The Pendleton Fault, sometimes called the Irwell Valley Fault, stretches for about 20 miles (32 km) from Bolton in Greater Manchester in the north along the Irwell Valley through Pendleton and south to Poynton in Cheshire, running northwest–southeast. The fault throws the beds of the Middle Coal Measures of the Manchester CoalfieldThe Manchester Coalfield is part of the Lancashire Coalfield. Some easily accessible seams were worked on a small scale from the Middle Ages, and extensively from the beginning of the Industrial Revolution until the last quarter of the 20th century. by 1,000 feet (300 m) on its western side. The fault is active, and movement has caused earthquakes. An earthquake of intensity 6 on the Richter scale that occurred on 10 February 1889 was felt over an area of 2,500 square miles (6,500 km2). Lesser shocks were recorded in 1931 and 1944. Coal mining in the Irwell Valley between Bolton and Pendleton may account for small movements, although most collieries in the area had closed by 1929.
In 2007 a swarm of six earthquakes felt across the region was attributed to the fault.