The Lumen arc lamps and the glass roof provided the PLU crew with an almost three hundred and sixty degree daylight view to a distance of ten metres.
‘What can we expect to see?’ asked Smith.
‘It’s not widely appreciated, but there are over ten thousand volcanoes below sea level. As a consequence, over eighty percent of the earth’s volcanic activity takes place on the sea floor. There is a continuous chain of volcanic accumulations rising up to two kilometres from the ocean floor along a continuous line from the Arctic to Antarctica. Off the main mid-Atlantic chain there are hotspots, the Canary Islands being a good example. There are multiple fissures and dykes all along the sea floor.’
O’Farrell was becoming all too aware of the enclosed confines of the small craft, which seemed to get smaller all the time. Talking helped her manage her nerves. She completed the answer to Smith’s question.
‘I expect that we’ll see many ‘black smokers’ as we call them. This common form of volcanism gives rise to basaltic pillow lava and minor gas explosions. These quieter eruptions are in contrast to what are called pyroclast events, derived from the Greek words pyros meaning fire and klastos meaning broken, that involve the explosive emissions of lava bombs and debris. Dozens of minor seismic events are recorded around and at right angles to the mid-ocean ridges. If not today, over the coming weeks, we should be able to use our seismometer to detect activity.’
It was Smith’s turn to be at the receiving end of random information. He asked the obvious question. ‘How will you know that a smoker is not a potential pyroclast event?’
‘Our seismic readers will go off the Richter scale if a major eruption is brewing up deep within the sea floor. We’ll also see the extrusion of large bubbles of gas prior to any explosion. Magma, a viscous mix of molten rocks that rises to the sea floor, that contains highly volatile elements such as sulphuric acid will be released if the pressure of the gases exceeds that of the surrounding material. Few such incidents have ever been observed.
O’Farrell was getting into her stride. She continued, ‘In May 2009, an ROV witnessed two active sea floor volcanic vents near Tonga Island in the Pacific at a similar depth to where we are. This is the reference case history taught at university. Over a seven-day period, multiple small eruptions occurred at the main vent and at lateral locations. The ROV’s video witnessed underwater fire fountains, billowing sulphurous gas emissions, bright orange lava and glowing gas bubbles as wide as a metre across.’
‘Wow, let’s hope we’ve a less exciting experience,’ said Smith.
‘Below the sea floor’s surface, the rigid lithosphere is thinner and is closer to the earth’s mantle where most of the transfer of matter and energy takes place. Only seventy percent of the sea floor has been mapped and explored. This is a major gap in science as the sea floor tells us so much about the internal structure and evolution of the earth.
‘Look ahead,’ shouted Smith.
Drifting into their vision from the chilling darkness was a pair of Minke whales about twenty metres long that seemed to pause in suspended animation metres in front of the PLU. The Lumen arc lamp highlighted their grey and black skin. Their eyes were enormous. Their wide stares unsettled everyone.
‘No need to panic as they are just curious and will not come any nearer.’
‘How do you know that?’ said Gallery, who was frozen to his seat in fear.
‘Their sonar told them we were here a long time ago. They made their way over to see what the noise was all about. Whales have never attacked a manned submersible and we’re trained to move around them. As long as we give them space, they will not bother us. I would guess that this pair, judging by the blemishes and barnacles on their skin, are a male and a female, at least thirty years old. They are probably migrating south. They eat krill and not humans, never mind humans in a protected shell. No need to worry.’
As Smith was talking, they disappeared into the dark abyss out of the range of the Lumen arc lamp.
Smith resumed his banter, erudite as always, as the PLU approached its target. ‘The PLU’s prototype dates back to Alexander the Great, who in 325 BCE descended into a harbour in a barrel and viewed his surroundings through a window made of the skin of a donkey. Fast forward to modern times, where manned deep-diving submersibles are constructed around a sphere made of an alloy of steel and titanium about two metres in diameter, which can resist the high pressure found at ocean depths. In most cases, manned submersibles have two pilots and one scientist on board. We had to cut corners for this voyage I’m afraid.’
Before he got a response from his passengers, Smith turned on the external communications system.
‘Paul are you receiving us?’
‘Yes Mike, clear as a bell. All ok?’
‘Apart from a close encounter of the whale variety that spooked Maeve and Andy, all is in order. The sonar shows we’re about fifty metres above the sea floor. I’m about to use the satnav to take us to our target area. Any more seismic readings from our British friends?’
‘No, nothing since the last set we spoke about during the briefing.’
Smith expertly slowed the PLU’s rate of descent and in so doing the main Lumen and secondary arc lamps began to illuminate the seabed. He was able to adjust the rate of descent and to obtain neutral buoyancy by releasing weights in the form of the iron pellets stored in six reservoirs on the sides of the PLU. He controlled the release lever mechanically.
‘I reckon I’m about four hundred metres from the location of the last seismic reading. We’ll proceed north-north-west to a depth of some fifteen hundred metres off the east flank of the Eriador Seamount.’
The main noise in the chamber of the PLU was the constant ping of the sonar. Casual conservation was put on hold as they glided over the sea floor.
