diff --git a/src/main/java/gov/usgs/earthquake/nshmp/calc/CalcConfig.java b/src/main/java/gov/usgs/earthquake/nshmp/calc/CalcConfig.java
index 356e8933f46822c18e2f813e7942dd3b1658abd3..4e9d75d7458d2a262e43058623d3fab8e3c55bbc 100644
--- a/src/main/java/gov/usgs/earthquake/nshmp/calc/CalcConfig.java
+++ b/src/main/java/gov/usgs/earthquake/nshmp/calc/CalcConfig.java
@@ -1073,15 +1073,6 @@ public final class CalcConfig {
      */
     public final boolean smoothGrids;
 
-    /**
-     * Whether to collapse/combine magnitude-frequency distributions, or not.
-     * Doing so prevents uncertainty analysis as logic-tree branches are
-     * obscured.
-     *
-     * <p><b>Default:</b> {@code true}
-     */
-    public final boolean collapseMfds;
-
     /**
      * The partition or batch size to use when distributing
      * {@link SourceType#FAULT_SYSTEM} calculations.
@@ -1100,13 +1091,11 @@ public final class CalcConfig {
     private Performance(
         boolean optimizeGrids,
         boolean smoothGrids,
-        boolean collapseMfds,
         int systemPartition,
         ThreadCount threadCount) {
 
       this.optimizeGrids = optimizeGrids;
       this.smoothGrids = smoothGrids;
-      this.collapseMfds = collapseMfds;
       this.systemPartition = systemPartition;
       this.threadCount = threadCount;
     }
@@ -1116,7 +1105,6 @@ public final class CalcConfig {
           .append(LOG_INDENT).append("Performance")
           .append(formatEntry(Key.OPTIMIZE_GRIDS, optimizeGrids))
           .append(formatEntry(Key.SMOOTH_GRIDS, smoothGrids))
-          .append(formatEntry(Key.COLLAPSE_MFDS, collapseMfds))
           .append(formatEntry(Key.SYSTEM_PARTITION, systemPartition))
           .append(formatEntry(Key.THREAD_COUNT, threadCount.name()));
     }
@@ -1125,7 +1113,6 @@ public final class CalcConfig {
 
       Boolean optimizeGrids;
       Boolean smoothGrids;
-      Boolean collapseMfds;
       Integer systemPartition;
       ThreadCount threadCount;
 
@@ -1133,7 +1120,6 @@ public final class CalcConfig {
         return new Performance(
             optimizeGrids,
             smoothGrids,
-            collapseMfds,
             systemPartition,
             threadCount);
       }
@@ -1141,7 +1127,6 @@ public final class CalcConfig {
       void copy(Performance that) {
         this.optimizeGrids = that.optimizeGrids;
         this.smoothGrids = that.smoothGrids;
-        this.collapseMfds = that.collapseMfds;
         this.systemPartition = that.systemPartition;
         this.threadCount = that.threadCount;
       }
@@ -1153,9 +1138,6 @@ public final class CalcConfig {
         if (that.smoothGrids != null) {
           this.smoothGrids = that.smoothGrids;
         }
-        if (that.collapseMfds != null) {
-          this.collapseMfds = that.collapseMfds;
-        }
         if (that.systemPartition != null) {
           this.systemPartition = that.systemPartition;
         }
@@ -1168,7 +1150,6 @@ public final class CalcConfig {
         Builder b = new Builder();
         b.optimizeGrids = true;
         b.smoothGrids = true;
-        b.collapseMfds = true;
         b.systemPartition = 1000;
         b.threadCount = ThreadCount.ALL;
         return b;
@@ -1177,7 +1158,6 @@ public final class CalcConfig {
       void validate() {
         checkNotNull(optimizeGrids, STATE_ERROR, Performance.ID, Key.OPTIMIZE_GRIDS);
         checkNotNull(smoothGrids, STATE_ERROR, Performance.ID, Key.SMOOTH_GRIDS);
-        checkNotNull(collapseMfds, STATE_ERROR, Performance.ID, Key.COLLAPSE_MFDS);
         checkNotNull(systemPartition, STATE_ERROR, Performance.ID, Key.SYSTEM_PARTITION);
         checkNotNull(threadCount, STATE_ERROR, Performance.ID, Key.THREAD_COUNT);
       }
@@ -1206,7 +1186,6 @@ public final class CalcConfig {
     /* performance */
     OPTIMIZE_GRIDS,
     SMOOTH_GRIDS,
-    COLLAPSE_MFDS,
     SYSTEM_PARTITION,
     THREAD_COUNT,
     QUEUE_SIZE,