Earthquakes at Mt. Ngauruhoe

Shallow earthquake activity on the northern flank of Ngauruhoe volcano, which began in May 2006, has increased.

The northern flank of Mt. Ngauruhoe in the central North Island has been experiencing shallow volcanic earthquake activity since May 2006. Between 5 and 30 quakes have been recorded each day at a depth of about 1 km with the largest about magnitude 1.5.

On January 6th the earthquake rate began increasing, reaching up to 80 per day on the 9th and 10th. The larger events have been between magnitude 1.2 and 1.5, with the rate decreasing slightly since.

In an Alert Bulletin released yesterday afternoon (Friday), Brad Scott, Duty Volcanologist for GNS Science advised that scientists visited the volcano to take appropriate measurements and found that volcanic gas concentrations, temperatures and soil gas flux measured at the summit have not changed since readings taken in May 2006, and are similar to measurements taken in the intervening period.

Three additional seismographs have been installed to study the earthquake activity.

The Alert Bulletin from GNS Science, issued at 2 p.m., stated that no other unrest has been recorded at Mt. Ngauruhoe, and there is no evidence that an eruption is imminent.

GeoNet reported two stronger and slightly deeper earthquakes three minutes apart in the area later in the afternoon. The earthquakes struck 20 km south-west of Turangi (60 km south-west of Taupo) at 4:49 and 4:52 p.m. yesterday, Friday 18th January 2008. The magnitude 3.1 and 3.7 events were at depths of 4 km.

[source: GNS Science Alert Bulletin issued 18th January 2008 at 2.00 p.m; and data supplied by the GeoNet project and its sponsors EQC, GNS Science and FRST.]

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