ON December 21, San José (Costa Rica) suffered the most severe earthquake it has known since 1923. Buildings were cracked, including the cathedral, though no casualties are reported. The shock was-recorded at Manila, at De Bilt (Holland), where the P wave arrived at 21h. 7m. 10s. G.M.T., and at Kew where the first of three shocks in rapid succession arrived at 21h. 6m. 51s. G.M.T., the maximum ground amplitude at Kew being 0·42 mm. On December 22, considerable damage is reported to have been caused by earthquake shocks in CostaRica, though no loss of life or other casualties are reported. These shocks were possibly after-shocks of the earthquake which rooked San José on December 21.