Earth changes in and around New Zealand
What I have noticed about lamestream media is they will produce GENERALISED articles to scare the bejeezus out of people but when it comes to specific threats they will downplay it
New island has formed and continues to grow as Home Reef underwater volcano erupts in Tonga
In the southwest Pacific Ocean, a seafloor ridge that stretches from New Zealand to Tonga has the highest density of underwater volcanoes in the world. On September 10, 2022, one of them awoke. In the days since, the Home Reef seamount in the Central Tonga Islands has repeatedly oozed lava, ejected plumes of steam and ash, and discolored the surrounding water.
Eleven hours after the eruption began, a new island rose above the water surface. The Operational Land Imager-2 (OLI-2) on Landsat 9 captured this natural-color view of the young island on September 14, 2022, as plumes of discolored water circulated nearby. Previous research suggests that these plumes of superheated, acidic seawater contain particulate matter, volcanic rock fragments, and sulfur.
On September 14, researchers with Tonga Geological Services estimated the area of the island to be 4,000 square meters (1 acre) and the elevation to be 10 meters (33 feet) above sea level. By September 20, the island had grown to cover 24,000 square meters (6 acres). The new island is located southwest of Late Island, northeast of Hunga Tonga-Hunga Ha‘apai, and northwest of Mo‘unga‘one.
And the new island continues to grow:
Home Reef sits within the Tonga-Kermadec subduction zone, an area where three tectonic plates are colliding at the fastest converging boundary in the world. The Pacific Plate here is sinking beneath two other small plates, yielding one of Earth’s deepest trenches and most active volcanic arcs.
Islands created by submarine volcanoes are often short-lived, though they occasionally persist for years. Home Reef has had four recorded periods of eruptions, including events in 1852 and 1857. Small islands temporarily formed after both events, and eruptions in 1984 and 2006 produced ephemeral islands with cliffs that were 50 to 70 meters high. An island created by a 12-day eruption from nearby Late‘iki Volcano in 2020 washed away after two months, while an earlier island created in 1995 by the same volcano remained for 25 years.
“The volcano poses low risks to the aviation community and the residents of Vava‘u and Ha‘apai,” the Tonga Geological Service said in an update issued on September 20. “All mariners are, however, advised to sail beyond 4 kilometers away from Home Reef until further notice.” The service noted that most ash should fall within a few kilometers of the vent. [EOS]
This how Radio NZ reports on it.
Volcanic Tongan island keeps on growing
The island created by a volcanic eruption in Tonga continues to grow.
A volcano on Home Reef, between the Ha’apai and Vaav’u island groups, has continued to erupt over the past two weeks.
The area of the reef above the surface continues to grow and RNZ Pacific’s correspondent in Nuku’alofa reports that it now covers an area of eight acres, up from one acre earlier in the month.
But Kalafi Moala reports that officials say there is still no wider threat to the country.
“The geologists here in Tonga have cautioned air flights going into the area, definitely marine travel close to the area, but they say that now at least there is no real threat to the residents of the communities of Ha’apai and Vava’u.
“It is located between those two islands.”
Three people were killed and hundreds of homes were destroyed after a tsunami was generated by the massive January 15 eruption. All resorts on the western side of Tongatapu were completely wiped out.
The Hunga Tonga-Hunga Ha’apai volcanic eruption generated the second largest sound ever recorded since Indonesia’s Krakatoa eruption in 1883. It also produced the largest atmospheric explosion ever recorded.
Experts say the likelihood of another violent eruption happening anytime soon is quite low
In a statement, geological agency GeoNet said it had detected almost 700 small earthquakes below Lake Taupo, the caldera created by the giant volcano, and had raised the volcanic alert level to 1 — minor volcanic unrest — from 0.
The volcanic alert system is based on six escalating levels, but GeoNet notes that eruptions may occur at any level, and levels may not move in sequence as activity can change rapidly.
The Taupo volcano spewed more than 100 cubic kilometres of material into the atmosphere when it last erupted around 200 AD, devastating a large area of New Zealand’s central North Island in a period before human habitation.
GeoNet says the eruption was the largest on the planet in the past 5,000 years.
The agency added while it was the first time it had raised the Taupo Volcano alert level to 1, it was not the first time there had been activity, and said the chance of an eruption remained very low.
