Geoscience Reference
In-Depth Information
FIGURE 4.1
Data from approximately 350 seismic stations are accessed by the TWCs. SOURCE: West
Coast/Alaska Tsunami Warning Center, NOAA.
to be reliable, with current (2009-2010) data return rates of 89 percent. The GSN is suficiently
robust to support warnings for events far from the recording devices and provides good global
coverage (U.S. Indian Ocean Tsunami Warning System Program, 2007). The USGS was provided
funding through the Emergency Supplemental Appropriations Act for Defense, the Global War
on Terror, and Tsunami Relief, 2005 (P.L. 109-13) to expand and upgrade the GSN for tsunami
warning. For redundancy, the TWCs also receive seismic data from many other vendors on
multiple communication paths. Given the wide array of uses of the existing seismic networks,
GSN can generally be viewed as a data network that is likely to be continued, well-maintained,
and improved over the long-term. A future broad upgrade of seismometers in the GSN may be
important for tsunami warning.
Nevertheless, the TWCs' heavy reliance on data networks from partnering agencies ex-
poses them to some degree of vulnerability to potential losses of data availability in the future.
For example, much of the seismic data crucial to the operation of the TWCs comes from GSN
stations whose deployment and maintenance have been and are currently funded primarily
from NSF cooperative agreements with IRIS, renewable every ive years. The Scripps Institu-
tion of Oceanography's (SIO's) International Deployment of Accelerometers (IDA) project with
