A series of small earthquakes rattled Northern California early Thursday, with the U.S. Geological Survey reporting at least five events in rapid succession in the Geysers geothermal field north-east of Healdsburg. The strongest temblor, a magnitude-4.0, struck at 5:40 a.m. Pacific time, about 13 miles from Healdsburg in Sonoma County. Three more quakes followed within minutes, and a fifth was recorded at 7:05 a.m. Shaking was felt across Sonoma, Lake and Mendocino counties, with one report from San Mateo roughly 85 miles away. Local officials said there were no immediate reports of injuries, structural damage or service interruptions. The Geysers is one of California’s most seismically active zones because of its extensive geothermal energy operations. USGS seismologists said such clusters are common and typically do not portend a larger event, though they can temporarily raise the likelihood of additional small quakes in the area over the next few days.