Rossi–Forel scale

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The Rossi–Forel scale was one of the first seismic scales to reflect earthquake intensities. Developed by Michele Stefano Conte de Rossi of Italy and François-Alphonse Forel of Switzerland in the late 19th century, it was used for about two decades until the introduction of the Mercalli intensity scale in 1902.

The Rossi–Forel scale and/or its modifications is still in use in some countries, such as the Philippines.


The 1873 version of the Rossi–Forel scale had 10 intensity levels:

  • I. Microseismic tremor. Recorded by a single seismograph or by seismographs of the same model, but not by several seismographs of different kinds. The shock felt by an experienced observer.
  • II. Extremely feeble tremor. Recorded by several seismographs of different kinds. Felt by a small number of persons at rest.
  • III. Feeble tremor. Felt by several persons at rest. Strong enough for the direction or duration to be appreciable.
  • IV. Slight tremor. Felt by persons in motion. Disturbance of movable objects, doors, windows, cracking of ceilings.
  • V. Moderate tremor. Felt generally by everyone. Disturbance of furniture, ringing of some bells.
  • VI. Strong tremor. General awakening of those asleep. General ringing of bells. Oscillation of chandeliers, stopping of clocks, visible agitation of trees and shrubs. Some startled persons leaving their dwellings.
  • VII. Very strong tremor. Overthrow of movable objects, fall of plaster, ringing of church bells. General panic. Moderate to heavy damage buildings.
  • VIII. Damaging tremor. Fall of chimneys. Cracks in the walls of buildings.
  • IX. Devastating tremor. Partial or total destruction of buildings.
  • X. Extremely high intensity tremor. Great disaster, ruins, disturbance of the strata, fissures in the ground, rock falls from mountains.

See also[edit]


  • Tiedemann, Herbert (1992). Earthquakes and Volcanic Eruptions. A Handbook on Risk Assessment. Zurich: Swiss Reinsurance Company.