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Date & TimeThe date (year-month-day) and time (hour:minutes:seconds) the earthquake occurred in UTC (Coordinated Universal Time) time.
Latitude, LongitudeCoordinates of the epicenter (projection of the earthquake focus on the surface of the earth). The latitude is the number of degrees north (N) or south (S) of the equator and varies from 0 at the equator to 90 at the poles. The longitude is the number of degrees east (E) or west (W) of the prime meridian which runs through Greenwich, England. The longitude varies from 0 at Greenwich to 180 and the E or W shows the direction from Greenwich. Coordinates are given in the WGS84 reference frame.
MagnitudeMagnitude type and value. Earthquake magnitude is a logarithmic measure of earthquake size. There are many different ways to compute magnitudes. They depend on how the amplitudes of the seismic phases are measured on seismograms and on which type of seismic sensor is used. Moreover each method only works over a limited range of magnitudes. The different magnitude types used here are:
ML : Local magnitude : Based on the amplitudes measured on crustal seismic phases adjusted with a specific attenuation law.
mb : bodywave magnitude : Based on the amplitude measured on P waves
Ms : Surface magnitude : Based on the amplitude of Rayleigh surface waves measured at a period near 20 sec.
Mw : Moment magnitude : Based on the moment of the earthquake, which represent the total energy produced by the earthquake
Md : Duration magnitude : Based on the duration of the shaking measured on the seismogram
Region nameThe region name is called "Flinn-Engdahl +" region. Flinn-Engdahl (FE) regions have been defined in 1974 (Flinn et al., 1974) and revised in 1995 (Young et al.; 1995). The boundaries of these 757 regions are defined at one-degree intervals and therefore differ from irregular political boundaries. An improvement of classical FE regions has been proposed by B. Presgrave from the USGS/NEIC and called FE+ regions, in order to better bit political boundaries. Those 1713 FE+ regions are used by EMSC to better labelled the region where an earthquake occurred.
DepthThe depth in km where the earthquake begins to rupture. When it is not possible to constrain the depth by available seismic data, the location program can set the depth at a fixed value. For example, 2, 5, 10 or 33 km. These values stand for shallow earthquake but are not accurate.
ReferencesYoung, J.B., Presgrave, B.W., Aichele, H., Wiens, D.A. and Flinn, E.A., 1996, The Flinn-Engdahl Regionalisation Scheme: the 1995 revision, Physics of the Earth and Planetary Interiors, v. 96, p. 223-297.
Flinn, E.A., Engdahl, E.R. and Hill, A.R., 1974, Seismic and geographical regionalization, Bulletin of the Seismological Society of America, vol. 64, p. 771-993.
Flinn, E.A., and Engdahl, E.R., 1965, A proposed basis for geographical and seismic regionalization, Reviews of Geophysics, vol. 3, p. 123-149.