Atkinson_2008p.java

package org.opensha2.gmm;

import static org.opensha2.gmm.GmmInput.Field.MW;
import static org.opensha2.gmm.GmmInput.Field.RJB;
import static org.opensha2.gmm.GmmInput.Field.VS30;
import static org.opensha2.gmm.GmmUtils.BASE_10_TO_E;
import static org.opensha2.gmm.GmmUtils.atkinsonTableValue;

import org.opensha2.gmm.GmmInput.Constraints;
import org.opensha2.gmm.GroundMotionTables.GroundMotionTable;

import com.google.common.collect.Range;

/**
 * Modified form of the relationship for the Central and Eastern US by Atkinson
 * (2008). This implementation matches that used in the 2014 USGS NSHMP and uses
 * table lookups instead of functional forms to compute ground motions. This
 * relation is commonly referred to as A08 Prime (A08').
 *
 * <p><b>Note:</b> Direct instantiation of {@code GroundMotionModel}s is
 * prohibited. Use {@link Gmm#instance(Imt)} to retrieve an instance for a
 * desired {@link Imt}.
 *
 * <p><b>Implementation note:</b> Mean values are clamped per
 * {@link GmmUtils#ceusMeanClip(Imt, double)}.
 *
 * <p><b>Reference:</b> Atkinson, G.M., 2008, Ground-motion prediction equations
 * for eastern North America from a referenced empirical approach—Implications
 * for epistemic uncertainty: Bulletin of the Seismological Society of America,
 * v. 98, n. 3, p. 1304–1318.
 *
 * <p><b>doi:</b> <a href="http://dx.doi.org/10.1785/0120070199">
 * 10.1785/0120070199</a>
 *
 * <p><b>Reference:</b> Atkinson, G.M., and Boore, D.M., 2011, Modifications to
 * existing ground-motion prediction equations in light of new data: Bulletin of
 * the Seismological Society of America, v. 101, n. 3, p. 1121–1135.
 *
 * <p><b>doi:</b> <a href="http://dx.doi.org/10.1785/0120100270">
 * 10.1785/0120100270</a>
 *
 * <p><b>Component:</b> horizontal (not clear from publication)
 *
 * @author Peter Powers
 * @see Gmm#ATKINSON_08_PRIME
 */
public final class Atkinson_2008p implements GroundMotionModel {

  static final String NAME = "Atkinson (2008) Prime";

  static final Constraints CONSTRAINTS = Constraints.builder()
      .set(MW, Range.closed(4.0, 8.0))
      .set(RJB, Range.closed(0.0, 1000.0))
      .set(VS30, Range.closed(760.0, 2000.0))
      .build();

  static final CoefficientContainer COEFFS = new CoefficientContainer("A08P.csv");

  private static final double SIGMA = 0.3 * BASE_10_TO_E;

  private final double bcfac;
  private final Imt imt;
  private final GroundMotionTable table;

  Atkinson_2008p(final Imt imt) {
    this.imt = imt;
    bcfac = COEFFS.get(imt, "bcfac");
    table = GroundMotionTables.getAtkinson08(imt);
  }

  @Override
  public final ScalarGroundMotion calc(final GmmInput in) {
    double r = Math.max(in.rJB, 0.11);
    double μ = atkinsonTableValue(table, imt, in.Mw, r, in.vs30, bcfac);
    return DefaultScalarGroundMotion.create(GmmUtils.ceusMeanClip(imt, μ), SIGMA);
  }

}