New Underwater Fault Lines Discovered off New Zealand

Researchers recently completed a seismic survey around the coast of New Zealand. Nearly 200 underwater fault lines capable of causing devastating tsunamis were discovered. This has brought the total number of known active fault sources in the countries waters to 530. “We have to be prepared for these sorts of marine earthquakes in many New Zealand locations,” National Institute of Water and Atmospheric Research (NIWA) principal scientist Dr Philip Barnes said in a statement. The discoveries were attributed to the addition of newly identified offshore fault sources. Those include previously unknown faults in the bedrock under Pegasus Bay in the Canterbury region. On February 22 2011 an earthquake killed 185 people in the city of Christchurch. “There are many earthquake faults on the seafloor around our coasts, and the next major earthquake could be centered offshore. So it highlights the need for coastal marine investigations of active earthquake faulting, for both ground-shaking hazards and tsunamis,” said Barnes. Some significant changes in possible earthquake hazards were observed, he said. “If a major earthquake occurs on a seafloor fault, we might already have information about that fault,” said Barnes. In the last decade there have been tens of thousands of marine shakes, some easily felt and some hardly registering. Two of the most devastating earthquakes in the past 10 years were not so because of the shaking, but rather the tsunamis which came after. The 9.1 magnitude quake, which struck the northeast coast of Japan last year generated a massive wave with up to 40 meters of run-up height, Barnes said. Such a wave was not out of the realms of possibility here and the information for a number of regions had been updated with the latest finds. “We also now have some experience in how to respond and learn more about the cause of a major earthquake if such an event occurs. The more background information we have on active faults, the better.” Barnes would be presenting some of the information at the New Zealand Coastal Society Annual Conference.