Abstract - Paleoearthquakes at the Earth’s surface often generate variable fault displacement rates. The origin of these variations and the extent to which they result from systematic processes is unresolved. To address this question we use geomorphic and trench data to investigate the source of displacement rate fluctuations over 60 thousand years for normal faults in the Taupo Rift, New Zealand. We find that the stability of displacement rates is related to fault size, with aggregated displacement rates across the entire rift being uniform over time intervals of at least 60 thousand years. This relation suggests that each fault is a component of a kinematically coherent system in which all faults interact and their earthquake histories are interdependent. Fault interdependencies generate both short term (<18 kyr) fluctuations in, and longer term (>18 kyr) stability of, displacement rates.
Abstract of talk given to:
Irish Geological Research Meeting, Trinity College Dublin, February 2005.