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New Zealand's Alpine Fault Just Keeps Slipping

The fault has shifted approximately 700 kilometers over the past 25 million years

Snow line along the Southern Alps showcases New Zealand's Alpine Fault.

COURTESY OF JACQUES DESCLOITRES AND MODIS RAPID RESPONSE TEAM/NASA/GSFC

To feel the earth move under your feet, visit New Zealand. Every year the sides of the island nation's Alpine Fault shift past one another about 30 millimeters—a blistering speed for strike-slip faults, which typically slip at rates closer to one or two millimeters a year. “What is particularly interesting about the Alpine Fault is that it has maintained this high slip rate for almost its entire history,” says Simon Lamb, a geologist at the Victoria University of Wellington. “As far as I can tell, no other one land fault comes close in this respect.” In fact, the Alpine Fault has shifted approximately 700 kilometers over the past 25 million years—250 kilometers more than previously estimated, according to Lamb's new study in Geochemistry, Geophysics, Geosystems. That movement has seismic consequences: New Zealand has a 30 percent chance for an earthquake of magnitude eight or higher in the next 50 years.

 

FAULT NAME

LOCATION

LENGTH (km)

SLIP RATE (mm/yr)

Alpine

South Island, New Zealand

700

30

San Andreas

California

1,100

25

North Anatolian

Turkey

1,100

20

Denali

British Columbis to Central Alaska

2,000

10

Altyn Tagh

Tibet

1,500

9


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Top 5 Fastest-Moving Strike-Slip Faults

 

Scientific American Magazine Vol 314 Issue 6This article was originally published with the title “Fast Faults” in Scientific American Magazine Vol. 314 No. 6 (), p. 16
doi:10.1038/scientificamerican0616-16