The Washington State Building Code Council approved amendments to the tsunami code (International Building Code Section 1615) which adopted the Department of Natural Resources’ (DNR) published tsunami inundation maps into code. This was an update to the 2018 code amendments that only had partial coverage of tsunami inundation mapping for the State. The code also indicates that practitioners utilize a geodatabase containing information pertinent to engineering and design calculations. This geodatabase is visualized on the DNR online TDZ tool (https://www.dnr.wa.gov/wa-tdz) as an implementation tool to aid in utilizing the tsunami data. However, following feedback from practitioners who are utilizing the tool, DNR realized that the inundation elevation values within the geodatabase and displayed on the online TDZ tool are not reporting correctly in places where land levels are expected to change from earthquake subsidence. The source data from published tsunami inundation mapping for inundation depth (downloadable from the TDZ website) is correct and remains usable to practitioners. Further, practitioners indicated that the DNR online TDZ tool could be made more useful by displaying additional datasets for inundation depth and subsidence.
Considering the inundation elevation dataset has inaccurate values in areas of earthquake subsidence the DNR has taken down the downloadable geodatabase and online TDZ tool to prevent misuse of its potentially incorrect reported values. DNR's intent is that the inundation elevation dataset be corrected, and additional datasets for inundation depth and subsidence be added before the geodatabase and online TDZ tool are brought back online. When complete, the geodatabase's metadata, online TDZ tool, and TDZ website will have amended text documenting and dating the changes so practitioners are aware of the update.
Corrections and Enhancements to the 2021 Tsunami Design Zone (a WSG presentation)