Warning: Display title "Dictionary:M" overrides earlier display title "Dictionary:M(Mega)".
1. Mega-, SI prefix for 106. 2. Roman symbol for 103, as in MCF of gas. MM is used for 106 in the petroleum industry. 3. The earthquake phase with the maximum amplitude on the seismogram, now obsolete. 4. The ratio of porosity determined from a sonic log to that from a density log.