Of Quakes, Sulphur, Steam, Deep Holes & Things That Go Bump

There has been much disquiet of late that the quakes around Christchurch may have a volcanic origin, especially as the second set of quakes feel a lot different to the afterquakes following the Sept quake. We did a hunt around and found evidence that these fears are unfounded. This is just a lose collection of data we’ve found on the net for any one who’s interested, or who wants to add something extra.

Out of Akaroa after 6.3 9 March Trade Me Forum

Was talking to a mate at work today ,and his friends (a couple) that have been unsettled by the quake and days following, wanted to get away from their house that is in not to good a state,stayed at selwyn hutts a couple of nights then went to the ladies fathers place in Akaroa,one of the fathers friends that has been a fisherman there for near 30 years , he has come across a new hole in an area he is very familiar with that used to be completely flat ,his depth sounder could not register a depth and there was a smell of sulphur. Anyone else heard of this?

It seemed that nobody had.

Lyttelton volcano revival discounted

“Some people have even expressed fears the extinct Lyttelton volcano might be coming back to life. However, recent Canterbury University geology doctoral student Dr Sam Hampton said there was no evidence of volcanic activity.

The Lyttelton volcanic complex finished erupting 5.8 million years ago. Hampton said he had discovered recent faulting at Allandale, where the road was cracked and the centreline had been offset by one to two centimetres. Also as a result of faulting, outflow from warm springs at the northern end of Rapaki Bay had increased. There were six sulphurous springs of up to 20 degrees Celsius within about 60 metres of the beach and oriented west-east, he said. ‘The distinct sulphurous smell associated with these hot springs and other outflows is due to water coming up from depth, much like Hanmer Springs, and not to do with magma-water interactions'” The Press 11Sept

Underground water shaken up by fault

“Some farmers say their paddocks have never been wetter. ECan acting director of investigations and monitoring, Tim Davie, said the quake could have a lasting impact, with some wells broken. No lasting large-scale changes were expected to aquifers. Sulphurous smells were being reported around the region but it was unlikely they were all related to new springs, he said. ‘My view is it’s some of the peat that’s been exposed to air oxidising‘” + new hotspring at Magazine Bay..”

Twitter

cherylbernstein about the second quake :

These new banging jolts are quite different to the rumbling September shocks, as @Motmunter said. #eqnz

Motmunter:

These aftershocks aren’t like the old September ones which rumbled up and gave you a shake about. These ones just slam into the house #eqnz 8 March

The Star Canterbury

The giant boulder shaken loose by the earthquake left indentations in the hillside then destroyed the house at Rapaki and spilled debris into the front yard. 28 Feb Canty Star

Facebook

Ken ‘Dusty’ Duncan Nov 28 2010

volcano is us joking but in week after the wee shake & night before the 5.1 over lyttleton way we could smell sulphur here in Wigram as could many other people I have spoken too around the city. Geonet first said it was likely rubbish somewhere. but then they wrote an article about lyttleton volcano saying it had not erupted for 5.8 million years so will not erupt. thing is about a month before wee shake a volcano I think it was in Indonesia erupted after not doing anything for over a million years. Papatuanuku does what it wants too. not what man thinks it should.

Kathy Watkins

I did also hear that the people walking up the Rapaki Track could also smell sulphur around the same time !!!!

GeoNet

Yes, there have been reports that springs in the Lyttelton area have warmed up, but this is not a surprise following a large earthquake. After the 4 Sept earthquake, changes in springs and bores were seen all across Canterbury and beyond – even as far as parts of North Island. The shaking opens up small cracks and pores in the sediments beneath the earth’s surface and can let water move around – potentially bringing warm water from depth up through normally cool springs. After 4 September, GNS monitored bores around the country to watch the changes. So although the effects are likely to be most obvious near to the epicentre, they occur over a wide area.

