The Avon-Heathcote Estuary, located in Christchurch, New Zealand, experienced coseismic deformation as a result of the February 22nd 2011 Christchurch Earthquake. The deformation is reflected as subsidence in the northern area and uplift in the southern area of the Estuary, in addition to sand volcanoes which forced up sediment throughout the floor of the Estuary altering estuary bed height and tidal flow. The first part of the research involved quantifying the change in the modern benthic foraminifera distribution as a result of the coseismic deformation caused by the February 22nd 2011 earthquake. By analysing the taxa present immediately post deformation and then the taxa present 2 years post deformation a comparison of the benthic foraminifera distribution can be made of the pre and post deformation. Both the northern and the southern areas of the Estuary were sampled to establish whether foraminifera faunas migrated landward or seaward as a result of subsidence and uplift experienced in different areas. There was no statistical change in overall species distribution in the two year time period since the coseismic deformation occurred, however, there were some noticeable changes in foraminifera distribution at BSNS-Z3 showing a landward migration of taxa. The changes that were predicted to occur as a result of the deformation of the Estuary are taking longer than expected to show up in the foraminiferal record and a longer time period is needed to establish these changes. The second stage involved establishing the modern distribution of foraminifera at Settlers Reserve in the southern area of the Avon-Heathcote Estuary by detailed sampling along a 160 m transect. Foraminifera are sensitive to environmental parameters, tidal height, grainsize, pH and salinity were recorded to evaluate the effect these parameters have on distribution. Bray-Curtis two-way cluster analysis was primarily used to assess the distribution pattern of foraminifera. The modern foraminifera distribution is comparable to that of the modern day New Zealand brackish-water benthic foraminifera distribution and includes species not yet found in other studies of the Avon-Heathcote Estuary. Differences in sampling techniques and the restricted intertidal marshland area where the transect samples were collected account for some of the differences seen between this model and past foraminifera studies. xiii The final stage involved sampling a 2.20 m core collected from Settlers Reserve and using the modern foraminiferal distribution to establish a foraminiferal history of Settlers Reserve. As foraminifera are sensitive to tidal height they may record past coseismic deformation events and the core was used to ascertain whether record of past coseismic deformation is preserved in Settlers Reserve sediments. Sampling the core for foraminifera, grainsize, trace metals and carbon material helped to build a story of estuary development. Using the modern foraminiferal distribution and the tidal height information collected, a down core model of past tidal heights was established to determine past rates of change. Foraminifera are not well preserved throughout the core, however, a sudden relative rise in sea level is recorded between 0.25 m and 0.85 m. Using trace metal and isotope analysis to develop an age profile, this sea level rise is interpreted to record coseismic subsidence associated with a palaeoseismic event in the early 1900’s. Overall, although the Avon-Heathcote Estuary experienced clear coseismic deformation as a result of the 22nd of February 2011 earthquake, modern changes in foraminiferal distribution cannot yet be tracked, however, past seismic deformation is identified in a core. The modern transect describes the foraminifera distribution which identifies species that have not been identified in the Avon-Heathcote Estuary before. This thesis enhances the current knowledge of the Avon-Heathcote Estuary and is a baseline for future studies.

Reaches dominated by debris flow scour and incision tend to greatly influence landscape form in steepland basins. Debris flow networks, despite their ubiquity, have not been exploited to develop erosion rate proxies. To bridge this gap, I applied a proposed empirical function that describes the variation of valley slope with drainage area in fluvial and debris flow reaches of steepland channel networks in the Oregon Coast Range. I calibrated a relationship between profile concavity and erosion rate to map spatial patterns of long-term uplift rates assuming steady state. I also estimated the magnitude and inland extent of coseismic subsidence in my study area. My estimates agree with field measurements in the same area along the Cascadia margin, indicating that debris flow valley profiles can be used to make interpretations from spatial patterns of rock uplift that may better constrain physical models of crustal deformation. This thesis includes unpublished co-authored material.

