[Geysers] Fw: Rotorua Blowout

[Ashley Cody]

----- Original Message ----- 
From: Ashley Cody 
To: geysers at wwc.edu 
Sent: Monday, February 07, 2005 11:29 AM
Subject: Rotorua Blowout


A brief note from Rotorua NZ. On Tuesday 18 January a hydrothermal eruption was witnessed by a member of a Maori dance group who were gathering outside Lake Plaza hotel, on the shore of Sulphur Bay. They were about 1 km west (~0.5 mile) from site, which was at mouth of Puarenga Stream at its delta into Lake Rotorua. Area is a big expanse of boiling solfatara (~10 acres?) with a long history of such eruptions. 

The one on Tuesday 18 January sent up a vertical column of steam as a big mushroom cloud, that suddenly appeared and caught attention of people outside hotel. They thought it went about 30 m high and after a few minutes all died away. I visited site last week and there is a new crater ~15m diameter, boiling and overflowing 2-3 litres/sec. Blocks of ejecta <0.5m dia. thrown to <10m away and muddy debris to <25m radius of crater rim. I have photos of this and could e-mail them to anyone (~20 Kb jpegs?) if you e-mailed me at codya at wave.co.nz

In Whakarewarewa Village, a ground collapse occurred in early January between the main hot spring Parekohoru and the Oil Baths. Area ~10 x 15m has sunken by up to 2m into boiling hot pools, waterlevels ~2m below surface. Area has a long historical record of ground subsidence and is where a colleague got badly scalded in early 1970s when ground collapsed under him. At present a tourist footbridge spans part of this collapse and is main access to hot baths. Bridge is closed now and myself and an engineer have the job of deciding if any sort of bridge can be built to access the baths (and can they afford to build it?). I am very apprehensive about any on site and in ground geotechnical investigations and may decide it is too much risk to even do that.

Ashley Cody
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