Smith was careful not to drive the PLU too quickly. That would have the effect of stirring up a lot of sediment. Through the wide front porthole, they could see solidified deep grey layered lava tubes and lava pillows, some as high as twenty metres: remnants of volcanic activity that ceased a long time ago. These dark lava structures dominated almost the entire seabed with the only noticeable feature being higher ridges at irregular intervals. There was almost no vegetation on the barren sea floor.
‘Is that a basalt formation Andy?’ asked O’Farrell pointing to a low ridge of rock.
Basalt is the most common type of volcanic rock found on the sea floor.
‘Yes, it is. I wasn’t expecting to see …’
He didn’t finish his sentence as coming into the light were two three-metre tall active vents side-by-side. They spewed a yellow gas and oozed dim red lava.
‘My God,’ exclaimed Gallery.
Smith halted the PLU a safe distance away as the scientists observed all before them in amazement.
‘Not exactly what I was expecting to see, guys. Let the video roll so that we can transmit pictures up to the control room. Mike can you please zoom the main camera into the apex,’ said O’Farrell.
As the camera brought the mini-eruption into better view, McCrossan came over the communications link. ‘Mike, the Woods Hole team want you to take samples of the gas and the lava. Be very careful. They think this is an unstable fissure and you should keep your distance. Use the probes on the mechanical arms to get the samples.’
Smith turned on the light projectors located on top of the portholes and on the ends of the mechanical arms. They too were turned off during the descent to save energy. Once he could see the objective, he skilfully manoeuvred the PLU within four metres of the vents. PLU’s long telescopic grabber was designed to pluck samples from the seabed and to store the material in metal baskets that were positioned at the front of the craft. Smith had used the telescopic grabber many times before so had no problem separating two small rock samples and transporting them safely into the baskets.
‘I can’t wa
it to analyse these rocks,’ said O’Farrell. ‘But what interests me more is the composition of the gases and the emission rate. Can we get samples?’
‘No bother.’ smiled Smith who was eager to show off his skills as a submersible operator. ‘We’ve a Fourier transform infrared spectrometer that I will place over the vent. This will identify the gases and measure the flow rate. Andy, please turn on the remote infrared analyser switch as we’ll start to get readings as soon as I approach the vent.’
O’Farrell looked out the cockpit porthole as Smith moved the PLU nearer the orifice of the chimney. which was spewing hydrothermal fluid like a locomotive would at a temperature of 350 degrees Celsius: enough to melt PLU’s Perspex glass if they got close enough.
This was a ‘white smoker’.
‘Wow, Maeve, look at the sulphide and carbon dioxide readings. They are very high. Too high for my liking,’ exclaimed Andy. ‘What do you think Maeve?’
The PLU crew could not hear the gasp of anxiety that came from the geologists on the RV Celtic Explorer who had quickly come to the same conclusion. In their experience strong emissions of carbon dioxide were a precursor and a valuable indicator of new episodes of magmatic unrest. What they also saw were defined fluxes of sulphur dioxide, also a proven indicator of imminent volcanic activity.
‘Give us a minute,’ said Gilmore taking charge. He switched off the comms link with the PLU. He sought views from his colleagues. The recommended course of action was unanimous.
He re-connected the comms. ‘Andy, Maeve, the team suggests that you back off now. We’ve enough evidence to work with. We’ve shared the video footage and geochemical data with our British colleagues and American friends at the Hawaii Undersea Geological Observatory (HUGO) and Woods Hole. I know you have enough battery power for another hour’s exploration, but the view here is that you should start the re-surfacing procedures. Besides there is a front coming in from the west and surface swells will increase within the hour.’
‘Roger that, Gerdy,’ said Smith. ‘This first trip delivered more than we were expecting. I’ve no issues with a safe return to the mother ship. All right with you Maeve, Andy?’
Their silence was enough of a signal. He took the joystick and manoeuvred the PLU off to the left side of the vents and powered it up at a forty-five degree angle. Within ten seconds they saw a huge burst of lava from the vents that went ten metres high with small lava bombs scattering all around. Because they were in a confined space there was no audible sound. The seismometer needle on the front console started to shake as the characteristic zigzags filled the screen.
All that was audible within the cockpit was the soft noise of the PLU’s electric motors as the manned submersible started to ascend to the surface. The PLU’s crew had had enough excitement for one day.
CHAPTER 6
Reventon
‘Damian, where are you?’
Simon tried to control his emotions. Tears were welling inside him.
‘In the car park at La Cumbrecita. I’m dealing with an emergency. We lost four of our hikers who were on the Lomo de las Chozas viewing platform when it was hit by a sharp tremor. The outcrop fractured and they fell to their death.’
‘Jesus, help us,’ said Simon.
‘And Margarida and I are now trying to calm down the survivors of the group. They want us to help them recover the bodies. That’s easier said than done.’
‘I’ve another situation that’s an emergency.’ Simon was aware that Damian was under pressure.
‘Go on. Fill me in.’ Damian feared the worst. He knew something had happened to his nieces.
