Volcano Watch — Munching Mauna Loa - Creatures of the Deep Feast on the 1877 Kealakekua Bay Submarine Lava Flows

The eruption took place entirely under water and is in fact the only known submarine eruption in Hawai`i in the past 200 years. As reported in the February 28, 1877 issue of the Hawaiian Gazette, the steamer Kīlauea ventured around Palemano point into the bay and encountered not only columns of steam and volcanic gas rising from the waters, but also blocks of semi-molten lava 60 cm (2 feet) across floating on the water. Local residents told the steamer's crew that the violent submarine eruption from one of Mauna Loa's radial vents was accompanied by a strong earthquake felt in the nearby settlements of Ke`ei and Ka`awaloa, along with 1-m (3-ft) wide ground cracks that split inland nearly 5 km (3 miles) from the eruption site.

The Kīlauea was lucky - submarine volcanic eruptions can be extremely hazardous to passing ships, as the Japanese research vessel Kaiyo-maru learned in 1953. All 31 people on board were lost when the ship passed directly over the erupting Myojin-sho volcano. Rapidly rising gasses ejected from the undersea volcano decreased the water's density and hence its ability to support the heavy ship, causing it to slip beneath the waves. Luckily for the Kīlauea passengers, their captain steered away from the eruption so that they could safely view the undersea eruption.

The waters of Kealakekua have long since calmed, yet the 1877 lava flows are still of great interest to scientists. Following up on mapping of the flows done last year, researchers entered the bay a few weeks ago aboard the research vessel Ka'imikai O' Kanoloa, funded by the National Oceanic and Atmospheric Association's Underwater Research Program in collaboration with the University of Hawai`i and Scripps Institute of Oceanography. They sought to learn how underwater lava flows are dissolved and used for nutrients by microorganisms that dwell in cold, deep water.

The 1877 eruption provides the perfect natural laboratory to study this process over decades, because the age of its basalt flow is so well known. To gauge how voraciously the microbes devour basaltic glass in a short time, scientists last year used the small two-person submersible Pisces to leave behind several samples of fresh, crushed rock erupted from Kīlauea's Pu`u `O`o vent. Samples of Pu`u `O`o glass were placed at four depths, 200 m, 750 m, 1000 m, and 1550 m, (650 ft, 2500 ft, 3300 ft, and 5100 ft,) where the water temperature plunges to a chilly 3 degrees Celsius (37 degrees F).

This year, the Pu`u `O`o samples were retrieved along with pieces of glass from the 1877 eruption. In the coming year, researchers will analyze samples to gain a deeper understanding of how fast the lava is dissolved by microbes in 1 year (Pu`u `O`o samples) and 126 years (1877 eruption).

Why would anyone want to learn so much about how underwater microorganisms eat lava rock?

"The cold, wet environment at the depth of the 1877 eruption provides a good approximation for conditions one might expect below the ice caps of Mars or on Jupiter's moon, Europa - both of which are leading contenders in many scientists' minds for potentially harboring extraterrestrial microorganisms," explained Scripps PhD student Brad Bailey, one of the researchers on the cruise. "What's more, these conditions are close to those that might have been found here on Earth billions of years ago as life began."

As unlikely as it may seem, Kealakekua Bay and Mauna Loa together create an excellent model for conditions potentially found beyond this world that could harbor extraterrestrial life. Will there be future underwater eruptions in Kealakekua Bay or elsewhere just off the Big Island? Probably, and they will no doubt provide a tasty snack for the tiny creatures of the deep.

Volcano Activity Update

Eruptive activity at the Pu`u `O`o vent of Kīlauea Volcano continued unabated during the past week. Fresh lava from vents within Pu`u `O`o coat the crater floor, and occasional spatter can be seen above the crater walls. Both the West Gap Pit vents located immediately outside the crater and the rootless shield complex at the top of the Mother's Day Flow were active throughout the week. Glow from flows within the crater and the overturning perched ponds of the shields light the night sky. No active flows are on Pulama pali or the coastal flat below Paliuli. No lava is entering the ocean.

There were no earthquakes reported felt in the week ending on December 24.

Mauna Loa is not erupting. The summit region continues to inflate. Seismic activity remains very low, with no earthquakes located in the summit area during the last seven days.