Merge pull request #428 from pmpowers-usgs/sub-basin-term-update

Sub basin term update

Author: pmpowers-usgs

src/gov/usgs/earthquake/nshmp/gmm/AtkinsonMacias_2009.java

@@ -114,7 +114,7 @@ private static final class Coefficients {
   private final Coefficients coeffs;
   private final Coefficients coeffsPGA;
   private final BooreAtkinson_2008 siteAmp;
-  private final CampbellBozorgnia_2014.BasinAmp cb14basinAmp;
+  private final CampbellBozorgnia_2014 cb14;
 
   // interpolatedGmm = null if !interpolated
   private final boolean interpolated;
@@ -128,7 +128,7 @@ private static final class Coefficients {
     coeffs = new Coefficients(imt, COEFFS);
     coeffsPGA = new Coefficients(PGA, COEFFS);
     siteAmp = new BooreAtkinson_2008(imt);
-    cb14basinAmp = new CampbellBozorgnia_2014.BasinAmp(imt);
+    cb14 = new CampbellBozorgnia_2014(imt);
     interpolated = INTERPOLATED_IMTS.containsKey(imt);
     interpolatedGmm = interpolated
         ? new InterpolatedGmm(subtype, imt, INTERPOLATED_IMTS.get(imt))
@@ -147,21 +147,20 @@ public final ScalarGroundMotion calc(final GmmInput in) {
     double site = siteAmp.siteAmp(μPga, in.vs30);
     double μAm = μRef + site;
 
-    if (!Double.isNaN(in.z2p5) && basinEffect()) {
-
-      double cbSite = cb14basinAmp.basinDelta(in, VS30_REF);
-      double μCb = μRef + cbSite;
-
-      /* Short-circuit lower values and short periods. */
-      int imtId = coeffs.imt.ordinal();
-      if ((μCb < μAm) || (imtId < Imt.SA0P75.ordinal())) {
-        return DefaultScalarGroundMotion.create(μAm, σ);
-      } else if (imtId < Imt.SA1P0.ordinal()) {
-        double μScaled = GmmUtils.scaleSubductionSiteAmp(coeffs.imt, μAm, μCb);
-        return DefaultScalarGroundMotion.create(μScaled, σ);
+    /*
+     * Add CB14 deep basin amplification term if (1) z2p5 is non-NaN, (2) this
+     * instance is basin amplifying and (3) T>0.5s
+     */
+    if (!Double.isNaN(in.z2p5) &&
+        basinEffect() &&
+        coeffs.imt.ordinal() > Imt.SA0P5.ordinal()) {
+      double cbBasinTerm = cb14.deepBasinAmplification(in.z2p5);
+      if (coeffs.imt == Imt.SA0P75) {
+        cbBasinTerm *= 0.585; // log T scaling at 0.75s
       }
-      return DefaultScalarGroundMotion.create(μCb, σ);
+      μAm += cbBasinTerm;
     }
+
     return DefaultScalarGroundMotion.create(μAm, σ);
   }
 

src/gov/usgs/earthquake/nshmp/gmm/BcHydro_2012.java

@@ -109,7 +109,6 @@ public abstract class BcHydro_2012 implements GroundMotionModel {
   private static final double SIGMA = 0.74;
   private static final double ΔC1_SLAB = -0.3;
   private static final double VS30_ROCK = 1000.0;
-  private static final double VS30_REF = 760.0; // refrence vs30 for CB basin Δ
 
   private static final Map<Imt, Range<Imt>> INTERPOLATED_IMTS = Maps.immutableEnumMap(
       ImmutableMap.of(SA0P03, Range.closed(SA0P02, SA0P05)));
@@ -141,7 +140,7 @@ private static final class Coefficients {
 
   private final Coefficients coeffs;
   private final Coefficients coeffsPGA;
-  private final CampbellBozorgnia_2014.BasinAmp cb14basinAmp;
+  private final CampbellBozorgnia_2014 cb14;
 
