Data Key

Earthquake hazard

Spectral Acceleration; % Gravity

earthquake map of NY; click to enlarge
This map reflects soil amplification factors and resulting adjustment to the baseline USGS seismic map based on NYS Geological Survey classification of surfical geologic materials to National Earthquake Hazard Reduction Program (NEHRP) soil site classifications (A-E) and their associated amplification coefficients as referenced in 2003 NEHRP Recommended Provisions for New Building and Other Structures -- Part: Provisions (FEMA 450)
  <25%
  25%-35%
  35%-45%
  45%-55%
  55%-65%
  65%-75%
  75%-94%

Flood zones

  • Zone A: An area inundated by 100-year flooding, for which no Base Flood Elevations have been established.
  • Zone AE: An area inundated by 100-year flooding, for which Base Flood Elevations have been determined.
  • Zone AH: An area inundated by 100-year flooding (usually an area of ponding), for which Base Flood Elevations have been determined; flood depths range from 1 to 3 feet.
  • Zone AO: An area inundated by 100-year flooding (usually sheet flow on sloping terrain), for which average depths have been determined; flood depths range from 1 to 3 feet.
  • Zone X500: An area inundated by 500-year flooding; an area inundated by 100-year flooding with average depths of less than 1 foot or with drainage areas less than 1 square mile; or an area protected by levees from 100-year flooding.
  • Zone X: An area that is determined to be outside the 100- and 500-year floodplains.
  • nd = no data available
flood hazard map of NY; click to enlarge

Hurricane storm surge hazard

Inundation surge zones are worst case flooding based on surge height calculations from NOAA Sea, Lake and Overland Surge From Hurricanes -- SLOSH Model.

What do the different storm surge zones mean? (from NOAA)

hurricane storm surge hazard map of NYC and Long Island area of NY; click to enlarge

(Maps and data above from New York State Emergency Management Office external link; opens in a new window)

Last Updated: September 22, 2009 -- asm