A 3.7 earthquake shook up North County yesterday. According to the US Geological Survey, the epicenter was approximately 15 miles north of San Simeon. Things started to rattle at 6:38 in the morning. Residents as far south as Cambria felt the little quake. Frequent earthquake activity has been detected north of Paso Robles throughout the week. No damage has been reported as a result of the 3.7.