   // interpolatedGmm = null if !interpolated
   private final boolean interpolated;
@@ -150,7 +149,7 @@ private static final class Coefficients {
   BcHydro_2012(final Imt imt, Gmm subtype) {
     coeffs = new Coefficients(imt, COEFFS);
     coeffsPGA = new Coefficients(PGA, COEFFS);
-    cb14basinAmp = new CampbellBozorgnia_2014.BasinAmp(imt);
+    cb14 = new CampbellBozorgnia_2014(imt);
     interpolated = INTERPOLATED_IMTS.containsKey(imt);
     interpolatedGmm = interpolated
         ? new InterpolatedGmm(subtype, imt, INTERPOLATED_IMTS.get(imt))
@@ -166,22 +165,20 @@ public final ScalarGroundMotion calc(final GmmInput in) {
     double pgaRock = exp(calcMean(coeffsPGA, isSlab(), 0.0, in.Mw, in.rRup, in.zTop, VS30_ROCK));
     double μAsk = calcMean(coeffs, isSlab(), pgaRock, in.Mw, in.rRup, in.zTop, in.vs30);
 
-    if (!Double.isNaN(in.z2p5) && basinEffect()) {
-      
-      double μRef = calcMean(coeffs, isSlab(), pgaRock, in.Mw, in.rRup, in.zTop, VS30_REF);
-      double cbBasin = cb14basinAmp.basinDelta(in, VS30_REF);
-      double μCb = μRef + cbBasin;
-
-      /* Short-circuit lower values and short periods. */
-      int imtId = coeffs.imt.ordinal();
-      if ((μCb < μAsk) || (imtId < Imt.SA0P75.ordinal())) {
-        return DefaultScalarGroundMotion.create(μAsk, SIGMA);
-      } else if (imtId < Imt.SA1P0.ordinal()) {
-        double μScaled = GmmUtils.scaleSubductionSiteAmp(coeffs.imt, μAsk, μCb);
-        return DefaultScalarGroundMotion.create(μScaled, SIGMA);
+    /*
+     * Add CB14 deep basin amplification term if (1) z2p5 is non-NaN, (2) this
+     * instance is basin amplifying and (3) T>0.5s
+     */
+    if (!Double.isNaN(in.z2p5) &&
+        basinEffect() &&
+        coeffs.imt.ordinal() > Imt.SA0P5.ordinal()) {
+      double cbBasinTerm = cb14.deepBasinAmplification(in.z2p5);
+      if (coeffs.imt == Imt.SA0P75) {
+        cbBasinTerm *= 0.585;// log T scaling at 0.75s
       }
-      return DefaultScalarGroundMotion.create(μCb, SIGMA);
+      μAsk += cbBasinTerm;
     }
+
     return DefaultScalarGroundMotion.create(μAsk, SIGMA);
   }
 

src/gov/usgs/earthquake/nshmp/gmm/CampbellBozorgnia_2014.java

@@ -179,27 +179,11 @@ private static ScalarGroundMotion calc(
   }
 
   /*
-   * Convenience method for Campbell site/basin delta relative to a reference
-   * site condition, vs30ref, which may be different than Campbell's reference
-   * rock site condition of Vs30=1100 m/s.
+   * Return the CB14 basin amplification term for deep basins only, z2.5 > 3km
+   * and Fsed > 0.
    */
-  double basinDelta(GmmInput in, double vs30ref) {
-    FaultStyle style = GmmUtils.rakeToFaultStyle_NSHMP(in.rake);
-    boolean basinAmp = basinAmpOnly();
-
-    /* Rock reference value with default basin term. */
-    double pgaRock = (vs30ref < coeffs.k1)
-        ? exp(calcMean(coeffsPGA, style, 1100.0, 0.398, 0.0, in, basinAmp))
-        : 0.0;
-    double μRock = calcMean(coeffs, style, vs30ref, Double.NaN, pgaRock, in, basinAmp);
-
-    /* Now with site/basin effect. */
-    pgaRock = (in.vs30 < coeffs.k1)
-        ? exp(calcMean(coeffsPGA, style, 1100.0, 0.398, 0.0, in, basinAmp))
-        : 0.0;
-    double μBasin = calcMean(coeffs, style, in.vs30, in.z2p5, pgaRock, in, basinAmp);
-
-    return μBasin - μRock;
+  double deepBasinAmplification(double z2p5) {
+    return Math.max(calcBasinTerm(coeffs, z2p5), 0.0);
   }
 