‘Maria and Claudine are missing,’ said Simon, his voice trembling. ‘We had arranged to meet them at the Reventon car park half an hour ago and they didn’t turn up. There was another tremor close to the Cumbre Nueva trail and it may have hit them. Their mobile phone is not responding.’
‘I could be with you in an hour,’ said Damian, trying to be helpful. He was still trying to manage the aftereffects of a serious incident.
‘Damian, we don’t have an hour. Ros is going to stay at the car, and I’m making my way up the trail to try and find them.’
‘It’s time to put the MD into action.’
‘The MD?’
‘It’s what I call my new camera drone: Margarida’s Drone if you must know. It will take me five minutes to set up and we’ll be flying thereafter. I’m on the opposite side of the Cumbre Nueva ridge. In fact, as the crow flies, I’m no more than five or six kilometres from the trail the girls were walking on. I reckon I could get the MD to the girls’ expected position within ten minutes.’
‘Get on with it then. I should be in that area around the same time.’ Simon was too worried to be polite to Damian who made allowance for the abrupt end to the conservation given the circumstances.
There is nothing quite like controlling a flying piece of technology and having it respond at will with fingertip precision. Damian had already damaged two inexpensive smaller camera drones, but in doing that he had honed his skills. MD came with a first-person-view live-feed feature. He could see the landscape in front of and below the drone on his laptop.
He didn’t dare tell Margarida, but her namesake MD was a top of the range machine. He had spent more than he could afford – two month’s earnings – to get all the latest features, including night-time infrared vision, a thermal sensor and DSLR camera lenses. If it helped save their nieces, Margarida might forgive his latest extravagance.
He took a line of sight to the top of the Cumbre Nueva ridge, which was almost 1,200 metres higher than where he stood. He released MD. She shot off at eighty kilometres an hour.
Damian had walked the ridge dozens of times so was able to spot familiar signs and landmarks in the moonlight when the video feed appeared on his computer. He reckoned the drone arrived about a kilometre from where Ros believed the girls to be. He slowed MD over the trail and pressed the wide lens and thermal image function buttons. MD followed the trail, or what was left of it, downhill from two hundred metres above the ground. The well-worn ash-based walking path was cracked everywhere and had settled in a series of jagged random mounds. What the hell happened here? He said to himself.
His iPhone rang. Simon’s name appeared.
‘Damian, where are you?’
‘Very close by, I guess. I’ve MD above the trail. I’ll turn on her arc light.’
As soon as he did, the night sky lit up with the best that LED could provide.
‘Wow,’ said Simon. ‘That’s some lamp.’
Damian had never used the arc light before and had reason to be impressed.
‘Damian, I can see the ground clearly. I’m about five hundred metres away down the trail to the right. Please guide the MD along towards me. I’ll use my mobile’s light so you can locate me.’
‘What happened to the trail?’ asked Damian.
‘It was struck by a narrow shallow earthquake that didn’t surface but caused the ground to disintegrate. Enough of that. We need to find the girls. Can you widen your lens and start searching on either side of the trail, I suspect they were thrown there by the force of the blast.’
‘Will do.’
Simon sat down for a short rest to catch his breath. He was emotionally and physically exhausted. He would not live with himself if his decision that the girls should hike to the car park had cost them their lives. These mountains were dangerous under normal conditions, but this was anything but normal. He was all too familiar with the lingering smell of sulphur and was glad he had packed his oxygen mask in case it became uncomfortable and necessary.
Damian shouted over the phone. ‘Simon, I found them. They are lying off the left side of the trail about a minute from where you are standing. They are prone, but the thermal sensor shows good body heat, so they are alive. I’ve a spotlight above them.’
‘Yes
, I can see it.’ Simon sprinted like a cheetah towards the girls. The sharp contrast of the MD’s LED gave him great visibility. Claudine was clearly concussed. Her breathing was shallow and slow. He decided to stabilise her first and did so by attaching his oxygen mask over her nose. Immediately she responded. She coughed violently. While covered in black dust, she didn’t appear to have any injuries.
As she opened her eyes she said. ‘I’m ok, look after Maria.’
Maria was in a much worse state. Apart from a deep gash across her forehead and multiple scratches to her arms and legs, she was struggling with her breath. He bent down towards her mouth to resuscitate her and was immediately met with a strong smell of sulphur. He knew that not only was she knocked out by the impact of the quake, but that the associated sulphur emissions could be poisoning her.
Claudine sat still, silent and stunned, and watched Simon give mouth-to-mouth resuscitation to Maria. After six blows of air into her lungs he quickly attached an oxygen mask and turned up the flow to full. The response was also immediate. Maria’s eyes opened. She emitted a deep gurgling sound from the depths of her lungs. She coughed hard and spewed out. Once she cleared her air passage her breathing became less of a struggle. Simon held her close and smiled knowing she was on the mend. He got an even bigger smile back and a loving look from her blue-grey eyes. He took off the oxygen mask.
‘Where are we?’ said Maria.
‘No longer on the dark side of the moon. Take it easy now. I’ll look after you,’ said Simon, lovingly.
She tried to laugh, but it hurt.
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