Aotearoa Summary. 1 September 2020 - 9 September 2020
Mag 6 quakes in Indian, Pacific, Atlantic Oceans, several Mag 5.8/5.9 quakes and some big local action. Volcanos by contrast were subdued as the energy switched from volcanos to quakes. Spaceweather arrived a day earlier than expected, the 29 August 2.47am East of Whangamata 5.6 arriving before a forecast was offered. Regardless, a local forecast was offered for the rest of the period. The East of Whangamata sequence rattled on for several days, the location at the end of the Kermadec Ridge guaranteed plenty of energy. Typically for a long period, global quakes came early in the period, went quiet for a few days and arrived again late in the period. New Zealand was busy early in the period but quakes then slowly faded away as tectonic action retreated towards the Equator late in the period and away from New Zealand. The Lake Rotoroa 5.7 was on Full Moon, generating some online discussion. Lunar modulation was mild, the Moon was near apogee. Southern Kahurangi was offered as the only Lower North Island/Upper South Island risk location, two quakes came in nearby locations. No Pacific forecast was offered during the period apart from a casual outlook for Shetland Islands, Kermadecs quakes which bore some results although at Mag 5. Spaceweather is likely to remain quiet for several days. 29 August. East of Whangamata 4.7 8.29pm EMSC. (4.6 Geonet) East of Whangamata 4.1 10.43pm EMSC. (4.0 Geonet) 30 August. East of Whangamata 4.9 12.45am EMSC. (4.7 Geonet) 30 August. East of Whangamata 4.0 3.32pm EMSC East of Whangamata 4.2 6.10pm EMSC East of Whangamata 4.0 10.46pm EMSC 31 August. East of Whangamata 5.1 1.26am EMSC East of Whangamata 4.1 1.29am EMSC East of Whangamata 4.2 3.38am EMSC East of Whangamata 4.0 3.44am EMSC South of Wakefield 4.0 4.50pm Geonet East of Whangamata 4.0 4.50pm EMSC 3 September. South of Kermadecs 4.9 5.05am East of Whangamata 4.4 7.45am East of Whangamata 4.3 7.46am East of Whangamata 4.3 7.49am East of Lake Rotoroa 5.7 10.13pm Geonet. (5.2 EMSC, 4.7 USGS) South of Kermadecs 5.4 10.39pm 6 September. Rotorua 4.3 4.40am 7 September. East of Whangamata 4.4 3.21pm 9 September. North of East Cape 4.3 2.57am East of Whangamata 4.1 12.21pm Update. 6 September 12.00pm 3 September. South of Kermadecs 4.9 5.05am East of Whangamata 4.4 7.45am East of Whangamata 4.3 7.46am East of Whangamata 4.3 7.49am East of Lake Rotoroa 5.7 10.13pm Geonet. (5.2 EMSC, 4.7 USGS) South of Kermadecs 5.4 10.39pm 6 September. Rotorua 4.3 4.40am The quake period has probably ended on 6 September although some residual spaceweather remains from a long lasting solar wind stream. Very late action, if any, seems more likely in Fiordland, Haast. The forecast wasn't extended after 2 September, a forecasting mistake. Regardless, quakes have continued in or near risk locations, reinforcing the trend that quakes after a forecast period ends or is dropped are more likely in those locations. Excluding nearly all lower North Island and upper South Island risk locations down to just one, Southern Kahurangi is a forecast gain. Quakes went quiet on 2 September, picking up strongly 3 September with some heavy hits at Lake Rotoroa, South of Kermadecs and a late flurry east of Whangamata. Quakes tend to come right at the onset of a forecast period, then go quiet in the middle of the period, followed by a late burst as the period ends. The forecast period is a good example of this trend, although quakes very early in the period sometimes don't always arrive during Solar Minimum, taking a few days to charge up. The East of Whangamata sequence is likely ended but is the longest Bay of Plenty quake sequence observed at this Service since 2012 at least. The Lake Rotoroa 5.7 was widely felt but widely different magnitudes recorded by the seismologists. USGS posted their observation a day late and very