Friday, 22 January 2010

Kilauea eruption overflight

I went on the weekly Kilauea eruption overflight on 7th January. It was definitely up there with my best experience on Hawaii. The volcano is currently erupting in two locations; at the summit and on the East Rift Zone. We took off from the park visitor centre and headed for the Halema'u ma'u crater at the summit then onto the Pu'u O'o vent on the rift zone (above) and over to the flow fields down by the Ocean.

We landed on the flow fields to put a new memory card in a webcam and took a lava sample from an active lava breakout (above). There is a lava tube system running underground from the East Rift Zone down into the Ocean. Lava can breakout from these tubes when a magma pulse is sent through the rift system. We sampled the lava with a hammer then cooled it rapidly in a bucket of water. The hardened sample is then bagged and sent off to the lab for analysis.

Normally lava flows have been flowing directly into the ocean producing the plume mentioned in previous posts. The ocean entry has temporarily switched off due to a lack of supply to the rift zone (the above photo shows the absence of any plumes). This lack of supply be a blockage which has caused a backing up of magma to the summit area resulting in the increased activity as described below.

We also landed right by the Pu'u O'o crater where we cleaned a webcam screen as it gets very murky from the continuous gassing.

Approaching the Halema'u ma'u vent within the Kilauea caldera.

The above picture is looking down into the Halema'u ma'u vent. There has been a lava lake present in the vent for some months but recently activity has increased and the lake has risen to high levels. The picture above shows a rapid lava stream rushing from an upwelling to a draining point on the North side of the vent. A second lava stream is cascading down onto this flow.

images courtesy of USGS
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Monday, 4 January 2010

HVO Fieldwork #2

We ventured down into the Kilauea caldera with gas masks at the ready to undertake a kinematic gps survey. Andy Pitty and I did the gps while Ingrid and Mike Poland went ahead to do a gravity survey. The halema'uma'u vent (above) has been active since March 2008 so the area we were working in is off limits to the public.

Unlike the static GPS units mentioned in my previous post, these units are designed for mobility. The survey involves taking readings at set benchmarks along a survey line in the caldera. Any small changes in the position of the benchmarks give indications of deformation which could preceed an eruptive phase.

A gravity survey was also conducted. These expensive and incredibly sensitive devices measure the torque on a metal spring attached to a weight to measure local gravity anomalies. These anomalies could indicate movement of magma beneath the surface.
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images courtesy of USGS