Another 6 small earthquakes in the last 4 days including 2 this morning, has now bought the gulf earthquake swarm count to a milestone of 100 quakes since commencing on 26 December 2018. The increased activity since last Friday comes after silent phase of 82 days when no earthquakes were recorded by GeoNet seismic drums.
Latest 6 quakes
M 2.2 31 July
M 2.7 2 August
M 2.5 3 August
M 2.9 3 August
M 2.5 4 August
M 2.4 4 August
Image: GeoNet Google earth
The largest quake in the swarm sequence over the last 18 months was a magnitude 4.1 on 10th February 2019. For comparison, Northland and Hauraki Gulf region in the 12 months prior to the swarm’s commencement, had a total number of 5 earthquakes. The next closet sized swarm in the Hauraki Gulf occurred in 2007 with 13 shallow earthquakes over a 4 month period.
Here is the date and magnitude plot of the swarm up until 2pm, 4th August, 2020.
The swarm is also in the same location as the Niagara shipwreck. The Niagara was sunk on 19 June 1940 by a German marine mine and is still believed to be carrying up to 1000 to 1500 tonnes of oil.
For reference, GeoNet’s official statement on the earthquake swarm released on 10 February 2019 when the count stood at 39 quakes. https://www.geonet.org.nz/news/2esDFOtQyOAh8yaYFp2Pt4