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Analysis Study Research Paper | Geology | Libya | Volume 12 Issue 5, May 2023
Surface Wave Dispersion Tomography in Libya
Abdusalam Agail | Anibal Sosa | Aaron A. Velasco | Azucena Zamora | Fathi Ghanem
Abstract: The Mediterranean region has evolved into a geologically complex area due to its geodynamic evolution and its position near the boundary between the Eurasian and African plates. To better determine the Earth structure in Northern Libya and the southern - eastern Mediterranean Sea, we analyze regional seismograms (< 30? from an earthquake) recorded by the Libyan National Seismic Network (LNSN) and compute Rayleigh wave group velocity dispersion curves over periods of 20 - 80 s, individually measuring over 640 waveforms from 67 earthquakes covering the Northern Libya to southern - eastern Mediterranean regions. To process this data, each waveform is: 1) updated with the epicentral parameters, 2) rotated (N - E to R - T), 2) the instrument response removed, and 3) reviewed manually for stability by ensuring that only data with clear surface wave arrivals will be included. The data is then processed for group velocity, and again quality controlled for stability based on visually inspection of each dispersion curve. We then performed a tomographic inversion of Rayleigh group velocities to obtain 2 - D tomographic maps group velocities variations at each period on a grid of 2.0? x 2.0? assuming a constant isotropic velocity model. Although the data are limited and not optimal, we were able to extract reasonable Rayleigh dispersion group velocity curves from the tomographic maps. We present maps that show the region complexity and will be using this data to generate 1 - D shear wave velocity models in a separate study with additional data (specifically receiver functions and gravity measurements).
Keywords: Rayleigh wave, Group velocity, Surface wave tomography, Northern Libya, East central Mediterranean
Edition: Volume 12 Issue 5, May 2023,
Pages: 357 - 360