Comparisons of triggered tremor in California

We conduct a visual inspection of deep nonvolcanic tremor triggered by large teleseismic earthquakes around the Calaveras fault in northern California (NC) and the San Jacinto fault in southern California (SC). Out of the 42 large (M _w ≥ 7:5) earthquakes between 2001 and 2010, only the 2002 M _w 7.9 Denali fault earthquake triggered clear tremor in these two regions. This is in marked contrast with the Parkfield-Cholame section of the San Andreas fault in central California (CC), where 12 earthquakes have triggered tremor in that region. The amplitude of the triggered tremor correlates with that of the triggering surface waves in CC and is consistent with the clock-advance model. The lack of widespread triggered tremor in NC and SC is not simply a consequence of their different background noise levels from CC, but rather reflects different background tremor rates in these regions. Online Material: Tables of parameters for triggered/nontriggered teleseismic earthquakes and triggered tremors, and figures of band-pass-filtered seismograms, maximum vertical PGVs versus median amplitude of band-pass-filtered envelope functions, tremor amplitude versus PGV, and S-wave spectra (and corresponding noise) of local selected earthquakes.