MassGIS Data: NEHRP Soil Classifications

May 2023

The purpose of this data collection effort is to improve the estimates of earthquake risk and potential losses determined in HAZUS-MH by reducing the uncertainty associated with classification of soils into the NEHRP (National Earthquake Hazard Reduction Program) categories (A, B, C, D and E) in Massachusetts.

Downloads

Download this data (197 MB) 

.zip file contains one shapefile and three PDF maps as described below, plus an ArcGIS layer file (.lyr).

ArcGIS Online map service  ArcGIS Online feature service 

Overview

This data layer consists of an updated National Earthquake Hazards Reduction Program (NEHRP) soil classification map of Massachusetts at 100-meter resolution. This is a statewide coverage that classifies soils according to the NEHRP soil categories A, B, C, D, and E. The category into which a soil is classified is determined by the average shear wave velocity in the top 30 meters (100 feet) of the earth’s surface. The classification is also dependent on the thickness of the soil cover that lies over the bedrock. This updated NEHRP soil classification map incorporates overburden thickness into the soil category determination that was previously unavailable.

The data layer includes one feature class named NEHRP_SITECLASS_POLY:

• NEHRP Soil Classifications for Massachusetts – This polygon feature class stores the NEHRP site classes for Massachusetts. It was created from a 100-meter resolution raster of the NEHRP site classes. The original raster and shapefile were created in geographic coordinates and subsequently converted to the Mass State Plane coordinate system.

Accompanying the data layer is a series of three regional maps in PDF format. The maps sheets are 36 in x 48 in; map scale is 1:125,000:

• NEHRP Soil Classification Map of Massachusetts: Sheet 1 – Western Massachusetts
• NEHRP Soil Classification Map of Massachusetts: Sheet 2 – Northeastern Massachusetts
• NEHRP Soil Classification Map of Massachusetts: Sheet 3 – Southeastern Massachusetts

Production

Multiple agencies and individuals contributed to these data products. The work was done in cooperation with the Massachusetts Geological Survey, GISmatters, Inc., and Tufts University Department of Civil and Environmental Engineering. This work was funded by the Massachusetts Department of Transportation (Award Number INTF00X02021A0113776) and the Massachusetts Emergency Management Agency (Award Number ISACDAHM437905UM821A).

The NEHRP soil categories were determined using the statewide Surficial Materials Map – A 1:24,000-Scale Geologic Map Database (Stone and others, 2019), the statewide 100-meter resolution depth to bedrock map (Mabee and others, 2023) and shear wave velocity profiles collected from various sources. See the Final Report for a summary documenting the source data and methods used to create the NEHRP site class maps.

Suggested citation:

Mabee, S.B., M.A. Pontrelli, C.C. Duncan, W.P. Clement, 2023, Updated NEHRP soil classification map of Massachusetts. Massachusetts Geological Survey Miscellaneous Map 23-01. 3 maps, 1:125,000 scale, ESRI GIS shapefile, metadata, 106-page report.

Related Data

Also see the Bedrock Altitude and Overburden Thickness Layers.

Attributes

The layer's polygon attribute table contains one added field:

TYPE	NEHRP Site Classification Category (A, B, C, D, E) Category Description Mean Shear Wave Velocity to 30 m Depth A Hard Rock >1500 m/s B Firm to Hard Rock 760-1500 m/s C Dense Soil, Soft Rock 360-760 m/s D Stiff Soil 180-360 m/s E Soft Clays <180 m/s

Maintenance

The Tufts University Department of Civil and Environmental Engineering and Massachusetts Geological Survey (MGS) maintain the data. The NEHRP site class maps are static products that do not require active maintenance or updates. Over the long term, these maps may need to be depreciated and/or swapped out with new maps if a new depth to bedrock raster or shear wave velocity profile data become available from either MGS or Tufts University.