“The earthquakes and deformation could continue for the coming weeks or months,” it said.
As reported on the GeoNet website:
There has been an increase in earthquakes and deformation (ground movement) at Taupō since May 2022 indicating volcanic unrest is occurring. The Volcanic Alert Level (VAL) change this week has been informed by our ongoing analysis of monitoring data, increased knowledge of Taupō Volcano from research programmes and new knowledge of causes of past unrest at Taupō Volcano.
Although this is the first time we have raised the VAL to 1, this is not the first volcanic unrest at Taupō. There have been 17 previous episodes of unrest over the past 150 years. Several of these were more severe than what we are currently observing at Taupō. None of these episodes, or the many other episodes which would have occurred over the past 1800 years before written records were kept, ended in an eruption. The last eruption at Taupō volcano was in 232 AD ± 10 years. The chance of an eruption at Taupō remains very low in any one year.
The earthquakes and deformation could continue for the coming weeks or months. While some of the earthquakes may be felt in areas around Lake Taupō, the deformation is currently only detectable by our sensitive monitoring instruments. GNS Science continues to actively monitor the volcano.
The earthquake sequence beneath the central part of Lake Taupō has continued. We have now located almost 700 earthquakes, mainly at a depth of 4 to 13 km beneath the lake (Figure 1).
The earthquake locations in this year’s sequence are forming two clusters in the central part of the lake. There is a cluster beneath the central and eastern part of the lake and a smaller, western cluster centred just offshore from Karangahape.
Shown in Figure 2 is the number of earthquakes detected and located each year since 2000 in the dashed area outlined in the map (Figure 1).
In addition to seismic activity, GeoNet continuously monitors ground deformation (land movement) about Lake Taupō. Our GNSS (GPS) instruments around the lake have observed uplift at a rate of 60 ± 20 mm per year since May 2022 at a site at Horomatangi Reef in the lake. Modelling of the GNSS data indicates that the area that is rising beneath the lake is in the same place as the main region of earthquake activity. This is also where we interpret the existing magmatic system to be located.
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We interpret the ground uplift and earthquake activity to be caused by the movement of magma and the hydrothermal fluids inside the volcano. We have also sampled springs and gas vents around the lake for changes in chemistry that may be related to the earthquake and ground uplift.
Volcanic unrest is when magma or magma-heated hot water and steam forces its way through the ground beneath a volcano, producing earthquakes, ground movement and changes in hydrothermal systems. There have been 17 previous episodes of unrest over the past 150 years at Taupō Volcano (Figure 3).
Episodes of unrest are common at calderas around the world. Volcanic unrest at volcanoes like Taupō could continue for months or years and not result in an eruption.
If there was increased unrest, then we would see more substantial impacts on the local area like:
- Earthquakes with ground shaking and potentially landslides on steep cliffs, especially after rain.
- Liquefaction can occur in the event of larger earthquakes.
- Substantially higher levels of ground deformation, 10s of centimeters or meters, would only occur at higher unrest levels, but could have impacts such as damaging underground services.
- Changes in geothermal activity may also occur with stronger, evolving unrest. This could be beneath the lake or at established geothermal areas in the Taupō area.
The Volcanic Alert Level reflects the current level of volcanic unrest or activity and is not a forecast of future activity. While Volcano Alert Level 1 is mostly associated with environmental hazards, potential for eruption hazards also exists.
New Zealand straddles the boundary between the Pacific and Australian tectonic plates and experiences significant volcanism and earthquakes.
In 2019, White Island, as known as Whakaari, suddenly erupted, spewing steam and ash, killing 22 people and seriously injuring 25 others, mostly tourists. [Geonet, ABC]
From Australian media
Scientists raise alert level for first time after 700 earthquakes detected in New Zealand
A volcano responsible for the biggest eruption to rock earth in the last 70,000 years is just 2400km away. And scientists have just raised its alert level.
It was responsible for the biggest eruption on earth in the last 5000 years – and now, New Zealand’s Taupo “supervolcano” is again showing increased signs of “volcanic unrest”.
The Volcanic Alert Level for the volcano – located just 2400km from Tasmania – was raised to Volcanic Alert Level 1 for the first time yesterday, making headlines across the globe.
The alert sparked fears of a potential eruption within a nation still scarred from the devastating White Island eruption in 2019, which killed 22 people and left 25 with horrific injuries.
