V.—The Pendleton Earth-shake of November 25th, 1905

Extract

Pendleton lies on the north-west side of Manchester and within the borough of Salford, and is traversed by the well-known Pendleton or Irwell Valley fault, a fault which has been traced for more than twenty miles from the neighbourhood of Bolton to that of Poynton in Cheshire. The fault is still slowly growing, for, on February 10th, 1889, a slip near Bolton gave rise to an earthquake of intensity 6, felt over an area of about 2,500 square miles. Small superficial movements may also be taking place close to Pendleton, though here probably aided by mining operations. Within the last seven years there have been local shakes on three occasions, namely, February 27th, 1899, April 7th, 1900, and November 25th, 1905. The materials for the study of the first two of these shakes are not quite sufficient to determine the boundaries of their disturbed areas with accuracy. The areas appear, however, to have been approximately circular in form and about four or five miles in diameter. In both cases the intensity of the shock was 4, or nearly 5. In 1899 the centre of the disturbed area was about half a mile north of Pendleton and a short distance on the north-east or downthrow side of the Pendleton fault; in 1900 it lay a mile or two farther to the south or south-south-east of the former centre.