In 1906, the seismologist Richard Dixon Oldham fundamentally altered geophysical paradigms by analyzing the global dispersion of earthquake records to identify a seismic "shadow zone." Within this zone, specific classes of seismic energy—primary (P) and secondary (S) waves—failed to register on seismographs located at particular angular distances from an earthquake's epicenter. The prevailing models of the era posited a relatively homogenous, solid Earth. However, Oldham understood the distinct mechanical properties of these waves: P-waves are compressional and can propagate through both solid and liquid media, whereas S-waves are shear waves that rely on the rigidity of the medium and thus can only travel through solids.
Oldham observed that while P-waves eventually reappeared on seismographs positioned at extreme distances from the epicenter—albeit significantly delayed and refracted—S-waves remained entirely absent beyond an angular distance of approximately 104 degrees. From this stark discrepancy, Oldham deduced not only that the Earth's interior was highly heterogeneous, but specifically that it harbored a distinct central core that was liquid in state. The total attenuation of the S-waves provided the crucial evidentiary basis for this conclusion. Because a fluid medium lacks the shear strength to transmit S-waves, it completely absorbs them, while simultaneously permitting compressional P-waves to pass through, albeit along sharply bent trajectories caused by the severe density differential at the boundary between the solid mantle and the liquid core. It was not until Inge Lehmann's subsequent seismological analyses in 1936 that the presence of an inner solid core within that liquid outer core was identified—a subtle nuance that Oldham's initial macroscopic analysis could not have resolved given the sensitivities of early twentieth-century instrumentation.
Statement: If S-waves were capable of propagating through liquid material, Oldham’s 1906 analysis of the seismic shadow zone would have lacked the necessary evidence to deduce that the Earth's central core was liquid.
Based on the specific details provided in the passage, is this statement logically true or false?
Cevap: Cevap