Sunday 18 May 2025
Seismologists have long sought to better understand the inner workings of the Earth’s mantle, a vast and mysterious region that lies beneath our feet. Now, researchers have made a significant breakthrough in calculating the attenuation operator t*, a crucial component in understanding how seismic waves propagate through the mantle.
Attenuation refers to the decrease in amplitude of seismic waves as they travel through the Earth. This process is critical for understanding earthquake dynamics, as it can significantly impact the strength and distance that seismic waves are felt on the surface. T* represents the total path attenuation, which characterizes the amplitude decay of a propagating seismic wave.
Traditionally, scientists have calculated t* by integrating the inverse of the velocity-quality factor Q product along a ray path determined via ray tracing. However, this approach can be computationally intensive and may fail in mildly heterogeneous media. To overcome these limitations, researchers have developed a modified fast sweeping method (MFSM) that directly computes t* without explicitly determining the ray path.
The MFSM relies on two key steps: first, it calculates the traveltime field using a classic fast sweeping algorithm; second, it solves the governing equation for t*, discretizing the gradient of t* using an upwinding scheme derived from the traveltime gradient. By combining these two steps, the MFSM provides a more efficient and accurate method for computing t*.
In their recent study, researchers applied the MFSM to calculate t* in both Cartesian and spherical coordinates. They validated their results by comparing them with analytical solutions for uniform and constant-gradient models, as well as through grid refinement experiments. The effectiveness of the MFSM was demonstrated in a realistic velocity and attenuation model for North Island, New Zealand.
The significance of this breakthrough lies not only in its potential to improve our understanding of seismic wave propagation but also in its applications to earthquake tomography. By accurately calculating t*, researchers can better reconstruct the internal structure of the Earth’s mantle, which is critical for predicting earthquake behavior and mitigating seismic hazards.
This achievement marks a significant step forward in seismology, as it provides a more efficient and accurate method for computing t*. The MFSM has the potential to revolutionize our understanding of the Earth’s mantle and its role in shaping our planet’s surface. As researchers continue to refine this approach, we can expect to gain new insights into the inner workings of our dynamic planet.
Cite this article: “Breakthrough in Calculating Attenuation Operator t for Seismic Wave Propagation”, The Science Archive, 2025.
Seismology, Earth’S Mantle, Attenuation, Seismic Waves, Ray Tracing, Fast Sweeping Method, Traveltime Field, Gradient Scheme, Cartesian Coordinates, Spherical Coordinates