Disasters can occur without warning and severely test society’s capacity to cope, significantly altering the relationship between society and the built and natural environments. The scale of a disaster is a direct function of the pre-event actions and decisions taken by society. Poor pre-event planning is a major contributor to disaster, while effective pre-event planning can substantially reduce, and perhaps even avoid, the disaster. Developing and undertaking effective planning is therefore a vital component of disaster risk management in order to achieve meaningful societal resilience. Disaster scenarios present arguably the best and most effective basis to plan an effective emergency response to future disasters. For effective emergency response planning, disaster scenarios must be as realistic as possible. Yet for disasters resulting from natural hazards, intricately linked secondary hazards and effects make development of realistic scenarios difficult. This is specially true for large earthquakes in mountainous terrain. The primary aim of this thesis is therefore to establish a detailed and realistic disaster scenario for a Mw8.0 earthquake on the plate boundary Alpine fault in the South Island of New Zealand with specific emphasis on secondary effects. Geologic evidence of re-historic earthquakes on this fault suggest widespread and large-scale landsliding has resulted throughout the Southern Alps, yet, currently, no attempts to quantitatively model this landsliding have been undertaken. This thesis therefore provides a first attempt at quantitative assessments of the likely scale and impacts of landsliding from a future Mw8.0 Alpine fault earthquake. Modelling coseismic landsliding in regions lacking historic inventories and geotechnical data (e.g. New Zealand) is challenging. The regional factors that control the spatial distribution of landsliding however, are shown herein to be similar across different environments. Observations from the 1994 Northridge, 1999 Chi-Chi, and 2008 Wenchuan earthquakes identified MM intensity, slope angle and position, and distance from active faults and streams as factors controlling the spatial distribution of landsliding. Using fuzzy logic in GIS, these factors are able to successfully model the spatial distribution of coseismic landsliding from both the 2003 and 2009 Fiordland earthquakes in New Zealand. This method can therefore be applied to estimate the scale of landsliding from scenario earthquakes such as an Alpine fault event. Applied to an Mw8.0 Alpine fault earthquake, this suggests that coseismic landsliding could affect an area >50,000 km2 with likely between 40,000 and 110,000 landslides occurring. Between 1,400 and 4,000 of these are expected to present a major hazard. The environmental impacts from this landsliding would be severe, particularly in west-draining river catchments, and sediment supply to rivers in some catchments may exceed 50 years of background rates. Up to 2 km3 of total landslide debris is expected, and this will have serious and long-term consequences. Fluvial remobilisation of this material could result in average aggradation depths on active alluvial fans and floodplains of 1 m, with maximum depths substantially larger. This is of particular concern to the agriculture industry, which relies on the fertile soils on many of the active alluvial fans affected. This thesis also investigated the potential impacts from such landsliding on critical infrastructure. The State Highway and electrical transmission networks are shown to be particularly exposed. Up to 2,000 wooden pole and 30 steel pylon supports for the transmission network are highly exposed, resulting in >23,000 people in the West Coast region being exposed to power loss. At least 240 km of road also has high exposure, primarily on SH6 between Hokitika and Haast, and on Arthur’s and Lewis Passes. More than 2,750 local residents in Westland District are exposed to isolation by road as a result. The Grey River valley region is identified as the most critical section of the State Highway network and pre-event mitigation is strongly recommended to ensure the road and bridges here can withstand strong shaking and liquefaction hazards. If this section of the network can remain functional post-earthquake, the emergency response could be based out of Wellington using Nelson as a forward operating base with direct road access to some of the worst-affected locations. However, loss of functionality of this section of road will result in >24,000 people becoming isolated across almost the entire West Coast region. This thesis demonstrates the importance and potential value of pre-event emergency response planning, both for the South Island community for an Alpine fault earthquake, and globally for all such hazards. The case study presented demonstrates that realistic estimates of potential coseismic landsliding and its impacts are possible, and the methods developed herein can be applied to other large mountainous earthquakes. A model for developing disaster scenarios in collaboration with a wide range of societal groups is presented and shown to be an effective method for emergency response planning, and is applicable to any hazard and location globally. This thesis is therefore a significant contribution towards understanding mountainous earthquake hazards and emergency response planning.

