Out in the Field - Tagging along with the boys

Yesterday i went along with two of our technicians, Sam and Todd, they were out and about to fix some of our equipment out in the field.  Maintenance is an important job, as we have hundreds of stations all over New Zealand and we have to keep them up and running, weather, computers and animals can all cause issues.

Lack of a view

First stop was up Mt Climie which on a fine day allows you to look over the Hutt Valley over Wellington the the South Island. Yesterday, however, it was very cloudy and windy so not much of a view!

Mt Climie is a repeater site for all of our Wairarapa stations a major comms hub for all of our Wellington stations and an important backup link, so when something isn't working we have to get up there right away and get it fixed! It didn't take Sam long to get it back up and running though.

Lucky the equipment is in a nice cosy concrete tank.

Sam fixing the radio

Todd and i looked helpful

Next stop was Moutere Hill in Levin, this is one of our cGPS sites, its on top of a hill in a farmers paddock. The boys put in a new lightning arrestor, this protects our equipment against surges and lightning, this one had gotten wet so was shorting - not very helpful, they think it was due to condensation in the cabinet.

View towards Levin

Todd and Sam hard at work

Locals on the way out.

GeoNet HQ : bells, whistles and flashing lights?

Now in exciting disaster movies when they show the experts and scientists, their offices look really exciting with flashing lights and all sorts of moving gadgets.

A few years ago i posted a wee video tour of our offices, we have had a few inquiries recently on what its like here at GeoNet HQ, so i thought i would make a brand new video.

So you can have a behind the scenes look at our offices,  unfortunately its not quite as exciting as the movies, unless there is a big event and then its all go!

So here it is:

To the beach, for work, honest!!!

Last week i went to Castlepoint beach with technician Sam, this beach is one of my favorites and i have some great childhood memories here, i also spent my birthday here and blogged about the beach / holidays and tsunami risk in April.

On this day though we were here to fix the cGPS (continous GPS), so we turned away from the beach and went up onto Castlepoint Station farm.

After a bumpy ride we were up on top of a hill, with a great view, at the site. This site 'CAST' is a combined cGPS and seismic site, so we get earthquake information as well as ground deformation information.

We had stopped receiving data from the GPS part of this site, and our monitoring system 'Big Brother' told Sam it was due to a broken Net RS.

Old yellow RS and the new Grey R9

 So Sam had brought out a shiny new Net R9 (latest model) to replace it. The Net R9 is a GPS reciever, it gets the data from the GPS and then sends it back to us at GeoNet HQ.  

After swapping the instruments Sam discovered that the site was still not receiving data, so it was investigation time!

Sam investigating

He discovered that water had gotten into the conduit that takes the cable from the cGPS to the receiver, this had then caused a short and killed the Net RS, the water had also caused the lightning arrester to corrode and stop working.

Now usually when our team go and check on sites they take a box of spare bits! Unfortunately, due to unforseen events <read:memory lapse>, this box was still in the lab back at the office!  But being good kiwis we made do and got it back up and running!

So to start with Sam created a drain hole in the conduit and got to removing the water in there -  a really fun job as you can see in the pic below ... 

High-tec water removal method

While i cleaned the lightning arrester with a hairclip!

Sam then replaced the special waterproofing tape on all the joins and everything was back up and running.

This is only a temporary fix to get the data coming back in, so next time one of our technicians are in the area (we have a tsunami gauge out here too) they can replace the cables and pipes, for a more long term fix.

Lightning Arrester

Out in the field : Volcanic gas-drive

 

Today i got to be driver for Agnes Mazot, volcanic Gas Geochemist at GNS in Wairakei, while she completed a volcanic gas-drive for our active Tongariro volcano / Te Maari crater.

For volcano monitoring we measure three gases in total: Sulphur Dioxide (SO₂), Carbon Dioxide (CO₂) and Hydrogen Sulphide (H₂S) we usually do this (for White Island and Ruapehu) by plane or permanent instrument MiniDOAS (you can read about it here). These gases are important as they can tell our scientists what is happening in the volcano.

Today we were looking at SO₂  to get this you need to fly under the plume made by the volcano. However, with Te Maari crater its hard to do this as you can't fly that low due to the terrain, and you would then miss the important part of the plume. So instead our scientists have been loading the equipment up in a corolla and driving beside the volcano and under the plume.

We use a piece of equipment called COSPEC to measure the SO₂ it gets secured in the car with a section sticking out of the window that looks up into the plume where it then measures the absorption of UV light by SO₂

The COSPEC

All strapped in

Interesting view!(it has a mirror attached so it views the sky)

FLYSPEC strapped on

For this trip we also had another piece of equipment called FLYSPEC (this a newer version of the COSPEC) Agnes is testing this before she travels to Vanuatu at the end of the month to teach the local scientists how to use it and then it will be used on Tanna island to help them monitor Mt Yasur volcano. The FLYSPEC is a lot smaller than its older 'big blue' model and got to sit on the roof of the car.

I actually visited this volcano in Feb, you can read about my volcano adventure here.  

