Azimuthal anisotropy (black dashed lines revealing the fast direction of wave speeds) in the mantle at 200 km depth plotted on top of vertically polarized shear wave speed perturbations (dVsv) after 20 versions based on international azimuthally anisotropic adjoint tomography. Red and blue colors represent the slow and fast shear wave speeds with regard to the mean design which are usually associated with hot and cold materials, respectively.
High resolution lighting of Earths interior to the planets core with 3D global numerical simulations.
Earthquakes do more than buckle streets and fall buildings. Seismic waves produced by earthquakes pass through the Earth, acting like a giant MRI machine and providing ideas to what lies inside the world.
Seismologists have actually established techniques to take wave signals from the networks of seismometers at the Earths surface and reverse engineer features and attributes of the medium they travel through, a procedure called seismic tomography.
For years, seismic tomography was based upon ray theory, and seismic waves were dealt with like light rays. This served as a respectable approximation and caused significant discoveries about the Earths interior. But to enhance the resolution of current seismic tomographic designs, seismologists need to take into account the complete intricacy of wave proliferation using numerical simulations, known as full-waveform inversion, states Ebru Bozdag, assistant teacher in the Geophysics Department at the Colorado School of Mines.
Marsquake– Cerberus Fossae event (Mw 3.1). The visualization shows the speed of the seismic waves (vertical component). Scientists used Frontera to imitate the occasion, in cooperation with the NASA InSight objective. Credit: Daniel Peter, KAUST
” We are at a phase where we need to avoid approximations and corrections in our imaging methods to construct these models of the Earths interior,” she said.
Bozdag was the lead author of the very first full-waveform inversion model, GLAD-M15 in 2016, based upon complete 3D wave simulations and 3D information level of sensitivities at the international scale. The model used the open-source 3D global wave proliferation solver SPECFEM3D_GLOBE (easily available from Computational Infrastructure for Geodynamics) and was developed in collaboration with researchers from Princeton University, University of Marseille, King Abdullah University of Science and Technology (KAUST), and Oak Ridge National Laboratory (ORNL). The work was admired in journalism. Its follower, GLAD-M25 (Lei et al. 2020), came out in 2020 and brought popular features like subduction zones, mantle plumes, and hotspots into view for further conversations on mantle characteristics.
” We revealed the feasibility of utilizing complete 3D wave simulations and data level of sensitivities to seismic criteria at the global scale in our 2016 and 2020 papers. Now, its time to utilize much better parameterization to explain the physics of the Earths interior in the inverse issue,” she stated.
At the American Geophysical Union Fall conference in December 2021, Bozdag, post-doctoral researcher Ridvan Örsvuran, PhD student Armando Espindola-Carmona and computational seismologist Daniel Peter from KAUST, and collaborators provided the outcomes of their efforts to carry out international full waveform inversion to model attenuation– a measure of the loss of energy as seismic waves propagate within the Earth– and azimuthal anisotropy– including the way wave speeds differ as a function of proliferation direction azimuthally in addition to radial anisotropy considered in the first-generation GLAD designs.
” With access to Frontera, publicly available information from all around the world, and the power of our modeling tools, weve started approaching the continental-scale resolution in our international complete wave inversion designs.”– Ebru Bozdag, Colorado School of Mines
They used data from 300 earthquakes to construct the brand-new international complete wave inversion models. “We update these Earth designs such that the distinction from observation and simulated data is decreased iteratively,” she stated. “And we look for to comprehend how our model criteria, elastic and anelastic, trade-off with each other, which is a difficult job.”
The research is supported by a National Science Foundation (NSF) CAREER award, and made it possible for by the Frontera supercomputer at the Texas Advanced Computing Center– the fastest as any university and the 13th fastest overall on the planet– in addition to the Marconi100 system at Cineca, the largest Italian computing center.
” With access to Frontera, publicly readily available data from all around the world, and the power of our modeling tools, weve begun approaching the continental-scale resolution in our global full wave inversion models,” she said.
