Daily Journal

Day 4 | July 21, 2005

Traveling to Oshima

The team has been based on Niijima for the past three days. Today, we traveled by ferry to the nearby volcanic island of Oshima, where we will spend three nights before returning to Tokyo, completing the first leg of our journey along the Izu chain.

Oshima is unique amongst the Izu Islands on our itinerary, as it is the only one that is entirely basaltic in composition, i.e. the chemistry of the lavas most closely represents the underlying mantle source. The youngest volcanic center on the island has been active for only 20,000 years and erupts with an average periodicity of 20 years. The most recent eruption occurred in November 1986, when the volcano produced a series of dramatic Hawaiian-style fire-fountains.

Interestingly, there was an increase in the water temperature of wells on the island following the eruption.

This afternoon, we headed out into the mosquito-infested jungle to sample water and gases from two of these wells. We also wanted to check the water temperature to compare to the temperature at the time of the eruptions.