Hi-tech device to improve Tsunami and earthquake forecastDate: 26 November 2019 Tags: Disaster & Disaster Management
Scientists have successfully developed and tested a high-tech device that can detect the small movements and changes in the Earth’s seafloor which is often a precursor to deadly natural hazards, such as earthquakes, volcanoes and tsunamis.
The shallow water buoy device 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.
The seafloor geodesy system is an anchored spar buoy topped by high precision global positioning system (GPS). The system will be able to detect small changes in the stress and strain of the Earth’s crust.
The buoy’ orientation is measured using a digital compass that provides heading, pitch, and roll information that helps to capture the crucial side-to-side motion of the Earth that can be diagnostic of major tsunami-producing earthquakes.
Technology typically works best in the deeper ocean where there is less noise interference eventhough there are other sea floor measuring techniques.
Offshore strain accumulation and release processes are critical for understanding mega-thrust earthquakes and tsunamis.The experimental buoy rests on the sea bottom using a heavy concrete ballast and has been able to withstand several storms.
The 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.
The system is designed for subduction zone applications in the Pacific Ocean’s “Ring of Fire” where offshore strain accumulation and release processes are currently poorly monitored.
Earthquake is a sudden shaking of the ground caused by the passage of seismic waves through Earth’s rocks. Seismic waves are produced when some form of energy stored in Earth’s crust is suddenly released, usually when masses of rock straining against one another suddenly fracture and “slip.”
Earthquakes occur most often along geologic faults, narrow zones where rock masses move in relation to one another. The major fault lines of the world are located at the fringes of the huge tectonic plates that make up Earth’s crust.
P-waves, also known as primary waves or pressure waves, travel at the greatest velocity through the Earth. When they travel through air, they take the form of sound waves. They are the first waves to be recorded by a seismograph during an earthquake.They propagate through a material by alternately compressing and expanding the medium, where particle motion is parallel to the direction of wave propagation.
S-waves, also known as secondary waves, shear waves or shaking waves, are transverse waves that travel slower than P-waves. In this case, particle motion is perpendicular to the direction of wave propagation.
Surface waves are similar in nature to water waves and travel just under the Earth’s surface. They are typically generated when the source of the earthquake is close to the Earth’s surface.
Although surface waves travel more slowly than S-waves, they can be much larger in amplitude and can be the most destructive type of seismic wave. There are two basic kinds of surface waves:
Rayleigh waves, also called ground roll, travel as ripples similar to those on the surface of water.
Love waves cause horizontal shearing of the ground. They usually travel slightly faster than Rayleigh waves