These files are electronic versions of Figure 1 and the data listed in Appendices A, B (both csv files), Appendix C (a txt file) and a FORTRAN subroutine for calculating the local magnitude adjustment (dML) for a new station-component.
Figure 1. This high-resolution (600 dpi) map shows the study area including candidate earthquakes (small gray circles), candidate stations with both broadband and strong motion sensors (large colored circles) and the 50km x 50 km grid (ditted lines) used for selecting the earthquakes. Stations with only strong motion sensors are not shown on the map for clarity but their adjustments are given in the CISN dML adjustments file. The colors of the vertical (N component) and horizontal (E component) lenses superimposed on the station symbols give the magnitude of the CISN SNCL adjustment (dML) as shown on the color scale. The magnitude of the CISN dML correlated with the competence of the soil/rock on which the station is sited. Hard rock sites have large positive dML values and very soft soil sites have negative dML values. Stations in the LA Basin are shown in the inset at a larger scale.
Candidate Events. The first column is the 50km by 50 km grid square where the event is located. The events were extracted from the ANSS composite catalog.
CISN dML Adjustments. Initial set of 666 CISN dML adjustments determined using the 2000-2006 data set analyzed in this study. The table entries are (SNCL, dML, standard error) triplets.
CISN -logAo(r) FORTRAN Function. Double precision FORTRAN function which calculates the CISN -logAo(r) attenuation function at radial distance r in km.
CISN FORTRAN Subroutine. Double precision FORTRAN subroutine which calculates the local magnitude adjustment (dML) for a new SNCL (station-network-component-location). The algorithm determines the dML for a new SNCL using a median value statistic by comparing the differences between the ML estimates for the new SNCL and the ML estimates for CISN stations with known SNCL dML. For robustness, it is highly recommended that the new SNCL have recorded at least 30 events with amplitudes in an appropriate WA amplitude range and also that there are at least 200 differential ML observations used in the calculation of the new SNCL dML. The algorithm returns with the 'ans' argument set to 1 if these criteria are not met.
