Late Pleistocene fault slip rate, earthquake recurrence, and recency of slip along the Pyramid Lake fault zone, northern Walker Lane, United States

Abstract

Up to 25% of Pacific-North America plate relative transform motion is accommodated east of the Sierra Nevada. Most of that 25% is taken up by deformation in the Walker Lane, a discontinuous zone of strike-slip and normal faults approximately parallel to the San Andreas. The Pyramid Lake fault zone is a northwest trending right-lateral fault in the northern Walker Lane, Nevada. Recent geodetic surveys report 6 ± 2 mm/year of right-lateral shear strain accumulation across the northern Walker Lane. Interpretation of displaced geomorphic features preserved in post-Lake Lahontan (∼15,500 cal. yr B.P.) surfaces indicate the Pyramid Lake fault zone has accommodated at least 2.6 ± 0.3 mm /year of right-lateral shear during the late Pleistocene. Additionally, a minimum of two earthquakes have occurred since deposition of the Mazama tephra (∼7630 cal. yr B.P.), and at least four earthquakes have occurred on the fault after desiccation of Lake Lahontan (∼15.5 ka), with the most recent earthquake occurring after 1705 ± 175 cal. yr B.P. The observations indicate that the Pyramid Lake fault zone accommodates the major portion (≥25%-70%) of right-lateral slip east of the Sierra Nevada at the latitude of ∼39°45′N. Copyright 2004 by the American Geophysical Union.