Complex P-Wave Seismograms from Simple Earthquake Sources

Using simple models of the Earth and earthquake source we investigate theoretically the effects on the complexity of short period P seismograms of: increasing the thickness of a surface layer with low P and S velocities in the source region; increasing the source dimensions so that the body wave pulses radiated from the source last up to a maximum of 3 s; reducing the symmetry of fracture. The results show that although source dimensions and symmetry do influence complexity the main requirement for generating a really complex seismogram with the assumed models is a thick (∼10km) low velocity surface layer.