Time Kinematic Global Navigation Satellite System (RTK GNSS) and tape- .... Uplift along the KaikÅura coastline has also been calculated from point ... post-earthquake centre line of roads was used to estimate uplift. North and south of the KaikÅura. Peninsula, State Highway 1 (SH-1) lies along a coastal strip and was ...
DATA REPOSITORY Auxiliary Material Submission for paper: Breaking a subduction-termination from top to bottom: the large 2016 Kaikōura Earthquake Vasiliki Mouslopoulou1,4*, Vasso Saltogianni1, Andrew Nicol2, Onno Oncken1, John Begg3, Andrey Babeyko1, Simone Cesca1, Marcos Moreno1,5 1
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Deutsches GeoForschungsZentrum GFZ, Telegrafenberg, Potsdam, 14473, Germany
Department of Geological Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand 3
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GNS Science, PO Box 30-368, Lower Hutt, New Zealand
National Observatory of Athens, Institute of Geodynamics, Athens, 11810, Greece
Departamento de Geofísica, Facultad de Ciencias Físicas y Matemáticas, Universidad de Concepción, Concepción, Chile *Corresponding author
The following text and data (Supplementary Figs. S1-S17 and Supplementary Tables S1-S6) present details on the marine-biota measurements, Lidar differencing, earthquake relocation, dislocation modeling, modeling of post-seismic deformation, Coulomb-stress modeling and tsunami simulations, complementing those included in the article: ‘Breaking a subductiontermination from top to bottom: the large 2016 Kaikōura Earthquake’. 1. Marine biota uplift measurements Vertical displacements have been measured globally using inter-tidal marine biota on rocky coastlines, often providing important constraints for incremental uplift during large-magnitude earthquakes and cumulative geological uplift (Pirazzoli et al., 1982; Stiros et al., 1992; Clark et al., 2011; Mouslopoulou et al., 2015). Biological records of coseismic uplift were collected using the elevation of 1509 stranded algal holdfasts during a ten-day period (January 30th till February 1
9th, 2017), approximately two and a half months after the Kaikōura Earthquake (Supplementary Table S1). The rocky shores around Kaikōura are associated with three major tidal zones: a) an upper belt of littorinid gastropods (e.g., Littorina unifasciata and L. cincta) and barnacles (e.g., Epopella plicata); b) a mid-tidal region dominated by grazing molluscs (e.g., Cellana denticulata, Melagraphia aethiops and Turbo smaragdus); and c) a lower zone of brown algae (e.g., Durvillaea antarctica and Carpophyllum maschalocarpum) (Marsden, 1985). In this study the brown algae Durvillaea and Carpophyllum are utilised to measure coastal uplift. Around the Kaikōura Peninsula and north Canterbury coast, holdfasts of Durvillaea antarctica and D. willana (Supplementary Fig. S1), are anchored to coralline encrusted rocky surfaces. As during our fieldwork decay of attached and uplifted biota was well advanced, our primary target species were restricted to holdfast stumps of Durvillaea or Carpophyllum with brittle fronds attached (Supplementary Fig. S1). At all localities uplift was apparent from the exposure and subsequent degradation of intertidal biota, and algal holdfasts were exposed above the waterline, and measurements were collected on rising or falling mid- and low-tides. Holdfasts were preferentially measured on rock faces sheltered from, but retaining connection to, the open sea, to minimise error introduction by the potentially higher tidal position of Durvillaea in wave-washed sites. Each site was visually assessed to establish the upper extent of holdfasts, and the uppermost holdfasts were measured (as they will be closest to the pre-earthquake upper limit of each species). In sites with boulders rather than bedrock exposure, only boulders that showed a portion of their surface to have been clearly within the pre-earthquake mid- or upper-tidal zone (evidenced by bare or barnacle encrusted surfaces) were selected for measurement, therefore ensuring the upper limit of holdfasts were represented. Two different methodologies were used to measure the vertically displaced biota: Real Time Kinematic Global Navigation Satellite System (RTK GNSS) and tape-measurements (Supplementary Figs. S1-S2). Regarding the former, at each site the water-level was measured in the most sheltered area available to minimise wave effects, and the time the measurement was collected was recorded. Following measurement of the waterline up to twenty holdfasts (either or both Carpophyllum and Durvillaea) were measured within close proximity. This RTK collection method did not require the waterline measurement site, and the holdfasts, to be immediately adjacent to each other. Additional biological data were collected using a tape-measure (Supplementary Fig. S1). Tape measurements were collected between the waterline (measured between wavelet peaks and troughs) and the uppermost algal holdfasts on rock surfaces. Sheltered faces were again preferentially measured. Each reading for both (RTK or tape) was annotated with the alga measured and relative site exposure (exposed or sheltered) and time of measurement recorded. The field measurements of apparent uplift were further processed to determine total co-seismic uplift, taking into account the time of data measurement and the preearthquake living position of algal holdfasts. Collectively, 1509 field measurements of marine biota were obtained along > 40 km of coastline using tape-measure and RTK-GPS equipment (Supplementary Table S1). All measurements are presented in Supplementary Table S1. In 2
addition to the uplift measurements included in Table S1, the coastal profile illustrated in Figure 1c includes also uplift marine-biota measurements for the northern domain of the rupture from Clark et al. (2017).
Supplementary Figure S1: Collecting field measurements from uplifted paleoshorelines near the Kaikōura Peninsula. Our preferred marine biota was the intertidal kelp ‘Carpophyllum’, a species endemic to New Zealand that is only present in the low intertidal zone, where it forms a distinct band at low water (see dashed red line), and is not exposed at low spring tides.
