Worldwide Seismic Design Tool Documentation

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Introduction

This web tool provides earthquake shaking parameters worldwide that are needed for seismic design of structures using the International Building Code (§1613) and similar standards (e.g., the ASCE/SEI 7 Standard and the U.S. Department of Defense Unified Facilities Criteria). More specifically, it provides SS and S1 (spectral response acceleration at 0.2 and 1.0 seconds, respectively, for 5% of critical damping) values derived using seismic hazard data from numerous sources. All values provided by this application are for Site Class B.

Important Note: Users should always defer to the design standards of the jurisdiction in which the project will be built. The design values provided by this tool never supersede those provided by the governing local/national design codes or a site-specific analysis. Furthermore, the seismic design procedures of local or national building codes often require the use of design parameters other than SS and S1. The user is responsible for knowing which seismic design parameters are required by the applicable design code.

If you do not find the answer to your question here, please email us at wwdesignmaps@usgs.gov for a prompt reply.

Motivation for this tool

The USGS has received numerous requests for SS and S1 values at sites around the world. The Worldwide Seismic Design Tool collects published seismic design parameter values from national, regional, and global studies and makes them available from one tool.

Help using the tool

Specifying Project Site

Users can specify a project site by entering the site latitude into the “Latitude” input box (#1, in the below image), entering the site longitude into the “Longitude” input box (#2), and clicking the “Set Location” button (#3). Latitudes should be in the range of -90 to 90 decimal degrees, with negative values for the Southern Hemisphere. Longitudes should be between -180 to 180 decimal degrees, with negative values for the Western Hemisphere.

Figure: Application user interface and input/output

The blue location marker (#4) will automatically move to the site corresponding to the user-specified latitude and longitude, and the output window (#5) will appear. Alternatively, users can click and drag the blue location marker to the site of interest. A user can pan and zoom the map by using the zoom controls (#6), by dragging the map, by double-clicking on a location, or by using a mouse scroll wheel (if present).

Finally, users can access seismic design parameter values for a limited number of individual sites by clicking on the red pin icons on the map.

Hovering over the map layers icon (#7) will reveal additional map visualization options (such as street or satellite imagery).

Underlying sources of seismic design parameter values

Global

The USGS has incorporated global-scale sets of seismic design parameter values into the tool. To date, all global-scale sets of parameter values referenced by the tool are based upon peak ground acceleration (PGA) values with a 10% probability of exceedance in 50 years from the Global Seismic Hazard Assessment Program (GSHAP) study. Please see the “Sources of SS and S1 values” table below for detailed information on how these global-scale sets of parameter values were converted to the spectral acceleration values provided by the application.

National or Regional scale

Shaded red boxes overlaid on the map (see Haiti, for example) indicate national/regional areas for which the USGS has developed or obtained region-specific seismic design parameter values. These values are provided in addition to the global-scale values described above. Detailed information on how these values were incorporated into the application is provided in the “Sources of SS and S1 values” table below.

Individual Sites

The USGS has also incorporated seismic design parameter values assigned to individual sites into the tool. Locations for which such values are available are denoted on the application map by small pins with red tops.

These parameter values can be accessed simply by clicking on the pin corresponding to the site of interest. The parameter values for individual sites provided through this tool are generally pulled from government design documents, such as the U.S. Department of Defense Unified Facilities Criteria 3-301-01: Structural Engineering or the Geologic Survey of Canada Open File 5814 documents. More information on these documents is provided in the “Sources of SS and S1 values” table below.

Output Window

Summary Tab

The output window (#5, in the image above) will appear automatically once the user has specified a site of interest. The window is organized into a series of tabs. The “Summary” tab presents the user with a quick overview of all of the seismic design parameter values available through the tool for the specified site. The first column lists the title of each study referenced for the site. The “SS” and “S1” columns provide the spectral acceleration values experienced by a structure with a period of 0.2s and 1.0s, respectively. The “Classification” column provides one of three classification colors: Green, Yellow, or Red. A Green classification indicates that the SS and S1 values are from a recently completed probabilistic seismic hazard assessment (PSHA) performed specifically for the nation or region encompassing the site. A Yellow classification is assigned to SS and S1 values from a PSHA that has been superseded by a more recent study. A Red classification indicates that the SS and S1 values are from a study that was either not a PSHA or that was a PSHA performed for an area much larger than a nation/region.

