Geophysical Activity in 1990
Karen Goodfellow · The Leading Edge · 1991
This special report comprises worldwide geophysical activity for the year 1990. The data were gathered from survey questionnaires mailed to 460 users of geophysical methods in all parts of the world except the former Soviet-block countries and the Peoples Republic of China. Of those mailed, 206 questionnaires were returned, virtually the same response as 1989 when 209 were returned.