Ground motions observed in the Darfield and Christchurch earthquakes and the importance of local site response effects

Bradley, B.

doi:10.1080/00288306.2012.674049

Cited by 31 publications

(15 citation statements)

References 7 publications

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“…High-frequency data show complex velocity and displacement paths for any given site. The variations across the sites are significant, as reported previously (Van Houtte et al, 2012;Bradley, 2016). At the same site (LPCC, Fig.…”

Section: Strong Ground Motion Datasupporting

confidence: 86%

“…For instance, LPCC station located ∼ 6 km from D13C recorded 0.3 and 0.9 g PGA following the M w = 7.1 and M w = 6.2 events respectively (Bradley and Cubrinovski, 2011). Moreover, extrapolation of PGA contours of Bradley (2012) suggests that D13C and Rapaki sites experienced PGAs exceeding 0.25 and 0.45 g during M w = 7.1 and M w = 6.2 earthquakes respectively. Some of the rockfall sites investigated herein might have had reached a critical failure threshold prior to being triggered by the 13 June 2011 M w = 6 earthquake.…”

Section: Interpretations Of Strong Ground Motion Datamentioning

confidence: 98%

See 1 more Smart Citation

Geologic and geomorphic controls on rockfall hazard: how well do past rockfalls predict future distributions?

Borella

Quigley

Krauss

et al. 2019

Nat. Hazards Earth Syst. Sci.

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Abstract. To evaluate the geospatial hazard relationships between recent (contemporary) rockfalls and their prehistoric predecessors, we compare the locations, physical characteristics, and lithologies of rockfall boulders deposited during the 2010–2011 Canterbury earthquake sequence (CES) (n=185) with those deposited prior to the CES (n=1093). Population ratios of pre-CES to CES boulders at two study sites vary spatially from ∼5:1 to 8.5:1. This is interpreted to reflect (i) variations in CES rockfall flux due to intra- and inter-event spatial differences in ground motions (e.g., directionality) and associated variations in source cliff responses; (ii) possible variations in the triggering mechanism(s), frequency, flux, record duration, boulder size distributions, and post-depositional mobilization of pre-CES rockfalls relative to CES rockfalls; and (iii) geological variations in the source cliffs of CES and pre-CES rockfalls. On interfluves, CES boulders traveled approximately 100 to 250 m further downslope than prehistoric (pre-CES) boulders. This is interpreted to reflect reduced resistance to CES rockfall transport due to preceding anthropogenic hillslope de-vegetation. Volcanic breccia boulders are more dimensionally equant and rounded, are larger, and traveled further downslope than coherent lava boulders, illustrating clear geological control on rockfall hazard. In valley bottoms, the furthest-traveled pre-CES boulders are situated further downslope than CES boulders due to (i) remobilization of pre-CES boulders by post-depositional processes such as debris flows and (ii) reduction of CES boulder velocities and travel distances by collisional impacts with pre-CES boulders. A considered earth-systems approach is required when using preserved distributions of rockfall deposits to predict the severity and extents of future rockfall events.

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Section: Strong Ground Motion Datasupporting

confidence: 86%

Section: Interpretations Of Strong Ground Motion Datamentioning

confidence: 98%

Geologic and geomorphic controls on rockfall hazard: how well do past rockfalls predict future distributions?

Borella

Quigley

Krauss

et al. 2019

Nat. Hazards Earth Syst. Sci.

View full text Add to dashboard Cite

show abstract

“…Moreover, extrapolation of PGA contours of Bradley (2012) suggests that D13C and Rapaki sites experienced PGA exceeding 0.25g and 0.45g during Mw 7.1 and Mw 6.2 earthquakes respectively. Some of the rockfall sites investigated herein might have had reached a critical failure threshold prior to being triggered by the 2011-06-13 Mw 6 earthquake.…”

Section: Interpretations Of Strong Ground Motion Datamentioning

confidence: 94%

Geologic and geomorphic controls on rockfall hazard: how well do past rockfalls predict future distributions?

Borella¹,

Quigley²,

Krauss³

et al. 2019

Preprint

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Abstract. To evaluate the geospatial hazard relationships between recent (contemporary) rockfalls and their prehistoric predecessors, we compare the locations, physical characteristics, and lithologies of rockfall boulders deposited during the 2010–2011 Canterbury earthquake sequence (CES) (n = 185) with those deposited prior to the CES (n = 1093). Population ratios of pre-CES to CES boulders at two study sites vary spatially from 5:1 to 8.5:1. This is interpreted to reflect (i) variations in CES rockfall flux due to intra- and inter-event spatial differences in ground motions (e.g. directionality) and associated variations in source cliff responses, (ii) possible variations in the triggering mechanism(s), frequency, flux, record duration, boulder size distributions, and post-depositional mobilization of pre-CES rockfalls relative to CES rockfalls, and (iii) geological variations in the source cliffs of CES and pre-CES rockfalls. On interfluves, CES boulders traveled approximately 100 to 250 m further downslope than prehistoric (pre-CES) boulders, interpreted to reflect reduced resistance to CES rockfall transport due to preceding anthropogenic hillslope de-vegetation. Volcanic breccia boulders are more dimensionally equant, rounded, larger, and traveled further downslope than coherent lava boulders, illustrating clear geological control on rockfall hazard. In valley bottoms, the furthest-traveled pre-CES boulders are situated further downslope than CES boulders due to (i) remobilization of pre-CES boulders by post-depositional processes such as debris flows, and (ii) reduction of CES boulder velocities and travel distances by collisional impacts with pre-CES boulders. A considered earth-systems approach is required when using preserved distributions of rockfall deposits to predict the severity and extents of future rockfall events.

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“…1) caused unexpectedly extreme levels of damage and disruption, being an unparalleled event in New Zealand in terms of the damage caused (e.g., Bradley, 2012). The sequence, with more than 8700 aftershocks of M L 2 or larger by March 2012 (Bannister and Gledhill, 2012), started with the magnitude M w 7.1 Darfield shallow (h 10:8 km; Gledhill et al, 2011) earthquake of 4 September 2010, which produced an ∼30-km-long east-west surface rupture 40 km west of Christchurch that resulted in the expression of the previously unknown Greendale fault Bannister and Gledhill, 2012;Quigley et al, 2012).…”

Section: The Canterbury Earthquake Sequencementioning

confidence: 99%

Analysis of the Severe-Damage Online Felt Reports for the Canterbury (New Zealand) 2011 Aftershocks on 22 February Mw 6.2, 13 June Mw 6.0, and 23 December Mw 6.0

Goded

Cousins

Fenaughty

2014

Seismological Research Letters

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Ground motions observed in the Darfield and Christchurch earthquakes and the importance of local site response effects

Cited by 31 publications

References 7 publications

Geologic and geomorphic controls on rockfall hazard: how well do past rockfalls predict future distributions?

Geologic and geomorphic controls on rockfall hazard: how well do past rockfalls predict future distributions?

Geologic and geomorphic controls on rockfall hazard: how well do past rockfalls predict future distributions?

Analysis of the Severe-Damage Online Felt Reports for the Canterbury (New Zealand) 2011 Aftershocks on 22 February Mw 6.2, 13 June Mw 6.0, and 23 December Mw 6.0

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