@INPROCEEDINGS{leibel_focus_2022,
    author = { Leibel, Thibaut and Belin, Vivien and Cormier, Adrien and Renat, Zoé and Cupillard, Paul },
     title = { Focus detection in time reversal simulation },
 booktitle = { 2022 {RING} {Meeting} },
      year = { 2022 },
     pages = { 13 },
 publisher = { ASGA },
  abstract = { Time reversal is a technique which enables to locate seismic events with a single numerical backpropagation of seismograms recorded at a set of stations. Seismic stations act as sources and generate a wavefield that converges towards the actual event, producing a focal spot which reveals its position. This method is poorly sensitive to noise, but it needs a close surface of stations around the medium and a good knowledge of the geological setting. Moreover, the detection of the focal spot is not trivial, especially when a lot of earthquakes are involved. In this context, long timeseries are backpropagated, so the time-reversed wavefield represents a huge amount of 4D data to be analyzed. To circumvent the storage of these data, focal spots have to be detected on the fly and/or the amount of simulated data has to be reduced. In this work, we propose and implement a method to achieve this, relying on the symmetry of the backpropagated wavefield with respect to the focus time. The method is applied to a synthetic seismic crisis in which multiple events with various magnitudes occur in a small time interval. }
}