New Zealand Earthquakes

Abstract

DURING March 1943, fifteen strong earthquakes were registered by the seismographs at Auckland, Arapuni, Bunnythorpe, Christchurch, Kaimata, New Plymouth, Tuai and Wellington, all stations participating in the New Zealand Seismological Service and sending records or readings to the Dominion Observatory at Wellington (New Zealand Seismological Report-Provisional Bulletin, No. P 133, 1943, March). The records are remarkable in that eight of the shocks had a depth of focus greater than normal. The first, on March 4, had an epicentre south of Fiji and a depth of focus near 600 km. The shock of March 11 with epicentre east of New Caledonia had a depth of focus near 100 km. Earthquakes on March 15 and 21 have already been reported in NATURE, the data coming from, the U.S. Coast and Geodetic Survey. On March 26 a very strong earthquake with an epicentre south-east of Tonga had a focal depth of between 80 and 100 km. It was reported to have been felt at Nukualofs, according to a message from Apia. The earthquake gave very large amplitudes on the vertical components of seismographs. Further, there was minor seismic activity, and 22 earthquakes or earth tremors were reported as having been felt (additionally) in New Zealand. The greatest of these shocks was Scale VI on the Modified Mercalli Scale. It occurred on March 14 and was felt in the southern part of South Island. Two earthquakes were felt with Scale V intensity. The first, on March 1, was felt from Te Kuiti and Waipawa to Greymouth and Rakaia. The second, on March 25, was felt at Westport. One shock was felt with Scale IV intensity and the rest with lesser intensities.