pelona Schist or where it resides at very shallow depth. The large Moho offsets across the two major faults can be either related to differential uplifting reflected by the difference in the denudation rate and the exposure of the lower plate Pelona Schist, or it can be the result of the juxtaposition of the distinctive terranes with initially different Moho depth due to the strike-slip movements along the two major faults.