Geoscience Reference
In-Depth Information
nity for leveraging resources (ship time for maintenance, long-term funding for maintenance or
replacements) and is encouraged by the committee.
Similarly, there is great value in the continued coordination of U.S. tsunami-focused sea
level observation efforts with other U.S. and international programs interested in monitoring
sea level variability for other purposes, such as climate variability and climate change.
Conclusion:
Because coastal sea level stations have evolved from their primary mission to
serve a broad user community, their long-term sustainability has been enhanced.
The following are conclusions and recommendations related to the detection of tsunamis
with sea level sensors:
Assessment of Network Coverage for Tsunami Detection and Forecasting
Recommendation:
NOAA should assess on a regular basis the appropriateness of the
spatial coverage of the current DART sea level network and coastal sea level network (U.S.
and international), in light of constantly changing iscal realities, survivability experience,
maintenance cost experience, model improvements, new technology developments, and
increasing or decreasing international contributions. Especially, NOAA should understand
the vulnerabilities of the detection and forecast process to the following: (1) gaps in the
distribution of existing gauges and (2) failures of single or multiple stations.
A irst step in the assessment could be the establishment of explicit criteria, based on TWC
forecaster experience and on the arguments outlined for the DART site selection (Spillane et al.,
2008). An appropriate aid in this process would be simulations (e.g., Spillane et al., 2008) of the
effectiveness of the combined sea level networks, under numerous earthquake scenarios and
under various station failure scenarios. Such a study would also consider a region's tsunami-
producing potential, sensitivity analysis of source location, tsunami travel time, local popula-
tion density, timing for initial warning versus evacuation decision process for communities at
risk, and warning/evacuation time gained for additional station coverage. The contributions of
optimization algorithms to the network design process could be explored more fully as well.
Station Prioritization
Recommendation:
NOAA should prioritize the existing DART stations and coastal sea level
gauges (both U.S. and international) according to their value to tsunami detection and
forecasting for both U.S. territories and other AORs of the TWCs. Furthermore, this priority
list should be merged with the results from the network coverage assessment (above) to
determine the following: (1) maintenance priorities and schedules; (2) network expansion
priorities; and (3) identiication of critical stations that are not under U.S. control and may
require either augmentation with new U.S. gauges or operations and maintenance support.
An important aspect of this activity would be to develop and publish criteria, such as
the following examples: (1) value of a station for initial detection of a large tsunami near an
active fault zone, to maximize warning lead time; (2) value of a station for initial detection of
a medium to small tsunami, to mitigate false alarms; (3) value of a station for scaling forecast
