Aftershocks Near White Island

Eighty distinct aftershocks have been recorded since yesterday’s earthquake near White Island volcano.

A very shallow magnitude 5.4 earthquake struck 10 km south-west of White Island at 9:06 yesterday morning, Friday the 13th of June 2008. The undersea quake was only 5 km deep and volcanologists report that it was a result of tectonic processes, and not caused by volcanic activity.

The earthquake has been followed by 80 distinct aftershocks in the period to midday today, Saturday, when the GeoNet database was last updated. Eight of the shocks have been of magnitude 4, and 31 of magnitude 3. The balance, 41 events, were of 2nd magnitude.

Most of the aftershocks have been very shallow, with 59 events at depths of 5 km or less. All have struck within a 20 km radius of the volcano. The largest aftershock was a magnitude 4.3 quake at 7:35 p.m. last night.

Despite being shallow, the magnitude of the main event was unlikely to have generated a tsunami wave, and tsunami gauges at Gisborne, Napier, Wellington and Chatham Island do not show any appreciable variation from normal sea levels during the 30 hours since the quake struck.

[Compiled from data provided by the GeoNet project and its sponsors EQC, GNS Science and FRST.]

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