The only magnitude 8.0 or greater earthquake in January-June 1989 happened near the Macquarie Island outside the Test area. It has the following parameters listed in the NEIC PDE: origin time 1989/05/23 10:54, latitude 52.34S, longitude 160.57E, depth 10 km, and M=8.2. This earthquake occurred about 1000 km south of New Zealand on continuation of Macquarie Oceanic Ridge. The epicenter region is characterized by very low rate of seismic activity of only 4.5 events per year in the radius of 667 km. This does not allow us to apply standard version of the M8 algorithm here. However, its modified version (set up for applications in lower rate seismic activity regions) would have distinguished the rise of activity and predicted this earthquake (see Figure "Macquarie 1989").
Macquarie 1989