Storm due to whip quake-affected Raglan
Raglan is going through a mini-crisis after the 7.5-magnitude earthquake that was so powerful it was felt by the Large Hadron Collider in Europe.
The coastal town has been on water restrictions since Monday's quake rocked the country with the pumps at the Riki Springs, which feeds the town, shutting down.
There has also been a water pipe burst and road damage needing repair although there is no suggestion the subsequent events were quake-related.
Principal scientist at GNS Science in Dunedin Dr Simon Cox said the effects of a quake on groundwater can occur "thousands of kilometres away" and he is in no doubt Raglan's water could also be affected.
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"Earthquakes send seismic waves all around the place and when they get to some distal place, they can stimulate pressure changes in the aquifers," Cox said.
On Tuesday morning, Otonga Valley Rd collapsed at a culvert, cutting off 15 families. A temporary bridge has been installed to allow light vehicle traffic to cross.
And on Wednesday morning, a water main burst near Greenslade Rd. Dangerous ground conditions prevented staff from repairing the damage immediately and work was ongoing throughout the day.
And now, MetService meteorologist Tom Adams is warning of strong winds of up to 110kmh in exposed areas in Raglan and Kawhia and between 10 and 20 millimetres of rain per hour.
By 11pm, heavy downpours are forecast and will continue through to the early hours of Thursday morning, coinciding with 3.6m high tide at midnight Wednesday.
Cox, a structural geologist, has been studying the effects of earthquakes on aquifers and thermal springs in the Southern Alps. Monitoring already shows water bores in Northland were affected by the 2009 Fiordland quake and the Christchurch quakes.
Two mechanisms can be at play, he said. One is where the underground water source is put under pressure from the quake.
"Essentially it is like squeezing and releasing and squeezing and releasing – it's kind of like squeezing a sponge and letting it in and out and that."
And the other is a high frequency shaking he describes as "sonic cleaning".
"It can knock little fine bits and make the water turbid and also the flow can pick up and change for a period after the earthquake."
Shortly after the Monday shake, sensors at the Riki Springs pumphouse recorded discolouration in the water and automatically shut down.
As the main water source for Raglan's reservoirs, residents have been on a severe shortage since Monday morning with tankers used to top up reservoirs and fill containers
A no wash, no flush and three-day boil notice for drinking water is in place until testing clears the town supply of contaminants.
Essentially, it's liquefaction in the water, Cox said, that will settle down in 24 hours or "a week at worst".
Waikato District Council water technicians were monitoring the water as it was being flushed through the pump station. Shortly after an announcement was made on Tuesday that the pumps would be turned back on, an aftershock occurred in the central North Island and the technicians noticed the water cloud over again.
Cox said he had never heard of people witnessing the quake effect.
"Not actually seeing it during the earthquake or changing in front of your eyes which is kind of cool," he said.