Case study analysis of the 2010-2011 Canterbury Earthquake Sequence (CES), which particularly impacted Christchurch City, New Zealand, has highlighted the value of practical, standardised and coordinated post-earthquake geotechnical response guidelines for earthquake-induced landslides in urban areas. The 22nd February 2011 earthquake, the second largest magnitude event in the CES, initiated a series of rockfall, cliff collapse and loess failures around the Port Hills which severely impacted the south-eastern part of Christchurch. The extensive slope failure induced by the 22nd February 200 earthquake was unprecedented; and ground motions experienced significantly exceeded the probabilistic seismic hazard model for Canterbury. Earthquake-induced landslides initiated by the 22nd February 2011 earthquake posed risk to life safety, and caused widespread damage to dwellings and critical infrastructure. In the immediate aftermath of the 22nd February 2011 earthquake, the geotechnical community responded by deploying into the Port Hills to conduct assessment of slope failure hazards and life safety risk. Coordination within the voluntary geotechnical response group evolved rapidly within the first week post-earthquake. The lack of pre-event planning to guide coordinated geotechnical response hindered the execution of timely and transparent management of life safety risk from coseismic landslides in the initial week after the earthquake. Semi-structured interviews were conducted with municipal, management and operational organisations involved in the geotechnical response during the CES. Analysis of interview dialogue highlighted the temporal evolution of priorities and tasks during emergency response to coseismic slope failure, which was further developed into a phased conceptual model to inform future geotechnical response. Review of geotechnical responses to selected historical earthquakes (Northridge, 1994; Chi-Chi, 1999; Wenchuan, 2008) has enabled comparison between international practice and local response strategies, and has emphasised the value of pre-earthquake preparation, indicating the importance of integration of geotechnical response within national emergency management plans. Furthermore, analysis of the CES and international earthquakes has informed pragmatic recommendations for future response to coseismic slope failure. Recommendations for future response to earthquake-induced landslides presented in this thesis include: the integration of post-earthquake geotechnical response with national Civil Defence and Emergency Management; pre-earthquake development of an adaptive management structure and standard slope assessment format for geotechnical response; and emergency management training for geotechnical professionals. Post-earthquake response recommendations include the development of geographic sectors within the area impacted by coseismic slope failure, and the development of a GIS database for analysis and management of data collected during ground reconnaissance. Recommendations provided in this thesis aim to inform development of national guidelines for geotechnical response to earthquake-induced landslides in New Zealand, and prompt debate concerning international best practice.

Past earthquake rupture models used to explain paleoseismic estimates of coastal subsidence during the great AD 1700 Cascadia earthquake have assumed a uniform slip distribution along the megathrust. Here, we infer heterogeneous slip for the Cascadia margin in AD 1700 that is analogous to slip distributions during instrumentally recorded great subduction earthquakes worldwide. The assumption of uniform distribution in previous rupture models was due partly to the large uncertainties of available paleoseismic data used to constrain the models. In this work, we use more precise estimates of subsidence in 1700 from detailed tidal microfossil studies. We develop a 3-D elastic dislocation model that allows the slip to vary both along strike and in the dip direction. Despite uncertainties in the updip and downdip slip extents, the more precise subsidence estimates are best explained by a model with along-strike slip heterogeneity, with multiple patches of high moment release separated by areas of low moment release. For example, in AD 1700 there was very little slip near Alsea Bay, Oregon (~ 44.5°N), an area that coincides with a segment boundary previously suggested on the basis of gravity anomalies. A probable subducting seamount in this area may be responsible for impeding rupture during great earthquakes. Our results highlight the need for precise, high-quality estimates of subsidence or uplift during prehistoric earthquakes from the coasts of southern British Columbia, northern Washington (north of 47°N), southernmost Oregon, and northern California (south of 43°N), where slip distributions of prehistoric earthquakes are poorly constrained. / Graduate

The Hines Creek fault (HCF) is a Holocene-active fault in central Alaska. Its trace has been mapped several times, but data on the history of fault displacement is scarce. As a major crustal-scale geologic boundary with uncertain Quaternary tectonic activity, it is a priority for more to be known about the activity of this fault to better understand the hazards it presents to the Denali National Park and Preserve and Alaskan infrastructure. This study characterizes the late Quaternary activity of the HCF through surficial geologic mapping and paleoseismic investigations. Mapping revealed a very steep (~84°-88° apparent dip), north dipping fault plane and measurements from offset Pleistocene outwash terraces revealed south side-down vertical offsets of up to 12 m, indicating a steeply dipping reverse fault. Three paleoseismic trenches excavated across the fault trace provided a record of seismic activity and hold evidence for at least four prehistoric earthquakes in the last 2 ka. Slip rate calculations estimate movement on the HCF to be between 0.6mm yr-1 and1.2 mm yr-1. The active trace of the HCF follows the southern margin of the tectonically active Mount Healy anticline, suggesting a kinematic linkage between the fault that underlies this anticline and the HCF.

京都大学 / 0048 / 新制・論文博士 / 博士(理学) / 乙第13300号 / 論理博第1563号 / 新制||理||1653(附属図書館) / (主査)准教授 王 功輝, 教授 釜井 俊孝, 教授 福田 洋一 / 学位規則第4条第2項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19283号 / 工博第4080号 / 新制||工||1629(附属図書館) / 32285 / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 田村 正行, 教授 小池 克明, 准教授 須﨑 純一 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

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京都大学 / 新制・課程博士 / 博士(理学) / 甲第24171号 / 理博第4862号 / 新制||理||1695(附属図書館) / 京都大学大学院理学研究科地球惑星科学専攻 / (主査)准教授 西村 卓也, 教授 宮﨑 真一, 准教授 深畑 幸俊 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM