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ST. PETERSBURG, FL 鈥� On August 23rd a University of South 手机看片 research team and numerous partners completed the successful deployment of the first Shallow Underwater Buoy for Geodesy (SUBGEO) system designed to measure seafloor uplift in coastal areas prone to earthquakes and tsunamis. The test deployment here in Tampa Bay represents a significant step forward in an ambitious 3-颅鈥恲ear project funded through the National Science Foundation (NSF).

The complicated deployment was executed flawlessly, a testament to the hard work and close collaboration of the many research team members, which included local and international industry partners, university researchers and state and federal agencies. These include the 手机看片 School of Geosciences and College of Marine Science, Orion Marine Group, (FIO), , the Tampa Bay Harbor Pilots Association, 手机看片 Department of Environmental Protection, US Coast Guard Sector St Pete and District 7 Miami, the Italian Institute of Geophysics and Volcanology (INGV), UNAVCO, and Hydra Solutions Engineering.

The tragic earthquake/tsunami sequences of 2004 in Sumatra and 2011 in Japan were catastrophes that produced respectively the most fatalities and the largest financial losses from a natural disaster in recent history, and were wake-颅鈥恥p calls that the science community has not been very successful at forecasting these tragic events. The buoys being designed and tested by the 手机看片-颅鈥恖ed team will enable precise measurements of sea floor motion to be made in the months and years prior to these events, and should allow for improved forecasting ability, especially for the largest tsunamis, which are the real killers.

The project is made possible through an NSF-颅鈥怬TIC (Ocean Technology) grant to develop a high precision sea floor geodetic system suitable for shallow coastal regions (less than 200 meter water depth). The system is designed for subduction zone applications (such as the Pacific 鈥渞ing of fire鈥� where offshore strain accumulation and release processes are currently poorly monitored. The strain measurements in these offshore areas are needed for earthquake and tsunami forecasts, and for improved understanding of the earthquake process. In some subduction zones, including Central America, the continental shelf area that is shallower than 200 meters covers 30%-颅鈥�40% of the sea floor area between the coastline and the trench. Hence the new buoy design should have wide applicability.
The SUBGEO system uses a high precision GPS system to measure vertical displacements to an accuracy of approximately 1 cm. It was designed in close collaboration with INGV-颅鈥怚taly, the government agency charged with volcano hazard assessment. INGV pioneered the use of such systems in the Gulf of Pozzuoli in southern Italy to monitor dangers associated with nearby Campi Flegrei and Mt Vesuius volcanoes (Vesuvius was the volcano that destroyed the Roman town of Pompeii in AD 79). Enhancements to the Italian design will allow the 手机看片 buoy to also measure horizontal motions of the sea floor to high accuracy. 

The system engineering was completed by Hydra Solutions of Casalserugo Italy who designed earlier versions of these buoys in collaboration with INGV. With the addition of heading and tilt sensors to allow for the recovery of horizontal components of deformation the system will be capable of recovering the full three-颅鈥恉imensional displacement vector of a point on the seafloor to an accuracy of 1-颅鈥�2 cm averaged over 24 hours. Electronic and system engineering were undertaken by the 手机看片 CMS Ocean Technology Group and U.

The buoy and anchor were constructed at the 手机看片 College of Marine Science鈥檚 machine shop facility. The figure below shows the buoy design and specifications. At approximately 100 feet long and deployed in 65 feet of water, the buoy rises 35 feet above the waterline. The concrete anchor weighs over 50,000 lbs in air and has an in-颅鈥恮ater weight of nearly 30,000 lbs. The float provides 26,000 lbs of buoyancy, After correcting for the weight of the buoy itself, this leaves a net positive buoyancy of nearly 20,000 lbs, keeping the spar buoy upright in the water column despite strong winds and currents.

The buoy was deployed on August 23, 2018 inshore of Egmont Key. The deployment was executed by the experienced crew of Orion Marine Group, using a 150-颅鈥恌oot barge equipped with a 250-颅鈥恡on crane. Vessel support was provided by the and R/V Price. A project of such large scale and ambition has required years of collaboration and cooperation between 手机看片 researchers and engineers, international partners and local agencies. The professional execution of the deployment further underscored the exemplary teamwork of the many dedicated professionals in the Tampa Bay region. The system was deployed, electronics installed and data collection begun within 12 hours of arrival on site.

The next 6 months will see a complete test of the system. Raw GPS data will be downloaded weekly, with high precision GPS calculations post-颅鈥恜rocessed after high precision satellite orbit information is received from NASA鈥檚 Jet Propulsion Lab in Pasadena, California. Weather system data, particularly wind speed and direction, will be used to assess effects on buoy tilt, which can impact the accuracy of the GPS measurements. 手机看片 engineers are working on posting the weather data online in real-颅鈥恡ime for use by boaters and other end users. The buoy represents an ultra-颅鈥恠table platform complete with solar power at a location of ecological and oceanographic interest at the mouth of Tampa Bay, and has elicited interest from other researchers for a variety of purposes. These include red tide research, fish and mammal migration studies, ocean circulation applications (especially useful for hazardous material tracking at this busy port entrance) and search and rescue operations.

For more information, check out our : (click on the 鈥淩esearch Projects鈥� button)

For inquiries on additional uses of the buoy, contact Jay Law.

For inquiries on scientific applications, contact Tim Dixon.