Wondering if Anza is on the verge of a larger quake? It's possible, but unlikely, according to seismologist Debi Kilb. Based on Bath’s law, the expected largest aftershock is 1.2 magnitude (Mw) units smaller than the mainshock. In the Anza region the largest aftershocks tend to be smaller than expected. Of the six Anza EQs over Mw 4.5, only the 2013 sequence behaved as expected. The largest aftershock to date of Friday’s Anza Mw 4.9 EQ is Mw 3.5, falling below the expect 3.7 (4.9-1.2) value. This plot indicates that regardless of the mainshock magnitude, the largest aftershocks all tend to be approximately Mw 3.5.