Study-specific Tabs

Next to the Summary tab will be displayed one or more study-specific tabs. Each of these tabs provides additional information about the parameter values derived from one study listed on the Summary tab, such as the edition of the International Building Code with which the provided values are compatible. A link to this Documentation page is also included.

“Which values should I use?”

At many sites around the world, SS and S1 values are available from several studies. The Worldwide Seismic Design Tool reports SS and S1 values from all available studies in an unordered list. Any consistency in values does not necessarily suggest convergence towards one "correct" set of values; some referenced studies are heavily based upon other sources referenced by this tool, so the values from such studies are inherently coupled. Users are responsible for deciding which values to incorporate into their designs.

Sources of Seismic Design Parameter Values

Short Title Source Notes on Underlying Study
UFC + GSHAP Global Seismic Hazard Assessment Program (Worldwide) Published in 1999. These are 2%-in-50-year spectral response acceleration values. They are rough approximations based on the probabilistic 10%-in-50-year peak ground acceleration (PGA) values from the Global Seismic Hazard Assessment Program (GSHAP). The USGS converted the 10% probability of exceedance in 50 years PGA values provided by GSHAP to SS and S1 by: 1) multiplying by 2 to approximate 2%-in-50-year PGA values, and then...2) multiplying by 2.5 and 1.0 to approximate SS and S1, respectively, to estimate the SS and S1 values provided here. As a result of these approximations, the output is classified as Red.
EU Code + GSHAP Lubkowski, Deriving the Seismic Action for Alternative Return Periods According to Eurocode 8 (Worldwide) Published in 2010. These are 2%-in-50-year spectral response acceleration values. They are rough approximations based on the probabilistic 10%-in-50-year peak ground acceleration (PGA) values from the Global Seismic Hazard Assessment Program (GSHAP). The GSHAP values were converted to 2%-in-50-year PGA values, per Eurocode 8 Equation 2.1. The k-factor needed for Equation 2.1 was calculated using the methodology developed by Lubkowski (2010). The resulting 2%-in-50-year PGA values were then multiplied by 2.5 and 1.0, respectively, to estimate the SS and S1 values provided here. As a result of these approximations, the output is classified as Red.
GSC + GSHAP GS of Canada Open File 5814 (Worldwide) Published in 2008. These are probabilistic 2%-in-50-year spectral response acceleration values. They are directly from Table 7 of the GSC report entitled "Estimated Seismic Design Values for Canadian Missions Abroad." For Canadian locations, they are based on (with adjustments) the 2005 National Building Code of Canada (NBCC), which references spectral acceleration values directly based on a probabilistic seismic hazard assessment. Because the 2005 NBCC has been superseded by the 2010 NBCC (not referenced here), the output for these sites is classified as Yellow. For sites outside Canada and the U.S.A., the GSC based the values on the Global Seismic Hazard Assessment Program map. The output for these sites is classified as Red.
UFC '13 [Unified Facilities Criteria 3-310-01, 2013 and 2014] (http://www.wbdg.org/ccb/DOD/UFC/ufc_3_301_01.pdf) (Outside the U.S. & its Territories) Published in 2013 and 2014. These values are directly from Table F-3 of the 1-June-2013 and 15-May-2014 editions of the U.S. Department of Defense (USDoD) Unified Facilities Criteria 3-301-01: Structural Engineering design document. These values are 1%-probability-of-structural-collapse-in-50-years spectral acceleration values, which are compatible with the 2012 International Building Code. Most values from Table F-3 were initially based upon 10%-in-50-year PGA values from GSHAP; therefore, these output values are classified as Red. Values for a subset of sites are based upon recent regional probabilistic seismic hazard assessments; these are classified as Yellow or Green, depending upon the site. The values for another subset of sites are based upon site-specific studies commissioned by the U.S. military; these too are classified as Green or Yellow, depending upon the site.
UFC '10 Unified Facilities Criteria 3-310-01, 2010 (Outside the U.S. & its Territories) Published in 2010, updated in 2012. These are probabilistic 2%-in-50-year spectral response acceleration values. They are directly from Tables F-2 and G-1 of the 31-January-2012 (with Change 3) edition of the U.S. Department of Defense (USDoD) Unified Facilities Criteria 3-301-01: Structural Engineering design document. These values are compatible with the 2006 and 2009 International Building Code. Most values from Tables F-2 and G-1 were approximated in the same manner as those provided on the "GSHAP" tab; therefore, these output values are classified as Red. Values for a small subset of sites are based upon site-specific studies commissioned by the U.S. military; these are classified as Green or Yellow, depending upon the site.
NZS NZS 1170.5:2004 (New Zealand sites) Published in 2004. These values have been calculated according to Equation 3.1(1) of the New Zealand Standard 1170.5:2004, for NZS site subsoil class B (rock) and an annual probability of exceedance of 1/2500 (nearly equivalent to 2%-in-50-year exceedance probability). The spectral acceleration values are directly based on a country-specific probabilistic seismic hazard assessment. However, this assessment has since been superseded by a more recent version. For these reasons, the output for these sites is classified as Yellow.
USGS ’10 [USGS Open-File Report 2010-1067] (http://pubs.usgs.gov/of/2010/1067/) (Haiti) Published in 2010. These values have been derived in the same way as the U.S. values in the 2009 and earlier editions of the International Building Code. That is, they represent the minimum of probabilistic (2%-in-50-year) and corresponding deterministic spectral response acceleration values. Because the SS and S1 values were calculated directly by a probabilistic seismic hazard assessment, and they are less than 10 years old, the output is classified as Green.
USGS '07 [USGS Open-File Report 2007-1137] (http://pubs.usgs.gov/of/2007/1137/) (Afghanistan) Published in 2007. These are probabilistic 2%-in-50-year spectral response acceleration values. Corresponding deterministic values that the International Building Code would use to cap these probabilistic values (where they are greater than 1.5g and 0.6g, respectively), have not yet been computed for this region. Because the SS and S1 values were calculated directly by a probabilistic seismic hazard assessment, and they have not been superseded by another study, the output is classified as Green.
USGS '07 USGS Administrative Report Sept. 30, 2007 (Southeast Asia) Published in 2007. These are probabilistic 2%-in-50-year spectral response acceleration values. Corresponding deterministic values that the International Building Code would use to cap these probabilistic values (where they are greater than 1.5g and 0.6g, respectively), have not yet been computed for this region. The SS and S1 values were calculated directly by a probabilistic seismic hazard assessment, though the study has been superseded, so the output is classified as Yellow.

