South Island, New Zealand, and transverse ranges, California: A seismotectonic comparison

Abstract

Both the South Island of New Zealand and the Transverse Ranges of California have (1) a major right‐slip fault marking the plate boundary, (2) a left‐stepping bend in the fault resulting in ranges and basins bounded by active reverse faults that strike 45° counterclockwise to the regional strike of the main fault, (3) a set of right‐slip faults on one side of the constraining bend, with most of the total displacement concentrated On the fault stepped farthest left from the continuation of the fault on the other side of the bend, and (4) intersections between the set of faults and the main fault within the bend not present or poorly defined. The faults with most of the displacement (Alpine‐Wairau, San Andreas) may pre‐date the constraining bend, The reverse fault province southeast of the Alpine fault is separated from that fault by the Southern Alps, which may be underlain by crust that is too hot and too weak to sustain major reverse faults. Average reverse fault recurrence intervals in New Zealand and California are 10³ to 2 × 104 years as compared to less than 10³ years for the right‐slip master fault, Seismicity is high but patchy in the Nelson‐Buller region of the northern South Island, low but patchy in the Transverse Ranges, and very low in Central Otago in the southern South Island, all reverse fault provinces. Seismicity patterns in both regions, poorly related to overall late Quaternary fault distribution, correspond largely to individual rupture events on portions of Quaternary faults, and the seismic inactivity of many of these faults may simply represent quiescence between seismic faulting with long recurrence intervals. The geology and Seismicity of the three reverse‐fault provinces support the suggestion of C. R. Allen [1975] that late Quaternary fault history is a better long‐term guide for assessment of large‐magnitude earthquake hazard than instrumental and historical Seismicity for faults with long recurrence intervals.

The kinematics of a transition from subduction to strike‐slip: An example from the central New Zealand plate boundary

“…As pointed out by McCaffrey et al [2007] the transition from subduction to strike‐slip in central New Zealand bears many similarities to the transition from the North America/Pacific strike‐slip plate boundary in California to subduction of the Gorda and Juan de Fuca Plates at the Cascadia margin offshore Oregon (note this is a triple junction type transition, Figure 10a). In California, North America‐Pacific relative plate motion is nearly parallel to structures there and the majority of this is accommodated as strike‐slip along the San Andreas Fault System, which is analogous to the Marlborough Fault System [ Yeats and Berryman , 1987] and the Alpine Fault in the South Island. The contemporary vertical‐axis rotation rates of crustal blocks in California as determined from GPS are similar to the Pacific Plate [ McCaffrey , 2005], mirroring what we observe in most of the South Island [ Wallace et al , 2007].…”

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

“…1) (e.g., Yeats and Berryman, 1987;Berryman and Beanland, 1991;Wallace et al, 2007). Between the dextral-reverse Alpine fault in the central South Island and the Hikurangi subduction zone offshore of the North Island, the Australia-Pacifi c plate boundary is characterized by a zone of distributed strike-slip to oblique-slip faulting (e.g., Van Dissen and Yeats, 1991;Berry man et al, 1992;Nicol and Van Dissen , 2002;Pondard and Barnes, 2010).…”

The 1968 Inangahua, New Zealand, and 1994 Northridge, California, earthquakes: Implications for northwest Nelson

“…Northwest Nelson is analogous to the California Transverse Ranges in being a reverse-fault province lying oblique to a plate-boundary strike-slip fault (Yeats & Berryman 1987). Its historical seismicity, including the 1929 and 1968 earthquakes, as well as poorly understood earthquakes in 1868 and 1893 (Anderson et al 1994), are reminiscent of the high historical seismicity in the Transverse Ranges.…”

“…Northwest Nelson, New Zealand, is characterised by northtrending ranges and basins flanked by reverse faults (Yeats & Berryman 1987). The region was shaken by two large reverse-fault earthquakes in the 20th century: the 16 June 1929 Murchison earthquake of M7.7 and the 23 May 1968 Inangahua earthquake of M7.2.…”