Each sensor provides the digitiser with an analogue signal that is digitised and retransmitted to IRD in real time. The software that processes the data in real time is SeisComp3. In a nutshell, its role is to :
  • analyse each signal or “trace” in real time, thereby detecting any seismic signals
  • correlate incoming signals from all stations. If a minimum number of stations detect signals in a meaningful timeframe that accounts for the distances to the various stations, a new quake is deemed to have been detected and its main characteristics, ie focus co-ordinates, magnitude, number of stations detecting it, etc, are determined
  • using Seiscomp3, all the region’s stations and their status can also be visualised, including those in the New Caledonian network. An “alert screen” immediately displays the stations that detect the arrival of a seismic wave, with the stations’ symbols flashing, and when an earthquake has actually been detected, it displays its characteristics in real time

Example of Real-Time Earthquake Detection

Signals from stations are detected. The closer the station is to the earthquake, the earlier the signal arrives. The illustration clearly shows all the stations that detected the earthquake, ranging from the nearest to the focus to the furthest :

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At the same time on the control panel, the stations that detected the earthquake are shown by a flashing symbol :

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The earthquake characteristics are then determined in near real time, depending on when the data arrive. In this case it is in approximately 12 minutes. For an earthquake occurring in the region, the time is 4 to 5 minutes :

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