A head wave refracts at an interface, travelling together it, throughout the decreased medium and makes oscillatory motion parallel towards the interface. This motion brings about a disturbance inside the upper medium that may be detected on the surface area.[9] The exact same phenomenon is utilised in seismic refraction. Returns http://multipletimereferences42851.thezenweb.com/Not-known-Facts-About-Date-and-Time-Shift-Testing-11218896