After everything was strapped on Agnus turned the instruments on and got her laptop up and  running, data would come through and she could then calibrate the COSPEC and see exactly when we were driving right under the plume. We drove a transect 8 times so we could get good concentration of data, she then goes back to the office and looks at the data we gathered and gets a good idea of whats happening inside Tongariro.

Te Maari crater and its ever present plume

 Although we collect and analyse a lot of data, volcanoes are still a product of nature and can erupt with no warning at all!

Plates and Quakes

We often get people commenting on the earthquakes moving up or down New Zealand and the pattern you can sometimes see, and why we get so many when our neighbors in Australia get so few!  Well the answer is plate tectonics, the earth's outer shell is made up of plates, they are in constant motion and where they interact is where you get earthquakes, mountains and volcanoes. So here in wee New Zealand we are right in the middle of the boundary of two of these plates (this is why we get all of the fun geological hazards) Australia on the other hand are right in the middle of the Australian plate, so only a few quakes for them!

Here is a map showing the last 1500 quakes in NZ of weak intensity and above (you can see these maps and select all of NZ or just a region under the 'Map & Stats' tab on our website).   I've added in (an awesomely drawn) very rough red line that shows the tectonic plate boundary that we live on, and you can see the quakes follow this.   Its very interesting as the two plates interact differently along this boundary.

In the North Island the Pacific plate is going down under the Australian plate (subduction) so that's why the quakes are more spread out, and why you can get deep events in the middle of the North Island such as this 2012 Taupo event  The seismic waves travel very well along the boundary between these two plates and so the earthquakes are often felt very strongly to the east of where they occurred, i.e. Hawke's Bay, Wairarapa and Wellington.  This is also why we have all of our volcanoes in the North Island.

In the bottom of the South Island we have the opposite with the Australian plate subducting under the Pacific plate, so we also get deep events here.   In the middle, for most of the South Island the two plates are colliding and grinding past each other, and this is how we get our Southern Alps (its also home to our famous Alpine Fault.)

You can see exactly how the plates are moving on a cool diagram here.

For those interesting at looking at quake patterns we are still working on our 'Quake Search' function on our website, which at the moment stops at September 2012 (when our new automated system came in).  This feature allows you to search for quakes using specific dates / location / depth and size and have then the quakes as dots on map (which you can click on) or the data in a spreadsheet.   We hope to have this up and running very soon!, below is an example of what it will look like (its still being jazzed up).

Lake Grassmere Quake Rapid Response

Last month after the M6.5 Cook Strait Quake four of our team went down to Marlborough and installed some temporary instruments to help us better locate the aftershock sequence. I wrote a wee blog on their travels down south as well as what happens at GeoNet HQ after a large quake, you can read it here.

This month the area decided it wanted more action and the M6.6 Lake Grassmere Quake shook up our Friday afternoon, So a rapid response team of Lara, Caroline and Daniel was sent down on Wednesday. Their goal was  to change batteries in the sites set up in the last trip and get the data cards from them, which will include the M6.6 quake data. They have also installed 4 new temporary instruments (three strong motion and one short period), slightly further South from the instruments put out last month, to again help better locate the after shock sequences.

Below are some pictures of their work, heavy rain and dirt farm tracks meant it was safer to get to the sites via helicopter.  This is also Carolines first week working at GeoNet - what a start!

 

Lara and Dan putting the fence around the site at Glenlee Station (SP on the map)

Heading off to the Awatere Valley

Lara, Caroline and the helicopter pilot at Muller Station, with a rainbow!(SM3)

Lara and Dan setting up the Strong Motion instrument at Gladstone Station (SM2)

Caroline supervising Dan digging at the last site, Glen Orkney Station (SM1)

GoogleEarth showing the location of the four new sites (green triangles) and the two large quakes

Rapid Response - finale

Following on from Tuesdays post on what our rapid response team were up to (and what happens at GeoNet after a large quake) here  I have some more pics from the teams final day out installing temporary sites.  In total the team deployed 8 new sites in and around Kekerengu, Renwick, Cape Campbell, Wairau, Seddon and White Bluffs.

A strong motion sensor was added to the existing Cape Campbell site

Sam installing the strong motion sensor

Dan and Todd at Kekerengu

Lara setting up the weak motion site south of Renwick

Sam with his trusty spade

The team all finished after installing a strong motion site at the Seddon Fire Station

Cook Strait Quakes : Rapid response team - and what happens at GeoNet HQ after a big quake?

Dan packing a seismometer

RAPID RESPONSE 

Following the weekends quake activity we had a rapid response team travel down to Marlborough yesterday, they will install temporary instruments to improve the quality and quantity of data being recorded by our network of instruments.

Loading up the vehicles

After loading up two vehicles the team of four were on the ferry and over to the South Island.
The next morning the team then split up into two, With Dan and Todd traveling to Wairau Valley to install a strong motion site, and then onto Port Underwood to install a weak motion site. 

