Hi Petra and Lowell. The 3.1 Aptos quake occurred near the very end of the Zayante-Vergeles fault. This fault starts at 36.79/-121.46 and ends at 37.09/-121.94. The creep rate is 0.10mm per year

It is quite capable of having a quake up to 6.8Ml. Over a couple of years now there has been quite a bit of activity in the area of San Juan Bautista that could be associated with this fault.

There isn’t a very good recorded history regarding this fault. Take Care…Don in creepy town