   // Mean ground motion model -- we use supplied vs30 and z2p5 rather than

src/gov/usgs/earthquake/nshmp/gmm/GmmUtils.java

@@ -309,42 +309,4 @@ static double atkinsonTableValue(final GroundMotionTable table, final Imt imt,
     }
     return μ;
   }
-
-  /* */
-  static double scaleSubductionSiteAmp(Imt imt, double lo, double hi) {
-    double scale = subductionBasinPeriodScale(imt);
-    return lo + (hi - lo) * scale;
-  }
-
-  /* natural log scaling for periods between 0.2s and 1.0s */
-  static double subductionBasinPeriodScale(Imt imt) {
-    switch (imt) {
-
-      // scaling from 0.5s to 1.0s
-      case SA0P75:
-        return 0.585;
-
-      // scaling from 0.4s to 1.0s
-      // case SA0P5:
-      // return 0.243;
-      // case SA0P75:
-      // return 0.686;
-
-      // scaling from 0.2s to 1.0s
-      // case SA0P25:
-      // return 0.139;
-      // case SA0P3:
-      // return 0.252;
-      // case SA0P4:
-      // return 0.431;
-      // case SA0P5:
-      // return 0.569;
-      // case SA0P75:
-      // return 0.821;
-
-      default:
-        return 1.0;
-    }
-  }
-
 }

src/gov/usgs/earthquake/nshmp/gmm/ZhaoEtAl_2006.java

@@ -109,7 +109,6 @@ public abstract class ZhaoEtAl_2006 implements GroundMotionModel {
   private static final double MC_I = 6.3;
   private static final double MAX_SLAB_DEPTH = 125.0;
   private static final double INTERFACE_DEPTH = 20.0;
-  private static final double VS30_REF = 760.0;
 
   private static final Map<Imt, Range<Imt>> INTERPOLATED_IMTS = Maps.immutableEnumMap(
       ImmutableMap.of(
@@ -184,7 +183,7 @@ private static final class Coefficients {
   }
 
   private final Coefficients coeffs;
-  private final CampbellBozorgnia_2014.BasinAmp cb14basinAmp;
+  private final CampbellBozorgnia_2014 cb14;
 
   /* gmms = null if !flag */
   private final boolean interpolated;
@@ -194,7 +193,7 @@ private static final class Coefficients {
 
   ZhaoEtAl_2006(final Imt imt, Gmm subtype) {
     coeffs = new Coefficients(imt, COEFFS);
-    cb14basinAmp = new CampbellBozorgnia_2014.BasinAmp(imt);
+    cb14 = new CampbellBozorgnia_2014(imt);
     interpolated = INTERPOLATED_IMTS.containsKey(imt);
     interpolatedGmm = interpolated
         ? new InterpolatedGmm(subtype, imt, INTERPOLATED_IMTS.get(imt))
@@ -220,23 +219,20 @@ public final ScalarGroundMotion calc(GmmInput in) {
     double zSiteVs30 = siteTermStep(coeffs, in.vs30);
     double μZhao = calcMean(coeffs, isSlab(), zSiteVs30, in);
 
-    if (!Double.isNaN(in.z2p5) && basinEffect()) {
-
-      double cbSite = cb14basinAmp.basinDelta(in, VS30_REF);
-      double zSiteRock = siteTermStep(coeffs, VS30_REF);
-      double μRock = calcMean(coeffs, isSlab(), zSiteRock, in);
-      double μCb = μRock + cbSite;
-
-      /* Short-circuit lower values and short periods. */
-      int imtId = coeffs.imt.ordinal();
-      if ((μCb < μZhao) || (imtId < Imt.SA0P75.ordinal())) {
-        return DefaultScalarGroundMotion.create(μZhao, σ);
-      } else if (imtId < Imt.SA1P0.ordinal()) {
-        double μScaled = GmmUtils.scaleSubductionSiteAmp(coeffs.imt, μZhao, μCb);
-        return DefaultScalarGroundMotion.create(μScaled, σ);
+    /*
+     * Add CB14 deep basin amplification term if (1) z2p5 is non-NaN, (2) this
+     * instance is basin amplifying and (3) T>0.5s
+     */
+    if (!Double.isNaN(in.z2p5) &&
+        basinEffect() &&
+        coeffs.imt.ordinal() > Imt.SA0P5.ordinal()) {
+      double cbBasinTerm = cb14.deepBasinAmplification(in.z2p5);
+      if (coeffs.imt == Imt.SA0P75) {
+        cbBasinTerm *= 0.585;// log T scaling at 0.75s
       }
-      return DefaultScalarGroundMotion.create(μCb, σ);
+      μZhao += cbBasinTerm;
     }
+
     return DefaultScalarGroundMotion.create(μZhao, σ);
   }