07-02-2008, 03:04 AM
There has always been a connection between the summit magma storage system and the east rift activity. The lava, or magma as it is called before it reaches the surface of the volcano, comes up from deep within the earth into the summit magma chamber, and from there, flows through the mountain down the rift to be erupted in the Puu Oo area. The new summit vent at Halemaumau is connected to the same summit magma chamber. It is all hydraulics i.e., a fluid system in which pressures are transfered through a liquid body. With the array of sensitive instrumentation that HVO has in place, both seismic equipment that measures the vibrations (noise) made as lava moves through the earth, and deformation equipment that measures the mountains surface changes in response to the pressure changes within, they are able to 'see' changes as they occur and plot the movement of forces through the volcano's internal plumbing system. There is much more concern for what might be happening within, and what that might mean for potential changes in eruptive activity, when there is no connection observed between the summit's behavior and the activity down on the east rift. That was the case for a while preceding the changes that occurred with the eruption last summer.
The explosive activity at the coast where the lava enters the ocean is only related to the way that lava is entering the ocean. If a situation develops in which water can enter a confined space that is otherwise occupied by lava, the water is rapidly heated, expands to steam, and will explode. This is what we are currently seeing at the coast. But, it has no relationship to the internal plumbing system of the volcano as a whole.