SUBHASH MISHRA
Dhanbad, Sept 4: Prof. Pratap Narayan Sahay, a distinguished professor of geophysics at the Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Mexico, and an alumnus of IIT (ISM) Dhanbad (Batch of 1977), delivered a keynote lecture on “Slow Shear Wave in Poroelasticity” at the institute today.
Scientific Insights into Slow Shear Waves
Speaking at the Conference Hall of IIT (ISM), Prof. Sahay explained the scientific foundations of the slow shear wave in poroelasticity, emphasising its emergence due to fluid viscous stress. He highlighted the contrast with the fast shear wave, which represents in-phase shear motion of solid and fluid phases, noting that the slow shear wave occurs as an out-of-phase motion. He described it as highly dispersive and attenuating within half a wavelength.

Advancing Beyond Biot Theory
Prof. Sahay’s lecture also shed light on the limitations of the Biot theory of poroelastic wave propagation and discussed the advancements brought forward by the de la Cruz–Spanos poroelasticity theory. His insights offered participants a deeper theoretical framework for understanding poroelastic wave behaviour.
Warm Welcome from Faculty
The session was organised by the Department of Applied Geophysics. Prof. Saumen Maiti, Associate Professor and Head of the Department, welcomed the chief guest, while Prof. Partha Pratim Mandal introduced Prof. Sahay to the audience.
Senior Faculty in Attendance
Several senior faculty members attended the programme, including Prof. Sanjit Pal, former Head of the Department; Prof. Saurabh Datta Gupta, Associate Professor and Professor-in-Charge (International Relations & Alumni Affairs); and Prof. Swarndeep Sahoo, Assistant Professor.








