Measures the rate of change in motion of the earth's surface and expresses it as a percent of the established rate of acceleration due to gravity (9.8 m/sec2)
New York City Government, New York City Natural Hazard Mitigation Plan, Appendix B: Glossary, New York, USA 2009. http://www.nyc.gov/html/oem/downloads/pdf/hazard_m itigation/appendix_b_glossary.pdf, (ND/ Gen - Amer) {894}