A search for teleseismicPresidual changes before large earthquakes in New Zealand

1974 ◽  
Vol 79 (23) ◽  
pp. 3283-3290 ◽  
Author(s):  
M. Wyss ◽  
A. C. Johnston
Keyword(s):  
New Zealand ◽  
Large Earthquakes

scholarly journals Detection of Large Holocene Earthquakes in the Sedimentary Record of Wellington, New Zealand, Using Diatom Analysis

2021 ◽  
Author(s):  
◽  
Ursula Alyson Cochran
Keyword(s):  
New Zealand ◽  
Late Holocene ◽  
Weighted Averaging ◽  
Diatom Analysis ◽  
Sedimentary Record ◽  
Sedimentary Sequences ◽  
Quantitative Estimates ◽  
Modern Analogue ◽  
Environmental Transitions ◽  
Large Earthquakes

<p>New Zealand is situated on the boundary between the Pacific and Australian tectonic plates. The Wellington region lies near the southern end of the Hikurangi subduction zone and within a zone of major, active strike-slip faults. Wellington's paleoseismic and historic records indicate that large surface rupture earthquakes have occurred on these faults in the past. Development of a complete record of past large earthquakes is a high priority for the region because of the risk posed by occurrence of large earthquakes in the future. The existing paleoseismic record has been derived predominantly from studies of fault trench stratigraphy, raised beach ridges and offset river terraces. The sedimentary record of lakes and coastal waterbodies is a source of information that has not been used specifically for paleoseismic purposes in the region. Therefore investigation of Wellington's sedimentary record is used in this thesis to make a contribution to the paleoseismic record. Holocene sedimentary sequences are studied from three small, low elevation, coastal waterbodies: Taupo Swamp, Okupe Lagoon and Lake Kohangapiripiri. Sequences of between 200 and 650 cm depth were collected using a hand-operated coring device. Sedimentology and diatom microfossil content were analysed and interpreted to enable reconstruction of paleoenvironment at each site. Radiocarbon dating was used to provide chronologies for the sequences that are aged between 5000 and 7500 calibrated years before present (cal. years BP). Diatom analysis is the main tool used to reconstruct paleoenvironment and detect evidence for occurrence of past large earthquakes. To aid reconstruction of sedimentary sequences used in this project, as well as coastal sequences in New Zealand in general, a coastal diatom calibration set was constructed using 50 sites around New Zealand. Modern diatom distribution and abundance, and associated environmental variables are analysed using ordination and weighted averaging techniques. Detrended correspondence analysis arranges species according to salinity preferences and divides sites clearly into waterbody types along a coastal gradient. This analysis enables reconstruction of waterbody type from fossil samples by passive placement onto ordination diagrams. Weighted averaging regression of calibration set samples results in a high correlation (r2jack=0.84) between observed and diatom inferred salinity, and enables salinity preferences and tolerances to be derived for 100 species. This confirms for the first time that species' preferences derived in the Northern Hemisphere are generally applicable to diatoms living in the coastal zone of New Zealand. Weighted averaging calibration and the modern analogue technique are used to generate quantitative estimates of paleosalinity for fossil samples. Paleoenvironmental reconstructions of Taupo Swamp, Okupe Lagoon and Lake Kohangapiripiri indicate that each waterbody has been isolated from the sea during the late Holocene. Isolation has been achieved through interplay of sediment accumulation causing growth of barrier beaches, and coseismic uplift. Ten distinct transitions between different paleoenvironments are recognised from the three sequences. These transitions involve changes in relative sea level or water table level often in association with catchment disturbance or marine influx events. All transitions occur suddenly and are laterally extensive and synchronous within each waterbody. Quantitative estimates of paleosalinity and waterbody type are used to differentiate between large and small magnitude changes in paleoenvironment. Five transitions involve large amounts of paleoenvironmental change and provide evidence for earthquakes occurring at approximately 5200, approximately 3200, and approximately 2300 cal. years BP. Five other transitions are consistent with the effects of large earthquakes occurring at approximately 6800, 2200, approximately 1000, approximately 500 cal. years BP and 1855 AD but do not provide independent evidence of the events. Environmental transitions at Lake Kohangapiripiri clarify the timing of rupture of the Wairarapa Fault by bracketing incompatible age estimates derived from two different sites on the fault. The oldest environmental transitions recognised at Taupo Swamp and Okupe Lagoon both occur at approximately 3200 cal. years BP indicating that western Wellington was uplifted at this time. Environmental transitions are recorded at all three study sites at approximately 2300 cal. years BP indicating that the entire western and central Wellington region experienced coseismic uplift at this time. Because of the distance between sites this apparent synchroneity implies that several faults in the region ruptured at a similar time. Investigation of sedimentary sequences contributes to the existing paleoseismic record by providing additional estimates of timing for past large earthquakes, enabling estimation of the areal extent of the effects of past earthquakes, and by highlighting periods of fault rupture activity in the late Holocene.</p>

