Tectonic Ping-Pong

A series of earthquakes struck the tectonic plate boundaries near New Zealand this morning, with several events in the southern Kermadecs, upper South Island and off the Fiordland coast.

The sequence began with a magnitude 4.9 earthquake located 100 km west of L’Esperance Rock (305 km south-west of Raoul Island) in the Kermadec Islands at 4:15 a.m. on Monday 21st January 2008. The quake was 342 km deep.

A magnitude 3.4 quake located 10 km north-east of Hanmer Springs followed several hours later. The 6:47 a.m. quake was only 7 km deep and was felt locally.

The largest event was a magnitude 5.3 earthquake located off-shore 80 km west of Milford Sound at 7:41 a.m. This 20 km deep quake was widely felt in South Canterbury, Otago, Southland and Fiordland. By 10:30 this morning, 113 felt reports had been lodged with the GeoNet site, indicating that the quake was strongly felt at Riverton and Te Anau, and one report of substantial damage was lodged from Te Anau.

Activity off the Fiordland coast continues, with a magnitude 3.9 quake at 8:56 a.m., a magnitude 4.1 quake at 9:14, a magnitude 3.5 at 9:35 and an interesting pair of events 12 seconds apart at 9:56 a.m. The first event was a magnitude 4.8 quake further offshore to the west at the greater depth of 81 km. The second of the pair was magnitude 4.6 quake at the same location as the other events, and at a similarly shallow depth of 17 km.

[Compiled from data provided by the Geonet project and its sponsors EQC, GNS Science and FRST; and the US Geological Survey and its contributing agencies.]

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