Large plates of PMMA (polymethylmethacrylate) containing a long edge crack were subjected to a tensile fracture. The brittle crack was brought to an abrupt stop at a pre-determined point. A new technique of crack-arrest, which produces a large discontinuity in fracture toughness while introducing only a small discontinuity in the acoustical properties is described. The strain field emitted during the run-arrest event has been measured in detail using conventional strain gage technique. The fractures take place under a state of nearly plane stress. Consistent with the plane strain analysis of Freund, the field becomes static behind the shear (Rayleigh) wavefront at points lying directly ahead (behind, i.e. on crack face) the arrested cract tip. For points not lying on the crack plane, the analysis predicts that the field is always timedependent. It is experimentally shown that in a circular region of radius roughly equal to the run-arrest length, the field becomes static (for all practical purposes) behind the shear wavefront emitted by the arrested tip. A fairly strong discontinuity is propagated with the Rayleigh wave emanating from the arrested tip. Finally, the strain field radiated during the run-arrest event is strongly angle-dependent: loading waves are propagated in a small sector in front of the crack while waves of unloading are propagated in all other directions.