The other team of Sam and Lara were being tailed by the TV3 Campbell Live cameras for the morning while they installed a combination site (weak and strong motion instruments) south west of Seddon in the hills, and then they were off to White Bluff to install another.

Strong motion instruments record the larger damaging shaking from earthquakes, while the weak-motion sites are more sensitive and record the smaller shakes.

I have pics from the teams below and a map showing where the places they have traveled to are, i also have a more detailed blog on how we set up temporary sites here

First strong motion site installed in a Wairau Valley Garage

Port Underwood site 1/2 way through

Dan and Todd at Port Underwood

Map showing the site locations, Stars are the largest quakes

 

Planning where they are going

TV3 cameras filming

Seddon combo site all finished

 

What happens at GeoNet HQ after a big quake?

Fridays 5.7 showing on a screen

We have a lot of different people who all come together after a large quake, each work in different areas of science and at the end it all comes together so we can figure out what is going on under the earth.

To start off with we are usually standing around looking at the screens showing the quake details, for a change on Friday most of us in GeoNet felt this event.

We have a duty officer on duty 24/7, their main role is to check the location of the quakes (after our automated system SeisComP3 )  but

The media are around lots

during a larger event they become 'media stars' with of lots of phone calls from the media and in events like this weekends, the news crews often come into GeoNet to do TV interviews.  This happens right in the middle of GeoNet in our 'media room'. This is also where we have our meetings and our offices are located off (so sometimes we are sneaking around behind the camera trying not to make too much noise)

A meeting of scientists all working on the quakes

 

The scientists all working on the quake sequence (from GeoNet, GNS Science and other occasionally other agencies like NIWA) have also been meeting here twice a day to discuss who is working on what, and their findings. Each have their own specialty but in a large event they all come together so we can try and figure out what is happening and what possibly might happen in the future.

Communication team working on getting the info out

We also have a 'crisis communications' team, who all come from different parts of GNS Science and GeoNet, and together we make sure that the current science information is getting out to the public, and what other information we need to get out.

So next time there is a large earthquake, you read a news story or see a scientist on the news - you now know what is going on behind the scenes.

A weekend of Earthquakes - what is going on???

I spoke with this weeks (lucky) duty officer Anna Kaiser who said :

At this stage we might call it an earthquake "doublet" with two quite closely spaced similar sized events in very similar locations. And there have been several aftershocks over M4 following this mornings earthquake  (where there was only one following Fridays).

Historically there have been several quakes over M5 in the general Cook Straight region in the last decade, and there was also an earthquake swarm in 2005. Back in 1977 there was an M6 in a similar location and depth.

The pic above shows a live shot of aftershocks being recorded by our instruments spread out over NZ.

What is an aftershock?

Aftershocks are earthquakes that follow the largest of an earthquake sequence. They are smaller than the mainshock, can continue over a period of weeks, months, or years, and In general, the larger the mainshock, the larger and more numerous the aftershocks, and the longer they will continue.

A section of the aftershocks following 5.8(yellow) on July 21

Aftershock Rules?

A common aftershock  'rule-of-thumb' applies to the magnitude, quite often ‘the largest aftershock will be one unit below the magnitude of the main shock'. So if you have a magnitude 8 earthquake, you would expect a magnitude 7 aftershock. So in this case with this mornings magnitude 5.8 earthquake, we would anticipate a magnitude 4.8 aftershock. and we got a 4.9!  

There are other rules involving a bit of math and the amount of aftershocks and their rate of decay, with the second day having half as many aftershocks as the first, and so on. But in general the magnitudes will get smaller and the amount of quakes less frequent over time, though this can vary., such as this weekend when you get another large quake.

Of course as this is the earth we are speaking of, it does not always play by the rules!

Why so many earthquakes?

In New Zealand, the Australian and Pacific plates push against each other along a curving boundary. At the southern end of the South Island, the Australian Plate dives down (subducts) below the Pacific Plate whilst in the North Island the opposite situation occurs with the Pacific Plate being pushed under by the Australian Plate. In between, through most of the South Island, the two plates grind past each other along the Alpine Fault. The Hikurangi Trough marks the collision boundary to the east of the North Island, and is where oceanic lithosphere (the Pacific Plate) descends into the Earth’s interior as a huge inclined slab.
 

Is this normal? 

Yes!  Because of where we live (see above) we get lots of earthquakes, some of them are large and scary. It does occasionally seem like we are getting more than normal, but its just how the earth works.

For example here is a map showing quakes over magnitude 5 from 1992 -> 2012, and you can see they tend to follow the line of the plate boundary.  

There is also the fact that we have the internet, smartphones etc. and are more aware of what is happening around us, where as before you might not know unless you felt an earthquake.

What does this mean? 

Unfortunately we don't have earthquake crystal balls just yet, so we can't say if this means 'the big one' is coming, or if this sequence will stop 'the big one' etc.  All we can do is be prepared - so check out the Get Ready Get Thru website  for what to do before, during and after an earthquake.  

You can also read more on a post i did here Lots of earthquakes - what does this mean?