Seven independent lines of evidence can be cited for the existence of a shallow-crustal anomalous zone at a site near the south end of Hilton Creek fault, near Mammoth Lakes, California. They are: (1) the presence of a persistent seismic gap since detailed observations began in 1979; (2) S-wave shadowing for travel paths crossing the site; (3) a low-velocity anomaly associated with the south end of Hilton Creek fault discovered by seismic tomography; (4) the observation of two non-double-couple mechanisms for large earthquakes a few km east and west of the site; (5) a concentration of pre-S-arrivals indicative of a possible reflection in the vicinity of this site; (6) a geometric symmetry of source-receiver paths showing pre-S arrivals about this site; and (7) [new evidence presented herein] travel-time fits of strong pre-S arrivals recorded at epicenter of the 1978 Wheeler Crest event (ML 5.7).

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