6/12/2015 — West Pacific / Tonga struck by M6.3 earthquake — Unrest returns as expected


In a rare twist of events, a magnitude 6.3 earthquake has struck the area Northeast of Fiji, near Tonga.

After a period of relative silence at the far edge of the West Pacific, a 6.3 magnitude earthquake has struck Tonga following a flurry of deep activity.

[Tonga / Vanuatu has been absent any large shallow earthquake activity for several weeks (into a few months)]

6.3m tonga june 12 2015


This earthquake in Tonga is a “near hit” on the earthquake forecast issued for the area.

We were watching near the Soloman Islands (East of Papua New Guinea) for shallow larger mid-6.0M activity.   Now a shallow M6.3 has indeed struck East of Papua New Guinea, however, it occurred in Tonga, not the Soloman Islands.

This is close enough to be considered a regional forecast hit in the time frame named, with the magnitude expected.

area named vs. area hit


Why was this mid-6.0M earthquake expected to occur in the Central West Pacific this week?

See the earthquake forecast from 2 days ago, calling for the shallow movement to occur here:


Information on this 6.3 magnitude from the USGS:

Magnitude / uncertainty 6.3 mwp± 0.0
Location / uncertainty 15.595°S 172.997°W± 7.6 km
Depth / uncertainty 28.6 km± 4.9
Origin Time
Number of Stations
Number of Phases 102
Minimum Distance 228.09 km (2.05°)
Travel Time Residual 1.28 sec
Azimuthal Gap 23°
FE Region Samoa Islands region (169)