Etratum

In the report "Eruption of El Chichón volcano, Chiapas, Mexico, 28 March to 7 April 1982" by J. M. Hoffer et al. (24 Dec., p. 1307), the millimeter readings in figure 2 (p. 1308) were in error by a magnitude of one; the 100, 200, 300, 400, and 500 mm contours should have been 10, 20, 30, 40, and 50 mm.