Leigh

Hi Geonet, the 3 calderas in Banks Peninsula are extinct, but is the magma plume still alive and are the sound waves for this being tested. I have read that about the same time the Greendale fault last shifted was also about the same time the caldera at Lyttleton erupted.  I’ve also looked at the pacific plate movement over the millions off years through a number of sites, with the 3 calderas in mind, if the plume is still active then it’s position would be near to directly under Christchurch. At the end of the day my question is.. Are the sound waves being tested under us??

GeoNet

The Banks Peninsula volcanos are long extinct with the last eruptions around 6 or so million years ago. There is no chance of them erupting again as the plate boundary conditions that allowed them to form in the first place no longer exist. 6 Million years is a long time in a volcano sense and volcanism that once existed along the east coast of the south island has long finished. All current and future volcanic activityin NZ will be located in the North Island.

If volcano unrest does occur we see quite different types of earthquakes from what we are seeing now. During volcano unrest we see earthquakes that indicate magma movement which are quite distinct from the tectonic earthquakes we see now.

All the scientific modelling of the data over the last weeks and months shows conclusively that the Canterbury earthquakes are due to fault movement only. There is no volcanic component to them at all. The ground deformation has also been modelled and this shows only fault related movement and nothing to suggest intrusion of magma beneath the Peninsula. Again if this were the case it would produce a quite distinct signatutre much different to what has been recorded.

Any hot springs in the area are also not volcano related, again water that is part of a volcanic system has quite different chemical make up to “non volcanic” hot springs and the 2 can be easily distinguished.

The fact that there are old volcanoes near to where the earthquakes are located is really just coincidence.
<from Craig one of our handy volcano experts>

Leigh

@ Paul thanks @ geonet thank you:) feel at ease with regards to the reply, thank Craig too, explains it nicely and agree with Jonathan.
I herd on the news tonight the fault itself is now sitting low in the magma and could cause another large quake at some point. If this is the case then would it be more concentrated on the actual fault line

An explanation of the mechanics of the February 22 earthquake

A September 2010 earthquake centered 40 kilometers (25 miles) west of Christchurch, in the plains near Darfield, struck at 4:35 a.m., had a magnitude of 7.1, and caused some structural damage and one death (by heart attack). The earthquake in February 2011 occurred at 12:51 p.m. and just 10 kilometers (6 miles) from the center of Christchurch. It had a magnitude of 6.3, though was officially classified—scientifically speaking—as an aftershock of the 2010 quake. At least 166 people died, and the city of Christchurch was devastated structurally and emotionally. Many people are still missing.

The natural-color image above was captured on March 4, 2011, by the Advanced Land Imager (ALI) on NASA’s Earth Observing-1 (EO-1) satellite. Overlain on the map are seismological measurements of the ground shaking in the Christchurch area on February 22, as noted by the U.S. Geological Survey’s Earthquake Hazard Program.

The deeper the red color of the circle, the more intense the “peak ground acceleration,” or shaking of the earth. Note how intensity is highest right around the most densely developed areas of Christchurch. City officials and news accounts also described liquefaction—the softening and loosening of the soil due to shaking and groundwater penetration—that was 300 to 500 percent worse than during the September 2010 earthquake.

There are two forms of energy that cause the shaking in an earthquake. “P” or primary waves provide the initial, often vertical, jolt that lifts people and structures off the ground. “S” or secondary waves lead to horizontal shaking. Most structures collapse during the longer-duration S waves because buildings are not designed to handle this side-to-side motion. In Christchurch, the quake occurred so close by that the lag between P and S waves was a mere second.

  1. References

  2. GeoNet (2011, March 4) Christchurch badly damaged by magnitude 6.3 earthquake. Accessed March 8, 2011.
  3. GNS Science (2011, February 25) February 22nd earthquake in Christchurch. Accessed March 8, 2011.
  4. New Zealand Herald (2011, February ) Christchurch earthquake: Levels of liquefaction 300-500 pc worse. Accessed March 8, 2011.
  5. U.S. Geological Survey (n.d.) Shake Map: South Island of New Zealand. Accessed March 8, 2011.

Epicentre in GeoHack http://toolserver.org/~geohack/geohack.php?pagename=2011_Christchurch_earthquake&params=43.5834_S_172.7012_E_

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