GNS Science says its seismic equipment is sometimes picking up false earthquakes, known as ghost quakes.
Ghost quakes can occur when a distant earthquake is picked up and identified as several small closer earthquakes.
Waves from a recent Kermadec earthquake were initially identified as two smaller quakes in New Zealand on Geonet's website, and later deleted.
GNS Seismologist Elizabeth Abbot spoke to Ingrid Hipkiss.
