Tuesday, June 24, 2014

We can't feel your ghost quakes

Recent quakes close to Raoul Island
Today there was a large quake in the Kermadecs. This is thousands of kilometers North-East of New Zealand, not far off the volcano Raoul Island.

Unfortunately this quake, and a few other deeper distant events, cause our system some strife!  Our instruments are very sensitive and have no trouble recording distant quakes.

Now if we start with a wee earthquake 101: Earthquake waves are made up of P-waves and S-waves (amongst others). The P wave arrives first and and then the slower S-wave arrives, you can see this on the photo below.

M7.2 Japan Quake arriving on our stations

 The delay in the arrival of the S wave (as well as a few other depth related factors) causes our automated quake system SeisComP3 to think that there were actually multiple large quakes in New Zealand, as shown on our app below.

 
 
 We have nicknamed these events 'Ghost Quakes'.

Todays event even gave us "Ghost Aftershocks" with numerous mag 3 and 4 events being posted due to the aftershocks from the large Kermadec event.

We are always working on our automated system and are trying to teach the system to stop doing this, it is a tricky task however!  99% of the time our system works amazingly and you get good quake info really quickly.  If you do get alerted to a large quake the best thing to do it check our website and see if it has been reviewed by one of our team.  Another trick is to check the 'felt reports'  if a large quake has none, its a bit suspect!


Friday, May 23, 2014

Quakes, The Final Frontier ...

Here is something a wee bit odd for a Friday, someone asked me if there were quakes on Mars, would they be called Marsquakes? An interesting question! This led me to find the following article: 
So the moon gets Moonquakes!  

Now how do we know this? The same way GeoNet knows about quakes here in NZ, seismometers! 

Between 1969-1972 four seismometers were placed, by Apollo astronauts, at their landing sites around the moon. The data was radioed to earth until they were switched off in '77.

This data is still being looked at today, and using improved technology, now available, the data is increasing our knowledge of the moons core. 

Here's a pic of Buzz Aldrin deploying a seismometer on the moon! (NASA) 


 Now back to Mars ....

A seismometer was installed by one of the Viking landing probes in the '70s. Now it's a tad windy on the surface so the data has been noisy and no clear quake data has been obtained.

In 2016 there is a new Mars lander launch planned and this (as well as some other fancy toys) includes another seismometer. The InSight has equipment that will drill down so sensors will be placed away from the surface noise and will hopefully give clearer readings. Much like our borehole instruments in the Auckland CBD. 

And yes they will be called 'MarsQuakes'

Thursday, January 23, 2014

Eketahuna Earthquake Response

This week I got to go back to my old hometown, and visit my old school! 


 
Wednesday morning I traveled up to Eketahuna, the location of this weeks M6.2 earthquake, with Lara and Sam to install three temporary strong motion instruments around the earthquake epicenter. These will help us get better coverage over the aftershock area, as the more instruments you have, the better earthquake size/location information. 



Charlie beside the instrument




Our first stop was my old primary Eketahuna School, here we checked in on technicians Daniel and Charlie who had just finished upgrading the permanent strong motion site EKTS we have at the school. 




We then traveled out east  past Alfredton, towards the quake epicenter, where quite a few roads were damaged like the picture below.
SH53 had lots of damage


There wasn't a lot of cellphone coverage so it was tricky to find a place for our instruments, they also need power and to sit on a concrete pad. Lara had done a lot of prep beforehand and had narrowed down some ideal areas, but we still had to drive around a fair bit looking for houses that had both cellphone coverage, and an ideal area for the instrument.




The first farm we visited were happy to let us install some equipment, so our first strong motion site is in their chiller room.




Sam busy installing
The farm is on top of a small hill so one of the few places in the area with excellent cell phone signal, which we need as the data is sent back to us via the cellphone network.


Sam has to secure the cases to the concrete floor, he does this by drilling and using bolts, so we really appreciate the home-owners letting us take up power, space and drill holes!


The basalt then gets bolted into the case, this is the instrument which records the shaking of the earthquakes.


The Basalt







The sites all have external GPS which gives us accurate position and, more importantly, accurate timing of the quakes.

 

Epicenter just over there



On our way to the second site we drove right past the (rough) M6.2 quake epicenter location (beside Pa Valley Road)  just over in the paddock!  As you would expect there was a lot of road damage and slips around this area.




Our second spot was a tad south at Ihuraua, the farmer had some impressive cracking on his property, he kindly let us use a small room in one of his sheds. 







Sam drilling















After each site is installed Sam checks to make sure the GPS is talking to the satellites and then calls work to make sure the data is coming through.





 Although a large earthquake is not the most ideal time, it was quite neat to be in that area again, as its been some time since i was that far out of Eketahuna.  And two of our instruments ended up at homes of people that knew my family.

 


 Most of the people we had spoken to had some damage, things fall over and break in their houses, cracks in walls and paths etc.  Its important if this happens after a quake, to not just pick things back up and put them how they were. As we live in such a seismically active country, we always have to be prepared for earthquakes. 

So this is a good time to make sure heavy items are secured to the wall and wont fall over again, valuables on shelves wont fall off and break. And to check your chimneys and hot water cylinders for damage and protect them for the future.   EQC have a really handy website called Fix. Fasten, Don't Forget  which makes this process really simple, it has great information on how to protect all of these things and more.

Also to help get this important message across  GNS Science, MCDEM and EQC have gotten together to share a reminder on preparing for earthquakes

 A little effort now, will save a lot of heartache and nuisance later on!




And finally, its always important to wear appropriate
clothing ...






Wednesday, December 18, 2013

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.

Tuesday, December 17, 2013

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:

video

Tuesday, December 10, 2013

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

Tuesday, October 1, 2013

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!