Seismoscope, Earthquake House Comrie

Image: © Jim Barton Taken: 7 Oct 2010

This is a reconstruction of the early instrument for monitoring earthquake tremors installed in this purpose-built shelter in 1874. The wooden cross lies on a bed of sand to isolate it from nearby disturbance. On each arm are placed three wooden cylinders of the same height but different diameters. A tremor would cause one or more cylinders to topple, with only a strong tremor affecting the thickest cylinders. Hence the number and direction of cylinders knocked down and recorded in the sand would indicate strength and direction of a tremor. In fact, the earthquake activity of the 1840's did not recur, and the instrument never functioned. The building was restored from 1986 by Perth and Kinross Council with Perth and Kinross Heritage Trust and British Geological Survey. BGS maintain a modern seismometer, here visible as the metal cylinder at the top corner of the sand tray. The green colouration is due to reflection in the glass window through which the photograph was taken.

Images are licensed for reuse under creativecommons.org/licenses/by-sa/2.0