Timing of late Holocene paleoearthquakes on the Hurunui segment of the Hope fault: Implications for plate boundary strain release through South Island, New Zealand

Abstract

The Hurunui segment of the dextral-slip Hope fault extends for ~42 km between the Hope and Hurunui River catchments and westward to Harper Pass at the Main Divide of South Island. We conducted paleo seismic, soil, and landscape dating studies in the upper Hurunui valley to determine the timing of past earthquake ruptures along this geometric fault segment. On a late Holo cene alluvial surface at Matagouri Flat, a young channel system is displaced dextrally by ~4.5 ± 0.6 m, which is attributed to the most recent faulting event. A trench and soil pits excavated nearby yield evidence for the timing of the last two surface-faulting events. These events, dated from a combination of radiocarbon dates, relative soil, tree, and historical constraints, modifi ed within an OxCal analysis, occurred at ca. A.D. 1655-1835 and 1425-1625. The occurrence of two rupture events during the last ~600 yr is consistent with previous estimates stating a short recurrence interval for the Hurunui segment. The most recent faulting event in our trenches predates the historic 1888 North Canterbury (Amuri) earthquake, which ruptured the Hope River segment to the east. A comparison of the record from the Hurunui segment with paleoseismic records from other segments along the Hope fault zone indicates evidence for two or three rupture events within the last 700-900 yr. Within the age resolution of the current dates, the data suggest that along-strike rupture occurred along the majority of the Hope fault zone between 120 and 360 yr ago (i. e., A.D. 1650-1888), and may all postdate the most recent rupture of the Alpine fault in ca. A.D. 1717. In addition, the timings of penultimate faulting events along the Hurunui, Hope River, and Conway segments and the Hanmer fault all fall in the range ~400-700 yr ago. These preliminary observations indicate that rupture of segments of the Hope fault, and indeed the Alpine fault, could occur as clusters that are years to decades apart. Rupture of the major plate boundary faults in the northern South Island may therefore occur in sequences that are enhanced, or even retarded, by stress triggering and fault interactions.

Recovering paleoearthquake slip record in a highly dynamic alluvial and tectonic region (Hope Fault, New Zealand) from airborne lidar

“…These two prehistorical earthquakes might have produced the two smallest cumulative slips that we measured, at 4.2 ± 1.2 m and 9.0 ± 1.0 m (their coseismic slip would thus have been ~4.2 and ~4.8 m, respectively, in agreement with prior suggestions). Much of the Hope Fault failed in at least one or two large earthquakes in the time range of 400–700 years. Although the slips produced by these older paleoearthquakes are not well constrained, amounts up to 5–6 m have been suggested [e.g., Langridge et al , , and references therein]. These one or two large earthquakes might have combined to produce the cumulative slips that we measured at 14.2 ± 1.2 m and 18.0 ± 1.0 m (their coseismic slip would thus have been ~5.2 and ~3.8 m, respectively, in agreement with prior suggestions).…”

“…Small lateral offsets supposed to record the most recent earthquakes are particularly few, with only 10 measured offsets lower than ~60 m. From these few measurements, it has been inferred that the most recent large earthquake on the eastern Hope Fault produced a lateral slip at surface in the 3 to 6 m range [ Knuepfer , ; Pope , ; Langridge et al , ]. Meanwhile, the synthesis of the numerous trench results suggests that 2–3 large paleoearthquakes broke separately the western and the eastern Hope Fault, at two similar periods, 700–400 and 360–120 year ago [ Langridge et al , , and references therein].…”

“…Therefore, in such a context of high alluvial and tectonic dynamics, it is not clear whether the geomorphic records can be used to recover the earthquake slip history. Field measurements available on the Hope Fault prove that some paleoseismological information is preserved in the morphology [e.g., Cowan and McGlone , ; Yang , ; Knuepfer , ; Langridge et al , , ; Langridge and Berryman , ], but these measurements are too few (i.e., 10 offsets < 60 m on eastern Hope Fault that we analyze; see section 2) to discriminate confidently the paleoearthquakes and to determine the slips they produced all along the fault.…”

Imaging the 2016 Mw 7.8 Kaikoura, New Zealand, earthquake with teleseismic P waves: A cascading rupture across multiple faults

“…On 13 November 2016 at 11:02:56 UTC an M w 7.8 earthquake (GEONET, 42.693°S, 173.022°E, 15 km) struck the Marlborough Fault System (MFS) of South Island, New Zealand, near the town of Kaikoura. The dextral strike‐slip MFS comprises the Hope Fault, the Clarence Fault, the Awatere Fault, and the Wairau Fault [ Langridge et al ., ] and links two oppositely verging subduction zones—the Puysegur and Hikurangi (Figure ). In view of the southwest‐northeast strike of the MFS, the nodal plane with strike 226°, dip 33°, and rake 143° from the global centroid moment tensor (gCMT, 2016, Global centroid moment tensor Web page, Columbia University, http://www.globalcmt.org/CMTsearch.html, last accessed 26 December 2016) likely represents the fault plane.…”

Liquefaction Features Produced by the 2010–2011 Canterbury Earthquake Sequence in Southwest Christchurch, New Zealand, and Preliminary Assessment of Paleoliquefaction Features

“…Timing of major historic earthquakes, prehistoric fault ruptures, and large landslides in the wider region. Timing information from subduction zone, Clark et al (2015); Alpine fault, Berryman et al (1992), Berryman, Cochran, et al (2012), Berryman, Cooper, et al (2012), and Howarth et al (2012Howarth et al ( , 2014; Hope fault, Conway segment, Langridge et al (2003); Hope fault, Hope River segment, Cowan and McGlone (1991); Hope fault, Hurunui segment, Langridge et al (2013) and Khajavi et al (see Data and Resources); Poulter fault, Berryman and Villamor (2004); Acheron rock avalanche, Smith et al (2006); Porters Pass fault, Howard et al (2005); Ashley fault, Sisson et al (2001); Moncks Cave, Jacomb (2008Jacomb ( , 2009. Location information for all faults from Litchfield et al (2014) and references therein.…”