Uniformity of vertical faulting for the last 7000 years at Lake Poukawa, Hawke's Bay, New Zealand

Abstract

Rates of fault movement are commonly assumed to be uniform. Analysis of the progressive increase in offset, by the Wairarapa Fault, of dated tephras within peat at Lake Poukawa, shows this to be true. A uniform vertical faulting rate of 0.2 mm/year is determined.

Age of each offset of the fault is estimated giving a recurrence time of 800-900 years. The constant rate of faulting indicates that the next major earthquake affecting the fault at Poukawa will be in no more than 500 years time. This does not, however, exclude the possibility of other earthquakes in this region.

Keywords:

• faults
• Wairarapa Fault
• Hawke's Bay
• rates
• tephras
• stratigraphy
• earthquakes