low Mag 4.7 from such a widely felt quake... somebody has probably boobed. Geonet are typically Mag 0.2 higher than the others...Mag 5.7 seems slightly high. The Lake Rotoroa 5.7 came on Full Moon which is always a quake modulator, raising magnitude. Lunar influence may have been present but not strongly...it was apogee (when moon is at a far point in its eccentric orbit). No Pacific forecast was offered for the period apart from a casual outlook made on the 1 September Aotearoa update. South Shetland Islands received a substantial Mag 5.4, 5.3, 5.0, 4.9, 4.9, 4.6 sequence and South of Kermadecs 5.4. The big Pacific quake sequence during the period was the Northern Chile 6.9, 6.2, 6.5 rumble. Update. 1 September 11.00pm Local quakes were under Mag 4 today. East of Whangamata hotspot recorded few quakes. Quakes increased in other North Island locations. Spaceweather has continued steadily today, slightly weakening, geomagnetic storming fading. Chile 6.9, 6.3 and Chagos Archipelago 6.2 marked the onset of quakes and slightly justified Mag 6 risk in New Zealand. Local quakes are likely to become less frequent on 2 September but high magnitude is possible. Possibility Mag 6 East of Whangamata continues. Confidence=low. Possibility Mag 6 Kermadec Islands, South Shetland Islands on 2 September. Update. 1 September 12.00am 30 August. East of Whangamata 4.0 3.32pm EMSC East of Whangamata 4.2 6.10pm EMSC East of Whangamata 4.0 10.46pm EMSC 31 August. East of Whangamata 5.1 1.26am EMSC East of Whangamata 4.1 1.29am EMSC East of Whangamata 4.2 3.38am EMSC East of Whangamata 4.0 3.44am EMSC South of Wakefield 4.0 4.50pm Geonet East of Whangamata 4.0 4.50pm EMSC A long quake sequence on the end of the Kermadec Ridge is underway 100km east of Coromandel Peninsula. The sequence has fallen out of the news but plenty of Aucklanders report feeling the quakes. Mag 5.1 biggest so far apart from the 29 August Mag 5.6 starting the sequence. The sequence has similarities to the 16 August 2013 Seddon 6.5 quake sequence where a Mag 5.7 started the sequence on the Friday morning and the Mag 6.5 came two days later on Sunday afternoon. Big quakes started and ended the Seddon sequence and a big quake may end the East of Whangamata sequence. Spaceweather driving the quakes has remained steady through the period, mild G1 geomagnetic storming underway. Spaceweather is set to continue for another day so Mag 5 quakes may continue. Possibility Mag 6 East of Whangamata. Confidence=low. South of Wakefield 4.0 very close to Southern Kahurangi risk location, the only central New Zealand risk location offered. Tolaga Bay is added to Mag 4 risk locations. Pacific quakes are subdued, eruptions are ongoing at familiar volcanos. Update. 30 August 9.30am 29 August. East of Whangamata 4.7 8.29pm EMSC. (4.6 Geonet) East of Whangamata 4.1 10.43pm EMSC. (4.0 Geonet) 30 August. East of Whangamata 4.9 12.45am EMSC. (4.7 Geonet) A long quake sequence is unfolding in the Bay of Plenty. Sequences tend to be longer nearer to the Kermadec Islands on the Northern Kermadec Ridge. Spaceweather has continued overnight and still has plenty of go today. A second weaker burst of spaceweather may occur today. Bay of Plenty and Volcanic Plateau quakes seem possible. Maketu, Rotorua, Tokoroa are added to Mag 4 risk locations. The forecast period is likely to be extended. No Pacific forecast is offered for the period although quakes and eruptions are likely. Forecast. Magnitude 5 risk location is Offshore Bay of Plenty. Magnitude 4 risk locations are Opotiki, Atiamuri, Taumarunui, Mahia, Dannevirke, Southern Kahurangi, Okuru, Offshore Bligh Sound, Northwest Arm Te Anau. Volcanos quiet. Moderate spaceweather is here as this forecast is posted and is likely to continue today at least. A Pacific forecast will be posted later. Aotearoa Earthquake and Volcano Forecast Service © 2013 - 2024 |
