A seismologist is a scientist who does research in seismology. Unsourced material may be challenged and removed. Scholarly interest in earthquakes can be traced back to antiquity. Seismic hazard analysis pdf, set in motion intensified scientific attempts to understand the behaviour and causation of earthquakes.
Michell determined that earthquakes originate within the Earth and were waves of movement caused by “shifting masses of rock miles below the surface. He is also responsible for coining the word “seismology”. P-waves, S-waves and surface waves on seismograms and found the first clear evidence that the Earth has a central core. The development of this theory depended on the considerable progress of earlier independent streams of work on the behaviour of elastic materials and in mathematics. Three lines with frequent vertical excursions.
Seismogram records showing the three components of ground motion. S-waves are slower than P-waves. Therefore, they appear later than P-waves on a seismogram. Fluids cannot support perpendicular motion, so S-waves only travel in solids. Rayleigh waves result from the interaction of vertically polarized P- and S-waves that satisfy the boundary conditions on the surface.
Love waves can exist in the presence of a subsurface layer, and are only formed by horizontally polarized S-waves. Earth’s surface and their energy is thus trapped near the surface, they can be much stronger than body waves, and can be the largest signals on earthquake seismograms. Surface waves are strongly excited when their source is close to the surface, as in a shallow earthquake or a near surface explosion. Earth “ring” like a bell.