This study aims to investigate the seismic source characteristics, path attenuation (including geometrical spreading and intrinsic attenuation), and site effects of earthquakes in southwestern Saudi Arabia, with the goal of improving understanding of the region’s crustal structure and seismotectonic processes. The broadband seismic network in southwestern Saudi Arabia, equipped with highly sensitive sensors and extensive station coverage, provides an excellent framework for a comprehensive investigation of seismicity distribution, site response, seismic wave attenuation, and source spectra of earthquakes with local magnitudes ( M L ) ranging from 2.5 to 4.8 recorded between 2000 and 2023. A Spectral Inversion Method (SIM), constrained by a reference site, was applied to decouple site response, attenuation effect, and source characteristics from observed P- and S-wave spectra using iterative least squares analysis. The site responses derived from P- and S-wave spectral inversion reveal strong variability across stations located on contrasting geological settings of the Arabian Platform and Arabian Shield. P-wave amplification is generally higher and peaks at 8–15 Hz, while S-wave amplification and H/V spectral ratio peaks show close agreement, indicating that the H/V method reliably captures the fundamental site resonance controlled by shallow shear wave velocity structure. Frequency-dependent attenuation was quantified using empirical relationships, Q p = 112 ± 1.1 f 1.04 ± 0.03 and Q s = 199 ± 2.9 f 0.98 ± 0.01 , indicating significant frequency dependence and suggesting a seismically active and structurally heterogeneous crust in the southwestern Arabian Shield. The displacement source spectra deviate from the classical ω −2 source model, displaying a steeper high-frequency decay that more closely resembles an ω −3 spectral falloff. advanced source parameters, including seismic moment ( M O ), corner frequency ( f C ), moment magnitude ( M W ), source radius r , and stress drop ( Δ σ ), were estimated from corrected displacement spectra of P- and S-waves over the frequency band 0.8–50 Hz. The seismic moment ranges from 2.12 × 10 11 to 3.7 × 10 14 N.m, source radii from 145.1 to 493.3 m, and corner frequencies from 3 to 10.2 Hz. Stress drop values vary from 0.002 to 1.06 MPa (P-wave) and 0.005–2.54 MPa (S-wave). The
Saleh Qaysi (Wed,) studied this question.