Directivity-Based Probabilistic Seismic Hazard in California Interactive Maps
Directivity-Based Probabilistic
Seismic Hazard in California: Interactive Maps
Silvia Mazzoni, Linda Al Atik, Nick Gregor, Yousef Bozorgnia
Natural Hazards Risk and Resiliency Research Center (NHR3), UCLA
April 2023, doi:10.34948/N3101P

Directivity-Based PSHA was performed on 19,316 uniformly-distributed sites that span the entire state of California. The analysis results were processed and are presented visually in this dataset to give a better understanding of the geographic distribution of directivity effects at the uniform-hazard level. This map dataset contains maps of PSA with and without directivity, as well as the recommended directivity-amplification ratio that can be applied to your own PSHA results, which is computed from selected and weighted directivity models. The individual directivity-model ratios are also included in this dataset. Maps of the data used in the PSHA are also included in this dataset: Site-Specific Vs30, Z1.0, and Z2.5, and the UCERF-3 fault sources. Click here to retun to the project Main page

Instructions & Notes (click here to view/hide)
Notes:
  • Using Probabilistic Seismic-Hazard Analysis (PSHA), no-Directivity spectral values (PSA) were computed for all sites, all Vs30 cases (300-1100m/s + Site-Specific), all oscillator periods (0.01-10sec + PGV), and all return periods (52-10,000yr).
  • The directivitiy-based PSHA computed the PSA from the weighted average of selected directivity models.
  • The directivitiy-based PSHA was performed only for periods of 0.5 seconds and above, and for all return periods.
  • The directivitiy-based PSHA was performed at the reference Vs30 of 760 m/s for all sites, and other Vs30 (300-1100m/s) for a limited number of sites in the North-West region, where subduction sources influence the hazard significantly.
  • The recommended directivity-amplification ratio was computed from the ratio between of the with-directivity PSA (weighted average of directivity models) and the no-directivity PSA. A lower-bound value of 1.0 was set for this recommended value.
  • The recommended directivity-amplification ratio was computed for all sites at the reference Vs30 of 760 m/s, as well as at the other Vs30 (300-1100m/s, not site-specific) for a limited number of sites.
  • The with-directivity PSA was computed by factoring the no-directivity PSA at each Vs30 by the recommended directivity-amplification ratio corresponding to Vs760 for all sites, as well at at other Vs30 for a limited number of sites.(The recommended directivity-amplification ratio included the lower-bound value of 1.0).
  • The directivity-amplification ratio for the individual directivity models was computed from the ratio between of the with-directivity PSA for that particular model and the no-directivity PSA. No lower-bound constraints were applied. Directivity-amplification ratios for Vs30 other than Vs760 were computed only for a limited number of sites.
Instructions for the menus:
  • Use the pull-down menus to select the data you would like to visualize.
  • Menu options change depending on the quantity being visualized, the site class, and the oscillator period.
  • Not all menu combinations yield a map. If the map does not appear, the selected combination does not exist, please change your selection .
  • Click the button on the right of the menus to open the map in a new tab in full-page format.
Instructions for the map tools:
  • While on an interactive map, click a data point to access additional plots, such as hazard curves, uniform-hazard spectra, and deaggregation data.
  • Please allow time for your browser to load and render the maps.
  • Use the zoom button (top right) or you mouse wheel to zoom in/out.
  • Use the layer option (top right) to change background map as well as to toggle the display of the faults and pipelines.
  • Toggle the display of the fault and pipeline layers to bring these objects to the top of the map.
  • Click on the text (top right) to open a static map. The static maps are in jpg format are helpful for overall visualization and to include in a report.
  • Click the marker button (top left) to add you own marker to the map. You may add many markers.
  • Click the ruler (bottom left) to add a distance measure.
  • Toggle the minimap (bottom right) to visualize location of zoom window.
Instructional Video (click here to view/hide)

Quick Instructions:Always allow time for loading and rendering. Change menu selections (menu options change with different Oscillator Periods and Map Data). Zoom & Pan the map with your mouse and mouse wheel. Add markers (top left). Measure distances (bottom right). Change map layers (top right). Hover or click on a site for hazard data and plots.

Oscillator Period
Oscillator Period
Map Data
Map Data
Site Class Vs30
Site Class Vs30
Return Period
For questions, please contact the developer of this tool: Silvia Mazzoni smazzoni_AT_ucla_DOT_edu

How to cite this work:
Silvia Mazzoni, Linda Al Atik, Nick Gregor, Yousef Bozorgnia (2023): Directivity-Based Intensity-Measure Interactive Maps. The B. John Garrick Institute for the Risk Sciences. Dataset. https://doi.org/10.34948/N3101P (https://doi.org/10.34948/N3101P)