They are not sure how large the magma chamber is, but some initial testing suggests it may have been put in place by activity from Kilauea in the 1950s, perhaps even the 1920s.
Professor Marsh said the chamber was docile and slowly cooling. The consistency of the magma was like chilled pancake syrup, he said.
It is hoped the site can now become a laboratory, with a series of cores drilled around the chamber to better characterise the crystallisation changes occurring in the rock as it loses temperature.
The magma is a dacite, making it chemically distinct from the basalt which forms nearly the entire mass of the Hawaiian Islands and the surrounding oceanic crust. It has a much higher silica content.
So they find magma nearer to the surface than they thought they would, and it’s related to an old eruption, and it’s not the kind of magma that usually reaches the surface in Hawaii at all. Very nice result, and it may even all make sense. (If I remember correctly, the lava that reaches the surface in Hawaii is distinctive for being much less viscous than continental magmas, so the more viscous stuff might just all be in big lens-like blobs cooling somewhere a couple kilometers down.
And from the geothermal energy point of view, getting 1000C instead of 200-300C is an incredibly useful result if it can be duplicated. Somewhere around double the efficiency, which means half the energy flow can produce the same amount of useful power.