A magnitude 3.9 earthquake occurred early on Wednesday morning, October 28th, 2026, at 5:01 am local time near Ukiah, Mendocino County, California, USA, as reported by the United States Geological Survey.According to preliminary data, the quake was located at a shallow depth of 6.6 miles. Shallow earthquakes are felt more strongly than deeper ones because they are closer to the surface. The exact magnitude, epicenter, and depth of the quake might be revised within the next few hours or minutes as seismologists review the data and refine their calculations, or as other agencies issue their reports.A second report was later issued by the European-Mediterranean Seismological Centre (EMSC), which also listed it as a magnitude 3.9 earthquake.Based on the preliminary seismic data, the quake should not have caused any significant damage but was probably felt by many people as light vibration in the area of the epicenter. Weak shaking might have been felt in Potter Valley (pop. 650), located 15 miles from the epicenter; Redwood Valley (pop. 1,700), 21 miles away; Willits (pop. 4,900), 22 miles away; Brooktrails (pop. 3,200), 23 miles away; Nice (pop. 2,700), 27 miles away; Ukiah (pop. 15,900), 28 miles away; and North Lakeport (pop. 3,300), 29 miles away.Other towns or cities near the epicenter where the quake might have been felt as very weak shaking include Clearlake (pop. 15,200), located 41 miles from the epicenter.Earthquake data: Date & time: Oct 28, 2026 12:01 pm (Universal Time) local time (28 Oct 2026 12:01 GMT)Magnitude: 3.9Hypocenter depth: 10.59 kmEpicenter coordinates: 39.5°N / 122.95°W (Lake County, California, United States)Primary data source: USGS