GENERAL GEOLOGY

Detailed explanation-1: -Seismographs and accelerometers. Seismographs are used to measure ground motion in both earthquakes and microseisms (small oscillations described below).

Detailed explanation-2: -A seismometer is an instrument that records the shaking of the Earth’s surface caused by seismic waves. The term seismograph usually refers to the combined seismometer and recording device.

Detailed explanation-3: -No. Neither the USGS nor any other scientists have ever predicted a major earthquake. We do not know how, and we do not expect to know how any time in the foreseeable future.

Detailed explanation-4: -Radon emissions Radon is useful as a potential earthquake predictor, because it is radioactive and thus easily detected, and its short half-life (3.8 days) makes radon levels sensitive to short-term fluctuations. A 2009 review found 125 reports of changes in radon emissions prior to 86 earthquakes since 1966.

Detailed explanation-5: -The simplest method of locating an earthquake on a globe is to find the time interval between the P-and S-wave arrivals at several seismograph stations. The distance to the earthquake from each station is then determined from standard travel-time tables and travel-time curves.