Apr 9 2010 - March roundup

Survey activities on Ruapehu's Crater Lake during March.

Operations

• Three seismic sites, Aropaoanui (ARHZ), Te Karaka (TKGZ) and Waiomatatini Station (WMGZ), and one continuous GPS Site Waiomatatini (WMAT) were completed in the Hawke's Bay and Gisborne regions.
• One seismic site Whakapapataringa (WPRZ) was completed north of Taupo.
• Two boreholes were drilled for seismic sensors on Mount Taranaki for North Egmont (NEZ, to 111 m depth) and on Mount Ruapehu for Wahianoa (WNVZ, to 52 m depth).
• Communication links were upgraded to 4 continuous GPS sites in the South Island to improve the 1 second data streaming performance.

Earthquakes

• The most widely-felt earthquake of the month occurred on March 3, magnitude 3.1, 10 km north-west of Takaka at a shallow depth of 10 km. 53 felt earthquake reports were received.
• The preliminary locations of February's earthquakes are shown below.

Volcano Surveillance

Tuesday March 2 - Spring and fumarole sampling at White Island

Three fumaroles were sampled, and temperatures and flows hadn’t changed much since the November 2009 sampling trip. Springs, streams and Crater Lake were sampled and again temperatures were close to the November observations. Cindy’s Mistake Pool was the only site to have increased, up by 5 degrees. The Crater Lake level also appeared similar to the level observed in November. Flows of several features were measured or estimated and were not significantly different to the November measurements. There was a lot of discoloured water at the eastern slip site, as well as on the western side of the island.

Friday March 5 - Ruapehu sampling trip

Ruapehu Crater Lake was sampled in conjunction with the deployment of a meteorological buoy. Both vents were sampled, unusually from an inflatable boat, with the temperature measured at 23.8 °C in both places. Sonar measurements were made across the lake, as well as some spot CO₂ measurements in the vent areas. The weather buoy will be operating during the next 4 to 6 weeks, sending data to a datalogger at the lake outlet. Flow at the outlet was measured at 90L/sec.

Reported Landslides

Sunday March 21

• Heavy rain in Fiordland caused flooding and slips, trapping more than 120 trampers on the Milford Track. Two significant landslides blocked the Milford Road.

Wednesday March 31 (approximately)

• A landslide near Potted Head (near the north tip of Taukihepa/Big South Cape Island of the Titi/Muttonbird Island group off Stewart Island) demolished or severely damaged several of a group of half a dozen buildings including sheds and baches (none of which were occupied at the time, but were regularly used). Another house at the south end of the island was reported to have been damaged by a slip in the same rainstorm event.

Felt earthquakes of February 2010.

Shallow earthquakes of February 2010.

Deep earthquakes of February 2010.