diff --git a/src/aashto/src/main/java/gov/usgs/earthquake/nshmp/netcdf/reader/ReaderGroundMotions.java b/src/aashto/src/main/java/gov/usgs/earthquake/nshmp/netcdf/reader/ReaderGroundMotions.java
index f45da139d717469be4fc52160892913a4d392736..716c3da4686aeb78d8a1f55318ce40484b599ebb 100644
--- a/src/aashto/src/main/java/gov/usgs/earthquake/nshmp/netcdf/reader/ReaderGroundMotions.java
+++ b/src/aashto/src/main/java/gov/usgs/earthquake/nshmp/netcdf/reader/ReaderGroundMotions.java
@@ -2,6 +2,8 @@ package gov.usgs.earthquake.nshmp.netcdf.reader;
 
 import java.io.IOException;
 
+import gov.usgs.earthquake.nshmp.netcdf.data.NetcdfData;
+import gov.usgs.earthquake.nshmp.netcdf.data.NetcdfDataGroundMotions;
 import gov.usgs.earthquake.nshmp.netcdf.data.NetcdfShape;
 import gov.usgs.earthquake.nshmp.netcdf.data.NetcdfShape.IndexKey;
 import gov.usgs.earthquake.nshmp.netcdf.reader.NetcdfUtils.Key;
@@ -29,4 +31,10 @@ public class ReaderGroundMotions extends Reader {
         .add(IndexKey.SITE_CLASS, vData.findDimensionIndex(Key.SITE_CLASS))
         .build();
   }
+
+  @Override
+  NetcdfDataGroundMotions readData(Group targetGroup) throws IOException {
+    NetcdfData netcdfData = super.readData(targetGroup);
+    return new NetcdfDataGroundMotions(netcdfData);
+  }
 }