**8.2. Search for correlations between** *q***-factor alerts and earthquake notifications**

At present, several services distribute online notifications within 2 min of an earthquake that has occurred anywhere in the world, which give latitude, longitude, time, and magnitude of the earthquake, see, for example [21]. Not all subsea earthquakes generate tsunamis. The as‐ sumption here is that any subsea earthquake with magnitude higher than 5 can be consid‐ ered to be the origin of a tsunami. The approximate expected arrival time can be calculated from Eq. (10) using the depth profile between the earthquake origin and the radar near field of interest. A threat window can be set up within ±0.5 h of the predicted arrival time, and any *q*‐factor candidates within this window would be given increased priority.
