There are two types of body waves: compressional (P) waves and shear (S) waves. Primary waves (P-waves) travel the fastest, so they arrive at the recording station (seismograph) first. Secondary or shear waves (S-waves) travel slower than P-waves so they arrive second.
Modified frequency modulation (MFM) is an encoding scheme used by PC floppy disk drives and older hard drives.
Meaning: 300 to 3000 kilohertz. Classified under: Nouns denoting attributes of people and objects. Synonyms: medium frequency; MF. Hypernyms (MF is a kind of...): radio frequency (an electromagnetic wave frequency between audio and infrared) Holonyms (MF is a part of...): electromagnetic spectrum (the entire frequency range of electromagnetic waves)