Zone D
This zone has seen significant activity across its width. The most notable event was probably a magnitude 5.1 event near Bolgart in March 1952. Because of the lack of seismic data from the time, it is not clear if this was an isolated event, or just the largest of a large group of events.
The Wyalkatchem area has seen regular periods of seismicity over the years, particularly on the eastern side. A significant group of events (Largest ML 4.5) occurred near Yelbeni, about 25 km southeast of Wyalkatchem, between July and August, 2024.
A region a little further near, about 25 km NNW of Kellerberrin, was very active between 1997 and 1998. The largest in this group of events was ML 4.6, in March, 1997.