New Zealand is racing against the clock to make itself ready for a potentially massive earthquake along the country’s Alpine Fault. This fault, located along the country’s South Island, has a history of sudden movements. Scientists believe that the country is due for a large-scale earthquake and are working together to prepare themselves for the inevitable.
The Alpine Fault is an 850-kilometer geological fault that runs along the mountainous spine of the South Island, physically marking where the Australian and Pacific plates meet and grind against each other, which in turn forms the Southern Alps.
A new study published in April 2021 puts the probability of an earthquake on the central section of the fault at 75% in the next 50 years. This is a massive jump in percentage as previous studies placed the probability of an earthquake around 29%. Scientists believe that such an earthquake will be of magnitude 8 or higher.
The team of researchers from Victoria University of Wellington, the University of Otago, GNS Science, the University of California, and the United States Geological Survey studied evidence of 20 previous Alpine Fault earthquakes over a 4000-year period.
The evidence was recorded in the sediment of four West Coast lakes (Lakes Kaniere, Mapourika, Paringa, and Ellery) and two swamps. The results of this study were some of the most complete earthquake records of its kind in the world.
To obtain their data, the research team drilled down six meters and extracted a cross-section of the lake bed, which revealed a literal line-by-line snapshot of its history.
The strong shaking during earthquakes deformed layers of sediment, causing them to collapse and blend together. The vibration also weakened material at the edge of the lake, which caused underwater landslides.