The quake lasted several seconds and was felt across parts of the county, including in Yeovil, Taunton, Bridgwater and Cheddar, shortly before 11pm on Thursday.
Will Gater, an astronomer and journalist, described the sound he heard in Taunton as being like the noise ”inside an airplane” when “the engines start to throttle up for take-off”.
The sound was followed by “the walls shaking as if someone had violently slammed a heavy door”, he added in a tweet.
Another person in Taunton tweeted: ”My bedroom windows shook instantaneously and it felt like a big bird had hit it. Wondered what the hell it was.”
Others reported feeling their settees and beds shaking.
The British Geological Survey (BGS) said it had received several reports of the earthquake being felt in “several towns and villages in Somerset”.
Somerset also shook in February last year, in what the BGS described as “the biggest event in the area since the 5.2 magnitude earthquake in 1906”.