Rossi–Forel scale

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.

This system is still being used by some countries, including the Philippines.

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

• I. Microseismic shock. 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 shock. Recorded by several seismographs of different kinds. Felt by a small number of persons at rest.
• III. Very feeble shock. Felt by several persons at rest. Strong enough for the direction or duration to be appreciable.
• IV. Feeble shock. Felt by persons in motion. Disturbance of movable objects, doors, windows, cracking of ceilings.
• V. Shock of moderate intensity. Felt generally by everyone. Disturbance of furniture, ringing of some bells.
• VI. Fairly strong shock. 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. Strong shock. Overthrow of movable objects, fall of plaster, ringing of church bells. General panic. No damage to buildings.
• VIII. Very strong shock. Fall of chimneys, cracks in the walls of buildings.
• IX. Extremely strong shock. Partial or total destruction of some buildings.
• X. Shock of extreme intensity. Great disaster, ruins, disturbance of the strata, fissures in the ground, rock falls from mountains.

See also

• Richter Scale
• Other seismic scales

Bibliography

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