Dr. Will Homoky – NERC Research Fellow at the University of Oxford.
This month I explored active lava flows entering the ocean from the Hawaiian volcano Kilauea. I got so close to lava I even poked a stick in to it. This blog tells how the chance arose, what it was like, and why I would like to return.
Surface lava flows from Kilauea at dusk. Photo credit: WB Homoky
Mount Kilauea has been continuously erupting since 1983 and I was a child the first time I saw documentary films of these lava flows. Relentlessly, they spill through the forest towards to the ocean and claim people’s houses on Big Island. These past few weeks, Kilauea has been very active and a cliff collapse by the ocean has produced an impressive cascade of lava where it flows from the Puʻu ʻŌʻō (roughly pronounced poo-oo oh-oh) crater and enters the sea near Kamokuna.
I didn’t only visit Kilauea to satisfy a childhood wonder of lava. These days I am interested in how rocks dissolve and supply essential elements for marine life in the oceans. Young volcanic rocks such as these might be rich pickings for the ocean, because they are packed full of biologically essential elements that might more easily be dissolved than in other types of rock. There is a lot left to learn about these processes in volcanically active environments such as this though.
I was in Hawaii to give a talk on the subject of rock dissolution on the neighbouring island of Oahu – part of an Aquatic Sciences meeting hosted by the American Society of Limnology and Oceanography. I had the chance to meet many new faces, and existing collaborators from other countries. So I teamed up with Tim Conway, Associate Professor from Florida State University. Tim and I have been studying rock dissolution phenomenon using iron isotopes
We embarked on a trip to explore the potential for doing oceanographic fieldwork where active lava flows meet the ocean. Marine scientists have already studied seawater chemistry in some pretty challenging places, such as remote high-temperature hydrothermal vents in the deep-sea. So how hard can it be to study surface water chemistry a few metres from the shoreline? Well, quite hard indeed, we have concluded.
For starters we needed a research vessel up to the job. On the top of our priority list, we wanted a vessel that would be armoured against intermittent bombardment from volcanic ejector, and would be comfortable in very hot and potentially acidic waters. It also had to be agile enough to accelerate in and out of a ‘danger zone’, where the risks posed from the lava and frequent cliff collapses could change suddenly. Lastly, all our manoeuvres had to be performed while riding over Hawaii’s famously wavy Pacific ocean.
The only boat we found up to the job was operated by Ocean Lava Tours. Purpose built, this boat was a twin-hulled passenger speedboat, made entirely from aluminium, and powered by 1000 horsepower of outboard engines. It did not resemble any research vessel that I have been on before. It was adept at moving us close to, and far away from, the lava quickly. However, it was not suitable for holding a geo-stationary position, or deploying any equipment over the side. Even a secchi disk would have presented a challenge, let alone a full CTD and water bottle sampling rosette or piloting a remotely operated vehicle (ROV). So our notions of planning any ‘routine’ oceanography were quickly abandoned.
A lavafall from Kilauea entering the Pacific Ocean at night. Photo credits: WB Homoky
At night, visible light was provided by the irradiance of the lava itself. Lava spewed from a pipe in the cliff face and fell freely through the air, plunging in to heaving ocean swell below. Clouds of steam engulfed us, and frequent explosions of quenching lava blew into the sky. Meanwhile, the ocean shifted our position continuously, and our thoughts soon turned from planning a water sampling strategy for dissolved trace elements, to the thick and sulphurous plumes of steam we were being tossed around in.
What we’ve learned is that performing a detailed study of chemical exchanges during ocean mixing with active lava will not be straightforward. Nevertheless, even the most rudimentary impact on the local ocean was staggering to witness. For hundreds of metres around us the ocean was so hot, it visibly steamed into the warm tropical night sky. Unlike deep-sea hydrothermal vents, where seawater mines heat and metals from deep from below the seafloor, the heat source, minerals, gases and ocean exchanges are all occurring violently right at the ocean surface – perhaps an uncommon but fascinating environment for geochemistry.
This trip was only ever going to be a reconnaissance to design future research, but it has given us a great deal of food for thought… For instance, it is worth remembering that new frontiers in ocean exploration might not always be far away from land. Albeit in this case, they have still proved hard to reach.