Bozdag hopes to provide better constraints on the origin of mantle plumes and the water content of the upper mantle. “to properly locate earthquakes and other seismic sources, determine earthquake mechanisms and associate them to plate tectonics much better, you need to have high-resolution crustal and mantle models,” she stated.
From the Deepest Oceans to Outer Space
Bozdags work isnt just relevant in the world. She also shares her knowledge in numerical simulations with the NASAs InSight objective as part of the science group to design the interior of Mars.
Initial details of the Martian crust, constrained by seismic information for the very first time, were released in Science in September 2021. Bozdag, together with the InSight group, is continuing to evaluate the marsquake information and deal with details of the planets interior from the crust to the core with the assistance of 3D wave simulations performed on Frontera.
The Mars work put in perspective the scarcity of data in some parts of the Earth, particularly underneath oceans. “We now have information from other planets, but it is still challenging to have high-resolution images beneath the oceans due to absence of instruments,” Bozdag stated.
To address that, she is working on integrating data from emerging instruments into her designs as part of her NSF CAREER award, such as those from drifting acoustic robots understood as MERMAIDs (Mobile Earthquake Recording in Marine Areas by Independent Divers). These self-governing submarines can record seismic activity within the ocean and increase to the surface to provide that information to researchers.
Seismic Community Access
In September 2021, Bozdag became part of a team granted a $3.2 million NSF award to develop a computational platform for the seismology community, known as SCOPED (Seismic COmputational Platform for Empowering Discovery), in partnership with Carl Tape (University of Alaska-Fairbanks), Marine Denolle (University of Washington), Felix Waldhauser (Columbia University), and Ian Wang (TACC).
” The SCOPED job will develop a computing platform, supported by Frontera, that provides data, calculation, and services to the seismological neighborhood to promote education, development, and discovery,” said Wang, TACC research associate and co-principal investigator on the project. “TACC will be focusing on establishing the core cyberinfrastructure that serves both calculate- and data-intensive research, consisting of seismic imaging, waveform modeling, ambient sound seismology, and accuracy seismic tracking.”
Another community-oriented job from Bozdags group is PhD student Caio Ciardellis recently launched SphGLLTools: a visualization toolbox for large seismic design files. The tool kit based facilitates easy sharing and outlining of global adjoint tomography designs with the neighborhood. The team described the tool kit in Computers & & Geosciences in February 2022.
” We supply a complete set of computational tools to envision our global adjoint models,” Bozdag said. “Someone can take our designs based upon HPC simulations and convert them into a format to make it possible to visualize them on computers and utilize collaborative note pads to understand each step.”
Said Robin Reichlin, Director of the Geophysics Program at NSF: “With brand-new, improved full-waveform models; tools to decrease the bar for neighborhood information access and analysis; and a supercomputing-powered platform to allow seismologists to discover the secrets of the Earths and other planetary deep interior, Bozdag is pressing the field into more exact, and open, territory.”
Azimuthal anisotropy (black dashed lines showing the fast direction of wave speeds) in the mantle at 200 km depth outlined on top of vertically polarized shear wave speed perturbations (dVsv) after 20 models based on global azimuthally anisotropic adjoint tomography. To enhance the resolution of present seismic tomographic models, seismologists need to take into account the full intricacy of wave proliferation utilizing mathematical simulations, understood as full-waveform inversion, says Ebru Bozdag, assistant teacher in the Geophysics Department at the Colorado School of Mines.
Bozdag was the lead author of the very first full-waveform inversion model, GLAD-M15 in 2016, based on full 3D wave simulations and 3D information level of sensitivities at the worldwide scale. The model utilized the open-source 3D global wave propagation solver SPECFEM3D_GLOBE (freely readily available from Computational Infrastructure for Geodynamics) and was produced in partnership with scientists from Princeton University, University of Marseille, King Abdullah University of Science and Technology (KAUST), and Oak Ridge National Laboratory (ORNL). They used information from 300 earthquakes to construct the new global complete wave inversion designs.
