GAO: U.S. tsunami detection buoys are costly, difficult, and not always reliable

Published 3 May 2010

A network of 39 buoys makes up the early-warning system to protect 767 U.S. coastal communities at risk of tsunamis; maintaining the system is expensive — it consumes 28 percent o the National Oceanic and Atmospheric Administration’s budget — and the sensors are not always reliable

The National Oceanic and Atmospheric Administration (NOAA) is facing difficulties in maintaining its network of expensive high-tech tsunami detection buoys, according to a Government Accountability Office (GAO) report released last Wednesday (.pdf). Known as the Deep-ocean Assessment and Reporting of Tsunamis (DART) program, this network of thirty-nine buoys makes up the early-warning system to protect 767 U.S. communities at risk of tsunamis — large, devastating waves, typically generated by seismic events or undersea landslides — that can destroy coastal and island communities.

Matthew Harwood writes that the last significant tsunami hit U.S. soil in September 2009, when a series of waves hit American Somoa, killing 190 people and wiping out coastal infrastructure. In February, NOAA scientists initially feared Hawaii could get pounded by a massive tsunami after the 8.8 earthquake off Chile, but fortunately only 3-foot tsunami waves hit the state’s shores.

The DART system consists of surface-level buoys connected by mooring lines to ocean-floor-anchored recording devices that monitor seismic activity. Data from the recording devices is transmitted to a satellite in 15-minute intervals until an event triggers transmissions at 15-second intervals. The satellite then delivers that data to two tsunami warning centers based in Alaska and Hawaii, respectively. The centers are responsible for warning U.S. coastal states, island territories, and more than 90 countries when a tsunami threat occurs.

Harwood notes that the buoys are expensive and temperamental. Last year, DART operation and maintenance cost $12 million, or 28 percent, of NOAA’s total tsunami budget for the fiscal year.

Reliability is another problem,” he writes. “At any one time, the NOAA reported that data from the buoys was available about 84 percent of the time and one to two buoy outages occur each month.”

There are two primarily reasons for this: human error and “Old Man Winter.”

Most buoy outages occur due to problems with mooring lines. “According to data from NOAA’s National Data Buoy Center… failure of mooring lines accounted for almost 60 percent of DART buoy outages from December 2005 to November 2009,” the GAO reports. “Center officials told us that mooring lines fail for a variety of reasons, including ship collisions and vessels that tie up to a buoy.”

Winter makes it difficult to keep the buoys working because the NOAA can not make its regular maintenance rounds because of harsh ocean conditions.

The NOAA told the GAO it wants to improve its buoy network’s data availability rate significantly. Currently the NOAA is trying to identify stronger mooring materials while it also explores moving some buoys to less hostile waters.

These improvements are critical, the GAO explains, because “[w]hen DART buoys are out of service, they cannot detect tsunamis or transmit data to the tsunami warning centers.”