Aotearoa Summary Updated. 27 July 2025 - 11 August 2025
Local quakes have rattled on for days following the massive Pacific Mag 8 period. Seismic swarms and quakes along the Volcanic Plateau have matched the global volcanic period which followed the quake period. Major quakes north and south of New Zealand on 29 and 30 July were always a concern for a quake migration into Fiordland or the North Island. Mag 6 risk for Fiordland reflected this possibility. The South of Fiji 6.6, 5.8 opened the possibility of a quake migration along the Kermadec Ridge into New Zealand with clear results at Ahaura River and Tokaanu. A small quake migration was observed along the Alpine Fault during the period with Mag 2 quakes at Toaroha River (near Cedar Flats hotpool), Upper Arahura River and Mag 4.1, 3.8 quakes at Upper Ahaura River. Equally the forecasters wondered if more action could occur along the Volcanic Plateau as minor quakes and swarms evolved. Volcanic tremor at Ruapehu remains steady but local volcanologists had reported seismic swarms and sulphur degassing earlier in July. The crater lake they say is cold 12C and beginning on a new months long heating cycle, the vent unblocked by lava debris. Solar wind from Coronal Hole 1306 was the driving force for the period and has returned on 11 August, renamed CH1310 with brief Kp6 geomagnetic conditions returning to steady mild Kp4 substorm conditions today and perfect slow buildup to more quakes. A forecast is being processed. 27 July. Nelson 4.0 7.11pm 28 Jul 100km North of White Island 4.0 2.00am Ruatoria 4.6 1.07pm (40km Southeast of Ruatoria 4.8 USGS) 29 July. 300km South of Macquarie Island 6.9 10.10am +series. 30 July. South of Fiji/Louisville 5.8 5.46am 550km depth South of Fiji/Louisville 6.6 5.53am 550km depth Upper Ahaura River 4.1 5.57am Tokaanu 4.2 7.27pm (4.9 USGS) 2 August. Rotorua Mag 2 swarm 12.00pm-1.17pm 3 August. Upper Ahaura River 3.8 12.12pm 4 August. 15km West of Castlepoint 4.1 12.14am 15km West of Castlepoint 4.2 12.22am 5 August. 25km North of Whakatane 4.7 4.56pm Ruapehu seismic tremor 22-11 August. Summary. 30 July 12.00am Local Mag 6 never happened during the period although the Pacific forecast was chasing Mag 6 further south and the possibility that big action could spread into Fiordland. A local Mag 4 quake cluster arrived late on 27 July with some good risk location success at Ruatoria. The forecast only covered the final few days of a period beginning way back on 11 July and the arrival of fast solar wind from Coronal Hole 1306. No forecast was offered for the initial 16 days. Forecast uncertainties with the arrival of spaceweather on 15 July delayed a quake forecast, followed by a long period when the service was offline. The period turned into a Pacific twin Mag 7 and a Mag 6.9 quake period as conditions shifted away from volcanos in June and early July to quakes from mid July. Frustratingly a detailed forecast couldn't be posted until 27 July and the period nearly ended. A Facebook post on 13 July gave some casual spaceweather and quake location clues. Macquarie Island has become a good forecast location success over the wider period. Macquarie Island quakes are much less frequent than Kermadecs quakes because quakes are always more frequent nearer the Equator, less frequent at the Poles. Regardless of lower quake frequency, Mag 8 has been recorded at Macquarie Island in the past and the period was the first since this service began in 2012 where Macquarie Island quakes were frequent enough to make a detailed quake migration pattern study. The period has probably ended on 29 July as 18 days of fast solar wind finally drops to background levels of 400km/second. A separate summary will be posted for the earlier 11-26 July period. The 27-28 July forecast period came from a weak filament eruption arriving at ACE satellite on cue. Magnetic flux density remained positive until 28 July 1200UTC when it suddenly switched to -5nTesla and Mag 6 followed about 6 hours later under mild Kp4 geomagnetic driving conditions. 27 July. Nelson 4.0 7.11pm 28 July. 100km North of White Island 4.0 2.00am Ruatoria 4.6 1.07pm (40km Southeast of Ruatoria 4.8 USGS) Forecast. 27-28 July 2025. Magnitude 6 risk locations are Northwest of Snares Islands, Offshore Doubtful Sound, Offshore Charles Sound, Offshore George Sound. Magnitude 5 risk locations are Puysegur Point, Doubtful Sound, Northwest Arm Te Anau, Offshore Milford Sound, Pyke River, Cascade River, Lower Arawhata River, Haast, Paringa. Magnitude 4 risk locations are Mahitahi River, Copeland River, Toaroha River, Cape Campbell, Masterton, Offshore Kapiti, Dannevirke, Waipukurau, South of Hastings, Tokomaru Bay. Volcanos quiet. A long lasting coronal hole windstream has been blowing since 11 July and still 500km/second. A major Pacific Mag 7 quake period has evolved from these conditions. No forecast was offered during the early part of the period for various reasons. The 13 July Facebook post offered South of New Zealand as an area of interest during the period. Mag 6 quakes are underway in the Macquarie Island region from late 25 July. More Mag 6/7 quakes are possible in the Macquarie Island region and Mag 6 further north extending to Fiordland. Aotearoa Earthquake and Volcano Forecast Service © 2013 - 2025 |
