Focal Mechanism & Beachball Diagrams

Every earthquake's slip on a fault plane can be reduced to three angles — strike, dip and rake — that fully determine how seismic energy radiates outward as a double-couple source. This simulator builds a real 3D focal sphere, colors it by the sign of the P-wave radiation pattern computed directly from the fault-normal and slip-vector geometry, and traces the resulting nodal planes and P/T stress axes live as you drag the sliders. A movable probe station reports the exact first-motion polarity a seismometer would record at any azimuth, the same raw compressional/dilatational picks that seismologists have used since the early 20th century — and that automated networks now invert in minutes — to read a fault's rupture style straight off the "beachball" pattern.