diff --git a/src/main/java/gov/usgs/earthquake/nshmp/gmm/GroundMotions.java b/src/main/java/gov/usgs/earthquake/nshmp/gmm/GroundMotions.java
index c7534107f71b85b2728c7f1a2de9ed48b99bc1e9..d6194a84e0dd7da4866927ea0b53e6a814a6a18d 100644
--- a/src/main/java/gov/usgs/earthquake/nshmp/gmm/GroundMotions.java
+++ b/src/main/java/gov/usgs/earthquake/nshmp/gmm/GroundMotions.java
@@ -165,6 +165,11 @@ public class GroundMotions {
       return 1;
     }
 
+    @Override
+    public String toString() {
+      return LogicTree.toString(this);
+    }
+
     @Override
     public Branch<GroundMotion> get(int index) {
       return new Branch<GroundMotion>() {
@@ -183,6 +188,11 @@ public class GroundMotions {
         public double weight() {
           return 1.0;
         }
+
+        @Override
+        public String toString() {
+          return Branch.toString(this);
+        }
       };
     }
   }
@@ -218,6 +228,16 @@ public class GroundMotions {
       throw new UnsupportedOperationException();
     }
 
+    @Override
+    public int size() {
+      return μs.length;
+    }
+
+    @Override
+    public String toString() {
+      return LogicTree.toString(this);
+    }
+
     @Override
     public Branch<GroundMotion> get(int index) {
       return new Branch<GroundMotion>() {
@@ -235,12 +255,12 @@ public class GroundMotions {
         public double weight() {
           return wts[index];
         }
-      };
-    }
 
-    @Override
-    public int size() {
-      return μs.length;
+        @Override
+        public String toString() {
+          return Branch.toString(this);
+        }
+      };
     }
   }
 
@@ -288,6 +308,11 @@ public class GroundMotions {
       return μs.length * σs.length;
     }
 
+    @Override
+    public String toString() {
+      return LogicTree.toString(this);
+    }
+
     @Override
     public Branch<GroundMotion> get(int index) {
       return new Branch<GroundMotion>() {
@@ -314,6 +339,11 @@ public class GroundMotions {
         public double weight() {
           return μWts[μIndex] * σWts[σIndex];
         }
+
+        @Override
+        public String toString() {
+          return Branch.toString(this);
+        }
       };
     }
   }