scholarly journals Spatial distributions of earthquake-induced landslides and hillslope preconditioning in the northwest South Island, New Zealand

2015 ◽  
Vol 3 (4) ◽  
pp. 501-525 ◽  
Author(s):  
R. N. Parker ◽  
G. T. Hancox ◽  
D. N. Petley ◽  
C. I. Massey ◽  
A. L. Densmore ◽  
...  
Keyword(s):  
New Zealand ◽  
Regional Scale ◽  
Aftershock Sequence ◽  
Spatial Distributions ◽  
Damage State ◽  
History Of ◽  
Analysis Of Failures ◽  
Seismic Landslide ◽  
Large Earthquakes ◽  
Strong Ground

Abstract. Current models to explain regional-scale landslide events are not able to account for the possible effects of the legacy of previous earthquakes, which have triggered landslides in the past and are known to drive damage accumulation in brittle hillslope materials. This paper tests the hypothesis that spatial distributions of earthquake-induced landslides are determined by both the conditions at the time of the triggering earthquake (time-independent factors) and the legacy of past events (time-dependent factors). To explore this, we under\\-take an analysis of failures triggered by the 1929 Buller and 1968 Inangahua earthquakes, in the northwest South Island of New Zealand. The spatial extents of landslides triggered by these events were in part coincident. Spatial distributions of earthquake-triggered landslides are determined by a combination of earthquake and local characteristics, which influence the dynamic response of hillslopes. To identify the influence of a legacy from past events, we first use logistic regression to control for the effects of time-independent variables. Through this analysis we find that seismic ground motion, hillslope gradient, lithology, and the effects of topographic amplification caused by ridge- and slope-scale topography exhibit a consistent influence on the spatial distribution of landslides in both earthquakes. We then assess whether variability unexplained by these variables may be attributed to the legacy of past events. Our results suggest that hillslopes in regions that experienced strong ground motions in 1929 were more likely to fail in 1968 than would be expected on the basis of time-independent factors alone. This effect is consistent with our hypothesis that unfailed hillslopes in the 1929 earthquake were weakened by damage accumulated during this earthquake and its associated aftershock sequence, which influenced the behaviour of the landscape in the 1968 earthquake. While our results are tentative, they suggest that the damage legacy of large earthquakes may persist in parts of the landscape for much longer than observed sub-decadal periods of post-seismic landslide activity and sediment evacuation. Consequently, a lack of knowledge of the damage state of hillslopes in a landscape potentially represents an important source of uncertainty when assessing landslide susceptibility. Constraining the damage history of hillslopes, through analysis of historical events, therefore provides a potential means of reducing this uncertainty.

scholarly journals Geological evidence for past large earthquakes and tsunamis along the Hikurangi subduction margin, New Zealand

2019 ◽  
Vol 412 ◽  
pp. 139-172 ◽  
Author(s):  
Kate Clark ◽  
Jamie Howarth ◽  
Nicola Litchfield ◽  
Ursula Cochran ◽  
Jocelyn Turnbull ◽  
...  
Keyword(s):  
New Zealand ◽  
Geological Evidence ◽  
Large Earthquakes

