Add pgv label

src/hazard/src/main/java/gov/usgs/earthquake/nshmp/netcdf/www/NetcdfServiceHazardCurves.java

@@ -36,6 +36,7 @@ public class NetcdfServiceHazardCurves extends
 
   static final String SERVICE_DESCRIPTION = "Get static hazard curves from a NetCDF file";
   static final String X_LABEL = "Ground Motion (g)";
+  static final String X_LABEL_PGV = "Ground Motion (cm/s)";
   static final String Y_LABEL = "Annual Frequency of Exceedence";
 
   public NetcdfServiceHazardCurves(NetcdfDataFilesHazardCurves netcdfDataFiles) {
@@ -211,8 +212,9 @@ public class NetcdfServiceHazardCurves extends
       RequestDataSiteClass request,
       Imt imt,
       XySequence curves) {
+    var xLabel = imt == Imt.PGV ? X_LABEL_PGV : X_LABEL;
     var metadata =
-        new HazardResponseMetadata(request.siteClass, imt, X_LABEL, Y_LABEL);
+        new HazardResponseMetadata(request.siteClass, imt, xLabel, Y_LABEL);
     return new ResponseData<>(metadata, curves);
   }