Evidence of two quakes extends rupture history in Grand Tetons National Park

phys.org | 4/5/2019 | Staff
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Hand-dug trenches around Leigh Lake in Grand Teton National Park in Wyoming reveal evidence for a previously unknown surface-faulting earthquake in along the Teton Fault—one occurring about 10,000 years ago.

Together with evidence from the site of a second earthquake that ruptured around 5,900 years ago, the findings published in the Bulletin of the Seismological Society of America extend the history of Teton Fault earthquakes and may offer some clues as to how segments of the fault have ruptured together in the past, the study authors suggest.

Teton - Fault - Faults - United - States

The Teton Fault is one of the fastest-moving normal faults in the western United States, separating the eastern edge of the Teton Range from the Jackson Hole basin. The fault is divided into southern, central and northern segments, with the Leigh Lake site falling within the central segment. A previous study identified two Teton Fault earthquakes that occurred 8,000 years ago and 4,700 to 7,900 years ago on the southern segment at Granite Canyon, one of the most famous hiking spots in the Grand Teton National Park.

The younger earthquake at Leigh Lake may be the same rupture as the youngest Granite Canyon earthquake, confirming that there were at least three earthquakes in Holocene times, and that the most recent activity along the fault occurred about 6,000 years ago, said Mark Zellman of BGC Engineering, Inc., the lead author of the BSSA study.

Leigh - Lake - Study - Answer - Question

Although the Leigh Lake study doesn't provide a definite answer to the question of whether multiple segments of the Teton fault have ruptured at once, Zellman said the findings "do give us a clue that multi-section ruptures are possible. The overlap in age between the youngest Leigh Lake earthquake and the youngest Granite Canyon earthquake "leaves open the possibility that at least the southern and central section of the Teton fault ruptured together during...
(Excerpt) Read more at: phys.org
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