Lake sediments record cycles of sediment flux driven by large earthquakes on the Alpine fault, New Zealand

Geology ◽  
2012 ◽  
Vol 40 (12) ◽  
pp. 1091-1094 ◽  
Author(s):  
J. D. Howarth ◽  
S. J. Fitzsimons ◽  
R. J. Norris ◽  
G. E. Jacobsen
Keyword(s):  
New Zealand ◽  
Lake Sediments ◽  
Sediment Flux ◽  
Alpine Fault ◽  
Large Earthquakes

scholarly journals Revised estimates of earthquake hazard in New Zealand

1983 ◽  
Vol 16 (4) ◽  
pp. 259-272
Author(s):  
W. D. Smith ◽  
K. R. Berryman
Keyword(s):  
New Zealand ◽  
Ground Deformation ◽  
Earthquake Hazard ◽  
Earthquake Occurrence ◽  
Seismological Data ◽  
Large Earthquakes

Earlier estimates of earthquake hazard in New Zealand have been revised by incorporating not only seismological data on known large earthquakes and recent instrumental coverage of small earthquakes but also geological inference from observed ground deformation. The country has been divided into a number of regions, within each of
which the density of earthquake occurrence is assumed to be uniform, while rate parameters very from region to region. The effects of earthquakes occurring throughout each region are then obtained by integration. The results are presented in a similar way as in the earlier study. The estimated hazard is slightly reduced for Auckland, Wellington and Christchurch, and significantly increased for Dunedin.

scholarly journals Liquefaction during historic earthquakes in New Zealand

1984 ◽  
Vol 17 (4) ◽  
pp. 280-291
Author(s):  
G. J. Fairless ◽  
J . B. Berrill
Keyword(s):  
New Zealand ◽  
Alluvial Deposits ◽  
Fine Grained ◽  
Clear Cases ◽  
The Relationship ◽  
Historic Earthquakes ◽  
Large Earthquakes

The literature has been searched for accounts of liquefaction during historic earthquakes in New Zealand. About 30 fairly clear cases of liquefaction were found in 10 earthquakes since 1843. The 1848 Marlborough and the 1931 Napier earthquakes appear to have caused the most widespread occurrences. Both were large earthquakes in regions with extensive saturated fine-grained alluvial deposits. Since liquefaction has only recently been recognised as a distinct phenomenon, evidence of its occurrence was not expressly searched for in early investigations, and it is possible that many instances have gone unrecorded. Therefore it is likely that liquefaction has been more pervasive than the 30 clear cases suggest. With the exception of the M ≥ 6, 1895 Taupo earthquake which liquefied a pumice soil, all have occurred in earthquakes with magnitudes of at least 6.9. However, some larger earthquakes, most notably the 1929, M = 7.8 Murchison earthquake, have produced no records of liquefaction that we could find. Given the uncertainties of early epicentral locations, the New Zealand cases are consistent with the expression of Kuribayashi and Tatsuoka (1975) for distance to the farthest site of liquefaction, although the number of cases is too small to establish the correctness of the relationship under New Zealand conditions.

Large earthquakes and the abandonment of prehistoric coastal settlements in 15th century New Zealand

2003 ◽  
Vol 18 (6) ◽  
pp. 609-623 ◽  
Author(s):  
James R. Goff ◽  
Bruce G. McFadgen
Keyword(s):  
New Zealand ◽  
15Th Century ◽  
Large Earthquakes

Micropaleontological evidence of large earthquakes in the past 7200 years in southern Hawke's Bay, New Zealand

2006 ◽  
Vol 25 (11-12) ◽  
pp. 1186-1207 ◽  
Author(s):  
Bruce W. Hayward ◽  
Hugh R. Grenfell ◽  
Ashwaq T. Sabaa ◽  
Rowan Carter ◽  
Ursula Cochran ◽  
...  
Keyword(s):  
New Zealand ◽  
The Past ◽  
Large Earthquakes
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