diff --git a/src/main/java/gov/usgs/earthquake/nshmp/gmm/BooreAtkinson_2008.java b/src/main/java/gov/usgs/earthquake/nshmp/gmm/BooreAtkinson_2008.java
index eafbd2bb5fdab24836346d89bfb329675bbd58dd..e1961399edc103672b4864877e484b6559d5a217 100644
--- a/src/main/java/gov/usgs/earthquake/nshmp/gmm/BooreAtkinson_2008.java
+++ b/src/main/java/gov/usgs/earthquake/nshmp/gmm/BooreAtkinson_2008.java
@@ -163,12 +163,12 @@ public class BooreAtkinson_2008 implements GroundMotionModel {
    * Package visible site amplification model. This model is appropriate for use
    * with other GMMs where the reference rock site condition has Vs30=760.
    */
-  double siteAmp(double lnPga, double vs30) {
-    return calcSite(coeffs, lnPga, vs30);
+  double siteAmp(double pgaRef, double vs30) {
+    return calcSite(coeffs, pgaRef, vs30);
   }
 
   /* Site term */
-  private static double calcSite(Coefficients c, double lnPga, double vs30) {
+  private static double calcSite(Coefficients c, double pgaRef, double vs30) {
 
     double Flin = c.b_lin * log(vs30 / Vref);
 
@@ -184,17 +184,17 @@ public class BooreAtkinson_2008 implements GroundMotionModel {
     }
 
     double Fnl = 0.0;
-    if (lnPga <= A1) {
+    if (pgaRef <= A1) {
       Fnl = bnl * log(PGAlo / 0.1);
-    } else if (lnPga <= A2) {
+    } else if (pgaRef <= A2) {
       double dX = log(A2 / A1);
       double dY = bnl * log(A2 / PGAlo);
       double _c = (3.0 * dY - bnl * dX) / (dX * dX);
       double d = -(2.0 * dY - bnl * dX) / (dX * dX * dX);
-      double p = log(lnPga / A1);
+      double p = log(pgaRef / A1);
       Fnl = bnl * log(PGAlo / 0.1) + (_c * p * p) + (d * p * p * p);
     } else {
-      Fnl = bnl * log(lnPga / 0.1);
+      Fnl = bnl * log(pgaRef / 0.1);
     }
 
     return Flin + Fnl;