The activity of Parícutin varied greatly during the period April 12 to May 3. The strong eruptive activity that began in mid-March, marked on March 17 by the formation of a new boca with a short-lived volcancito and by external changes in the form of the cone, continued until April 18, The period April 12-18 was marked by bomb-showers and explosive blasts at the rate of ten to 15 a minute, mostly from the south vent of the double crater. Most of the bombs fell into the north crater and on the north flank of the cone. From April 19 to 26 the activity was, in general, very weak, and little ash and few bombs were projected beyond the rim of the cone, Explosions were very rare, and the weak vapor column from the Volcano was accompanied by a dull surf-like roar. Most of the vapor emerged from a small vent near the center of the divide between the two coalescing craters. A heavy ash column, at times approaching in intensity that of 1943, emerged from the Volcano from April 27 to 29. The ash was erupted from both the north and south vents of the crater, though the south vent is believed to have contributed the most. From April 30 to May 3 the activity was again very weak, and only a feeble column rose above the cone.