Merge branch 'kbcg-sigma-casc-241' into 'main'

KBCG_20 sigma update for Cascadia

See merge request !406

src/main/java/gov/usgs/earthquake/nshmp/gmm/KuehnEtAl_2020.java

@@ -20,7 +20,6 @@ import java.util.Map;
 
 import com.google.common.collect.Range;
 
-import gov.usgs.earthquake.nshmp.Maths;
 import gov.usgs.earthquake.nshmp.gmm.GmmInput.Constraints;
 import gov.usgs.earthquake.nshmp.gmm.GroundMotionTables.GroundMotionTable;
 import gov.usgs.earthquake.nshmp.gmm.GroundMotionTables.GroundMotionTable.Position;
@@ -329,11 +328,10 @@ public abstract class KuehnEtAl_2020 implements GroundMotionModel {
       μ = max(μ, μPga);
     }
 
-    // applying tiger team sigma fix to everything except
-    // Cascadia until conus changes are approved
-    double σ = coeffs.zone != CASCADIA
-        ? calcStdDev(coeffs, coeffsPGA, in.vs30, pgaRef)
-        : Maths.hypot(coeffs.φ, coeffs.τ);
+    // Tiger team recommendation to use CB14 sigma that
+    // accounts for non-linear amplification
+    double σ = calcStdDev(coeffs, coeffsPGA, in.vs30, pgaRef);
+
     Position p = epistemicTable.position(in.rRup, in.Mw);
     double ψ = epistemicTable.get(p);