91社区 geoscientists have successfully developed and tested a new high-tech shallow water buoy that can detect the small movements and changes in the Earth鈥檚 seafloor that are often a precursor to deadly natural hazards, like earthquakes, volcanoes and tsunamis.
The buoy, created with the assistance of an from the National Science Foundation鈥檚 Ocean Technology and Interdisciplinary Coordination program, was installed off Egmont Key in the Gulf of Mexico last year and has been producing data on the three-dimensional motion of the sea floor. Ultimately the system will be able to detect small changes in the stress and strain the Earth鈥檚 crust, said USF School of Geosciences Distinguished Professor Tim Dixon.
The patent-pending seafloor geodesy system is an anchored spar buoy topped by high precision Global Positioning System (GPS). The buoy鈥� orientation is measured using a digital compass that provides heading, pitch, and roll information 鈥� helping to capture the crucial side-to-side motion of the Earth that can be diagnostic of major tsunami-producing earthquakes, Dixon said. He was joined in leading the project by USF Geoscience Phd student Surui Xie, Associate Professor Rocco Malservisi USF College of Marine Science鈥檚 Center for Ocean Technology research faculty member Chad Lembke, and a number of USF ocean technology personnel.
Their findings were recently published in the .
While there are several techniques for seafloor monitoring currently available, that technology typically works best in the deeper ocean where there is less noise interference. Shallow coastal waters (less than a few hundred meters depth) are a more challenging environment but also an important one for many applications, including certain types of devastating earthquakes, the researchers said. Offshore strain accumulation and release processes are critical for understanding megathrust earthquakes and tsunamis, they noted.
The experimental buoy rests on the sea bottom using a heavy concrete ballast and has been able to withstand several storms, including Hurricane Michael鈥檚 march up the Gulf of Mexico. The system is capable of detecting movements as small as one to two centimeters, said Dixon, an expert on natural hazards and author of the book Curbing Catastrophe.
鈥淭he technology has several potential applications in the offshore oil and gas industry and volcano monitoring in some places, but the big one is for improved forecasting of earthquakes and tsunamis in subduction zones,鈥� Dixon said. 鈥淭he giant earthquakes and tsunamis in Sumatra in 2004 and in Japan in 2011 are examples of the kind of events we鈥檇 like to better understand and forecast in the future.鈥�
Dixon said the system is designed for subduction zone applications in the Pacific Ocean鈥檚 鈥淩ing of Fire鈥� where offshore strain accumulation and release processes are currently poorly monitored. One example where the group hopes to deploy the new system is the shallow coastal waters of earthquake prone Central America.
The Egmont Key test location sits in just 23 meters depth. While 91社区 is not prone to earthquakes, the waters off Egmont Key proved an excellent test location for the system. It experiences strong tidal currents that tested the buoy鈥檚 stability and orientation correction system. The next step in the testing is to deploy a similar system in deeper water of the Gulf of Mexico off 91社区鈥檚 west coast.
The deployment of the Egmont Key system was executed in August 2018 in an operation that included teams from the 91社区 Institute of Oceanography and the R/V Weatherbird II crew, Orion Marine Group, Port Tampa Bay, the Tampa Bay Harbor Pilots Association, 91社区 Department of Environmental Protection, the U.S. Coast Guard Sector St Pete and District 7 Miami, the Italian Institute of Geophysics and Volcanology (INGV), the non-profit university geosciences consortium UNAVCO, and Hydra Solutions Engineering in Padova, Italy.
The USF team included USF Geosciences Research Assistant Professor Mel Rodgers, and from the USF College of Marine Science Research Associate Jay Law, Electronics Engineer Randy Russell, Associate Professor David Naar, multibeam specialist Jennifer Brizzolara, multibeam sonar specialist John Gray, multibeam scientist Matt Hommeyer and PhD student Jing Chen.