The earthquakes hit just days after last year’s near-catastrophe at Oroville Dam, when the spillway cracked amid heavy rains and 188,000 people fled in fear of flooding. The timing of the two small tremors about 75 miles north of Sacramento was curious, and frightening. Were the quakes part of a seismic hot spot that caused the giant concrete spillway to tear? Was the weight of the water behind the dam triggering the quakes? Could all of Lake Oroville be prone to slipping?