Supplementary Figure S2: Collecting uplift measurements using RTK proximal to the Kaikōura tidegauge (in the background). 3
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Locality North of Half Moon Bay South Half Moon Bay Nins Bin South Nins Bin Hapuku River Kaikoura tide gauge Kean Point Kaikoura north neck Kaikoura Peninsula Lodge Kaikoura Peninsula Center Atia Point North Atia point East Atia point South Kaikoura Side side 1 Kaikoura Harbour South side 3 Kaikoura south neck Peketa South Pinacle rock BR (Barney's rock) Panau Island (PI) Kiki point (KP) Paia point Goose Bay1 Otumatu Rock1 Omihi Point Karakanui Hundalee Fault North Hundalee Fault down Hundalee down 1 (HFD) Oaro Oaro south Forest chick Haumuri bluff
Latitude 42°15'11.73"S 42°15'39.58"S 42°16'5.72"S 42°16'50.40"S 42°19'36.83"S 42°24'47.29"S 42°25'25.88"S 42°24'16.02"S 42°25'16.18"S 42°25'48.76"S 42°25'59.36"S 42°26'5.97"S 42°26'11.96"S 42°25'37.63"S 42°25'35.39"S 42°25'8.57"S 42°24'50.22"S 42°26'11.99"S 42°26'36.41"S 42°26'59.95"S 42°27'32.19"S 42°27'47.12"S 42°28'20.21"S 42°28'59.37"S 42°29'3.20"S 42°29'22.06"S 42°29'50.20"S 42°30'4.00"S 42°30'16.22"S 42°30'18.23"S 42°30'56.70"S 42°31'21.58"S 42°32'3.63"S 42°33'51.80"S
Longtitude 173°49'3.65"E 173°48'42.98"E 173°48'7.68"E 173°47'3.53"E 173°44'27.59"E 173°42'11.54"E 173°43'6.52"E 173°41'5.71"E 173°42'32.77"E 173°42'23.79"E 173°41'26.13"E 173°41'31.70"E 173°41'28.25"E 173°41'12.64"E 173°40'55.73"E 173°40'40.51"E 173°40'10.17"E 173°35'17.95"E 173°35'10.22"E 173°34'28.68"E 173°33'24.50"E 173°32'41.59"E 173°32'11.83"E 173°31'44.68"E 173°31'49.13"E 173°31'28.33"E 173°31'13.41"E 173°30'55.71"E 173°30'41.25"E 173°30'37.15"E 173°30'26.96"E 173°30'16.08"E 173°30'11.78"E 173°30'24.42"E
Number of observations 48 15 41 25 nick point 196* 141* 48 20 30 20 42 94* 15 48 15 20 33 28* 56* 31* 40* 109* 76* 35* 41* 43 66* 60* 4 18* 4 45* 1
Total uplift (cm) 290,9 178,8 184,6 128,5 70 98,8 82,3 104,2 72,1 88,2 74,1 82,1 70,3 68,5 68,4 68,5 67,7 11,3 34,4 37,7 67,9 101,5 125,3 171,6 176,2 159,9 163,9 164,0 69,9 62,8 8,5 34,1 14,8 0
Error (cm) 45,1 23,4 46,5 27,3 10 10,3 13,7 11,8 5,7 12,1 7,5 13,5 14,1 6,3 10,4 15,1 19,3 22,8 2,9 7,1 12 13,3 12,9 22,1 12,9 21,3 14,9 15,8 26,5 4,5 4,2 2,1 14,8 -
Supplementary Table S1: Table presenting the localities, the number of observations per locality and the total co-seismic uplift (with associated uncertainties) calculated from marine-biota collected during our field survey in early 2017. All measurements are collected with tape-measure except those indicated by asterisk (*) which is the average of uplift-measurements collected with RTK and tape-measure.
Date of survey 5 Feb 2017 5 Feb 2017 5 Feb 2017 5 Feb 2017 6 Feb 2017 2 Feb 2017 5 Feb 2017 4 Feb 2017 9 Feb 2017 9 Feb 2017 4 Feb 2017 4 Feb 2017 4 Feb 2017 4 Feb 2017 4 Feb 2017 4 Feb 2017 4 Feb 2017 6 Feb 2017 1 Feb 2017 31 Jan 2017 31 Jan 2017 31 Jan 2017 2 Feb 2017 31 Jan 2017 1 Feb 2017 1 Feb 2017 6 Feb 2017 1 Feb 2017 1 Feb 2017 1 Feb 2017 2 Feb 2017 2 Feb 2017 2 Feb 2017 2 Feb 2017
2. Lidar differencing Uplift along the Kaikōura coastline has also been calculated from point elevation difference using two suites of LiDAR, one pre-earthquake data, the other post-earthquake. Pre-earthquake LiDAR data were collected on 17th-18th February 2012 by Aerial Surveys for Environment Canterbury and post-earthquake data was collected by AAM on 19th-21st November 2016 for NZ Transport Agency. LiDAR point clouds were gridded to generate digital elevation models for each LiDAR data suite. To minimise any impact of gravity induced slope failures and horizontal tectonic displacement during the earthquake the difference of the elevation of individual points along the post-earthquake centre line of roads was used to estimate uplift. North and south of the Kaikōura Peninsula, State Highway 1 (SH-1) lies along a coastal strip and was constructed to a high standard as the main road link between Christchurch and the north of the South Island. In general, slopes on the road are gentle and cambers are present only at corners and reflect the speed limit of 100 km/hr. The centre line of the two-lane highway has low relief (e.g.,
