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that has been developed over the past decades. The committee acknowledges the foregoing
states' concerns, in addition to their long-term investments in inundation model development
and tsunami source research.
Alternatively, a model accreditation system might be designed to ensure greater adherence
to guidelines, formal criteria and procedures, and minimum quality standards developed by the
MMS (e.g., OAR PMEL-135). This model accreditation system could be administered by a body
that uses peer-review or another objective and transparent process to judge whether modeling
efforts meet these aforementioned guidelines, criteria, and minimum quality standards. Ideally,
NTHMP would only make funding available to states that have been oficially accredited. This
body administering the accreditation system needs to be free of conlicts of interest.
Conclusion:
The development and use of inundation models is not occurring in a
coordinated or standardized fashion across the NTHMP.
Each NTHMP member state
independently selects the tsunami source, bathymetric and topographic data, and
numerical code when modeling inundation to create tsunami hazard maps. This state-
based approach to tsunami inundation modeling, coupled with inadequate coordination
and consensus among NTHMP modelers and no external peer-review, has created
signiicant disparities in the methods, criteria, and judgments employed in tsunami
inundation modeling and resulting tsunami hazard maps. There is also inadequate
understanding and discussion on the cost, beneits, and utility of employing new higher
order models over existing models. Disparities in modeling approaches and source
determination also hamper the nation's ability to compare societal risk to tsunami hazards.
Solving these issues may be dificult within the current MMS structure, given the potential
conlicts of interest of the state tsunami modelers that comprise the subcommittee. An
alternative approach might need to be identiied, such as an accreditation system.
Recommendation:
The NTHMP should seek ways to reduce needless disparities among
states and territories in their approaches to inundation modeling. Inundation from tsunami
threats that transcend political boundaries (e.g., Cascadia subduction zone) should be
modeled consistently across state lines, instead of the current state-centric approaches. To
eliminate these unnecessary and costly differences in inundation modeling approaches,
the committee recommends that inundation modeling be conducted consistently
across state lines and be executed through a cooperative partnership among NOAA, the
USGS, and NTHMP members, and not by the individual NTHMP members as is the current
practice. The committee proposes the following strategy:
•
First, NOAA could take a lead to organize a workshop to establish community
hydrodynamic models used for tsunami inundation modeling: one set for co-seismic
tsunami sources and another set for landslide tsunami sources. To ensure continuing
community support and improvement, the models—including full documentation and
source code—should be accessible in a virtual repository that will be maintained by
NOAA. The repository should host a discussion forum.
