The magnitude M = 7.4 earthquake of April 22, 1991 occurred in a comparatively lightly inhabited region of Costa Rica. Despite dramatic geomorphological effects, including extensive landslides in the mountainous epicentral region, and uplift of the East Coastline by up to 1.5m, structural damage was comparatively light. A number of warehouses, and reinforced concrete buildings in or near the Port of Lim6n collapsed or were badly damaged, and a considerable number of houses supported on tall wooden piles failed. Of greatest interest was the failure of a number of modem highway bridges, due primarily to liquefaction of foundations, or excessive movement of soft soil layers in embankments.