|rȯ]sēfəˈrel-, |rä] noun
Usage: usually capitalized R&F
Etymology: after Michele Stefano De Rossi died 1898 Italian geologist and François Alphonse Forel died 1912 Swiss naturalist
: an arbitrary numerical scale of intensity of seismic disturbances ranging from one for a barely perceptible tremor to 10 for an earthquake of the highest intensity