Please contact us with information about additional sources of seismic design parameter values.

Spatial interpolation

Bi-linear Interpolation Graphic

Figure: Example gridded dataset (black dots) and the four types of requested locations (red dots)

The tool uses a bilinear interpolation method to return the SS and S1 values associated with the location from each gridded set of underlying parameter values. A selected location falls into one of four categories (labeled in the figure above):

  • Exact Grid Point (P1): The requested site lies on a grid point in the underlying set of values. The application returns the exact SS and S1 values at the grid point.
  • Between Two Longitudes (P2): The requested site lies on a latitude line that is part of the underlying grid, but the site is between two gridded longitude lines. The tool returns SS and S1 values linearly interpolated between the two gridded points with the same latitude on either side of the site.
  • Between Two Latitudes (P3): The requested site lies on a longitude line that is part of the underlying grid, but the site is between two gridded latitude lines. The tool returns SS and S1 values linearly interpolated between the two gridded points with the same longitude on either side of the site.
  • Bounded by Four Grid Points (P4): The requested site lies inside a box bounded by four grid points in the underlying grid. The application performs a bilinear interpolation. First the SS and S1 values are linearly interpolated between the northern pair of grid points and between the southern pair. Then these interpolated values are again interpolated to find the SS and S1 values at the requested latitude.

Troubleshooting Tips

If the application fails to load

A failure to load would most likely result from the use of an incompatible browser. The USGS maintains its web tools for compatibility with the current version of each major browser, plus the previous edition (e.g., Internet Explorer 11 and 10, respectively). If the problem persists, please contact us at wwdesignmaps@usgs.gov and we can work through the problem.

If you use Google Chrome and the application fails to load, please [follow these steps] (https://geohazards.usgs.gov/secure/designmaps/ww/application.php).

Error Messages

"No point data exist for this location" – Unfortunately none of the sources referenced by this application provides seismic design parameter values for the specified site. This is most likely to be true in sparsely populated areas (e.g., desert or tundra), in ocean areas, and near the poles.

Copyright Information

This software is in the public domain. Please see the [official USGS copyright policy] (http://www.usgs.gov/visual-id/credit_usgs.html#copyright) for more information.