Adding to the anxiety is the fact that when Taupo last blew in around the year 232AD, it was the biggest eruption on earth in the last 5000 years, while an even bigger supereruption 26,000 years ago was the most powerful eruption to rock the earth in the last 70,000 years.
But just how likely is a major eruption – and what would happen if such a disaster were to unfold?
What’s happening?
The alert level was raised after 700 earthquakes were recorded in the area since May, indicating “volcanic unrest is occurring”.
While most of those were too small to feel, the largest was a 4.5-magnitude quake.
According to GeoNet, which supplies geological hazard information for New Zealand, volcanic unrest is “when magma or magma-heated hot water and steam forces its way through the ground beneath a volcano, producing earthquakes, ground movement and changes in hydrothermal systems”.
It noted that there have been 17 previous episodes of unrest over the past 150 years at Taupō volcano, and “the earthquakes and deformation could continue for the coming weeks or months”.
The volcanic alert level has been raised at Lake Taupo in New Zealand. Picture: Barekiwi/Destination Great Lake Taupo
Should we be worried?
In a word, no.
GeoNet states that the chance of an eruption at Taupo “remains very low in any one year”, even in the face of increased activity.
Volcanologist Rebecca Carey from the University of Tasmania told news.com.au there was no need to panic at the moment.
“Taupo volcano is a volcano that’s quite active, and it’s what we call a caldera volcano – it goes through phases of small eruptions that are followed by large eruptions on timescales of tens of thousands of years, and some of the repose periods between those events can be thousands to tens of thousands of years,” she said.
“It had been at alert level zero, but because it’s a volcano, there’s magma underneath, and as magma moves around magma reservoirs, and also through the earth’s crust, it cracks surrounding rocks.
“The alert level has been increased to one, which just represents slightly elevated levels of earthquakes due to that rock cracking process as magma moves around.”
She stressed that there were no other signs of unrest, such as elevated temperature levels in the lake as well as volcanic gases, which could indicate an eruption is brewing.
Earthquakes located by GeoNet in the Lake Taupō area from January 1 to September 18, 2022. Picture: GeoNet
“Larger eruptions only happen every hundred thousand years or so, and the last really violent one was only 2000 years ago, so in terms of what we’d be expecting from Taupo in the next 10,000 years or so, we’d expect more smaller-volume, low intensity eruptions rather than another caldera supereruption,” Dr Carey added.
“We can’t be absolutely sure, because magma is produced at different rates, depending on how plates are moving in the earth’s crust, but in order to erupt with a really high volume of magma, supervolcano eruptions need really long storage times for magma generated in the crust.
“New Zealand has some of the best-monitored volcanoes globally, and this change in alert level is probably triggering more monitoring approaches, for example, site surveys, temperature surveys and gas surveys. But the alert level has not been heightened to a level that would trigger anything more than that.”
Memories of White Bay tragedy
While the White Bay tragedy is still fresh in the minds of New Zealanders, Dr Carey stressed that White Island and Taupo were two very different volcanoes with radically different behavioural patterns.
“With White Island, it’s very common to get explosions with very little warning, but with caldera volcanoes (like Taupo), because of the amount of magma stored at depth, we would expect to see a range of heightened indicators before an eruption,” she said.
Tongariro National Park, in the Taupo volcanic zone. Picture: Getty Images
“They are completely different so we shouldn’t expect the same styles of activities.”
What would a supereruption look like?
Dr Carey said “big, violent” supereruptions like the one from Taupo 26,000 years ago needed timescales of “hundreds of thousands of years” to form.
She said that if and when a supereruption at Taupo did occur, Australia would likely be impacted by plumes of ash travelling across the ocean, which could see planes grounded.
Sadly, in New Zealand it would be a completely different story, with most of the North Island “blanketed in ash” and causing significant economic and social impacts, although there would likely be enough warning to evacuate nearby residents as the alert level rose.
“The important message is that this is very characteristic for Taupo – it has happened in the past, most recently in 2018,” she said.
“At this point in time, monitoring systems are so sophisticated at picking up lots of earthquake events so there’s nothing really alarming about this earthquake unrest.”
She added that a major eruption would not be due for thousands of years, meaning nobody alive today need be concerned about a major Taupo incident.
