Operation Iceberg

Operation Iceberg and other fun in Greenland - over the last few summers I have been working with a number of colleagues up in Greenland.  It's the best kept secret holiday location if you want stable weather, blue skies and 24hrs of daylight.  Rather than blogging here I have written a short piece for the "Travelling Geologist" - Chris Spencer - check out some of his great blogs on http://www.travelinggeologist.com/

richard 

Peering inside volcanoes: A guest post by Oliver Lamb

Picture yourself here. You are a scientist monitoring an active or erupting volcano. In the past, this volcano and others like it have produced lava domes which are prone to suddenly and violently explode or collapse to produce devastating pyroclastic flows, often without warning. Unfortunately, it's this sort of behaviour by Sinabung in Indonesia that recently took the lives of 14 people (see the video below for a spectacular example from Sinabung). So what can you, as the scientist, use to work out when the growing dome is going to explode or collapse next? What is already known is that the transition from quiet to violent activity during dome growth is because of a complex range of processes, particularly before explosions.

Fortunately for scientists like me, active volcanic systems produce a wide range of seismic signals prior to and during an eruption and these signals are easily picked up by seismometers deployed around the system. For my PhD at the University of Liverpool I am carefully analysing the seismicity from recent or ongoing dome-forming activity, focusing particularly on any signals that can tell us something about the conditions within the volcano before explosions or dome collapses. Hopefully by the end of this project, I will have looked at seismicity from at least four different active volcanoes: Volcan de Colima, Santa Maria, Mt Unzen and Mt. St Helens.

'Drumbeats' recorded over a 24 hour period at Mt St Helens, 15 November 2004

To give you an idea of the size of the dataset for this project, I've included the snapshot above of the seismicity from Mt St Helens during its eruption from 2004 to 2008. What you're looking at is the seismograph from a single day during this eruption, and each of those peaks is an individual volcanic earthquake. Now imagine trying to analyse each event, every day, every month,  for well over a year, then you have a gigantic number of events to look at! Thankfully, at least for my sanity, we have tools which we can use to automatically count all these events and measure different traits about each event. These traits include how big the event was, how long it lasted for, how long was it since the last event, the frequency content and much more. With these tools, we can now begin to track how these events change over time and begin to get a better idea of what's going on as the eruption progresses. I have already used the tools on seismicity from  Mt St Helens, and by my latest count the volcano experienced well over 500 000 seismic events from November 2004 to March 2006, an average of around 50 events per hour. I hope that emphasises how large the dataset is!

Left: Volcán de Colima, Mexico, during more peaceful times, taken August 2012.
Centre: Mt Unzen, Japan, nearly 20 years after it ceased erupting. (Credit: J. Kendrick, Liverpool).
Right: Santiaguito, Guatemala, taken December 2007. (Source: photovolcanica.com) 

But the project doesn't stop there. There are plans afoot for a whole raft of other analytical methods to be used. Methods such as locating each event as the eruption progressed, looking for events which may have come from the same source, and then some statistical analysis on top of that. Eventually, armed with all the geophysical results, my project will then begin the experimental phase. During the experiments, I will be placing samples into similar pressures and temperatures as we think the seismicity is being produced in, and break the samples apart and record the resulting acoustic emissions. The current idea is that by the comparing the experimental and volcanic waveforms, we can then help figure out what's going on inside the volcano during a dome-forming eruption.

The author, on the south flank of Volcán de Colima in July 2012

There you go, there's my project in short. For those of you who don't know me, I'm Oliver Lamb and I am a first year postgraduate research student with the Department of Earth, Ocean and Ecological Sciences at the University of Liverpool. If you have any questions or comments about what I've written here, then please feel free to get in touch with me via e-mail, olamb245@gmail.com, or find me on twitter, @olamb245. Thanks for reading!

Iceland - Orca 2014

Grundarfjörður

Iceland - Orca 2014

Iceland - a change of scene and most definitely a change in temperature since Tanzania!  I have spent the last couple of weeks working with the University of St Andrews Sea Mammal Research Unit (SMRU) on a project led by Dr Patrick Millar  investigating methods for measuring and monitoring the health/body condition of cetaceans, in this case, orca. 

Orca off the bow

Our part of the project will be testing sonar as a tool for specifically measuring body condition from body measurements.  This might seem like a far cry from mapping seabed or reconstructing palaeo-landscapes, the more usual deployment of sonar in my work, but really it’s not such a far cry.  The idea is to use a new generation of very high resolution sonar to map in real time the acoustic reflections from the body surfaces of whales as they swim past the boat or as we can manoeuvre the boat into a position to observe their habits such as feeding.  Ultimately, if we can obtain consistent and representative measures of body dimensions then SMRU might be able to observe aspects of body condition change during a season.

The sonar we are working with is the latest 3D sonar from CodaOctopus the Echoscope.  This sonar sends out a broad spectrum of acoustic energy about two, main frequencies, namely 375kHz and 610kHz.  The energy is recorded on an array in 3D that allows the reflected signal to be correctly positioned within a cone of insonification that is about 50degree in width and height.  With the addition of positioning and motion reference to the sonar, together with an insonification rate of up to 10 pings per second it should be possible to track the whales in real time.  What we are up here determining is if we can not only track them and thus ascertain their behavioural characteristics but if the sonar will also give us the resolution to be able to make precise body measurements.  This will require quite a bit of processing to first remove any noise in the data such as the fish schools that the whales are often hunting, the clutter from wave action at the surface and the seafloor.

SMRU boat Tango with Echocope fitted to starboard

So here we are in Grundarfjordur, on the Snefels peninsular with the team (Filipa Samarra, Sara Tauares, Miguel Neves, Fedutin Ivan, Olga Filatora, Sebastien Houillier, Paul Wensveen, Kagari Aoki, Julie Becsau, Jose Guilabert, Melanie Chocholek and Luke O’Connor) that will also be making a record of photo ID, sound recordings, tagging whales with motion sensors and taking samples for biopsy.  Why Grudarfjordur? Well over the last few years there have been large number of orca that visit the fjords in winter to feed on the vast stocks of herring that congregate in the still, cold and somewhat protected waters. 

The setting is spectacular with snow-capped mountains of layered basalts surrounding the fjord. Sure, its cold with frozen ground and even the snow at sealevel with an icy crust but that does not seem to daunt the Icelandic horses with their heads bowed to the constant north-easterly winds. 

Our mornings start with a check for orca in the fjord.  If there, and this is usually given away by the flocks of gulls and the odd eagle that flock above the feeding whales, then we launch the boat.  The sonar is deployed after making observations of behaviour in order that we can determine if the sonar is having a detrimental effect on the orca and then it’s a gentle approach to groups where they are feeding in order to obtain data.  On a good day we will get sonar data, photo ID of the whales and if lucky some biopsy samples. 

Image from Echoscope showing large male orca and young orca in background

Processing is going to take some weeks to obtain quantitative information but at the end of the trip we have managed to record some great data showing behaviour including groups working the herring schools up to the surface for feeding.

There is a great team here and it’s a real privilege to work on this project and in this part of the world – well worth a visit if you are interested in whales, outdoor scenery or of course for views of the northern lights!  Next time I must remember to bring my ice climbing and skiing gear for those days that the whales do not turn up!