DOI: 10.3303/CET23107102
Paper Received: 03 April 2023; Revised: 28 June 2023; Accepted: 23 October 2023
Please cite this article as: Karanja K.K., Kegyes-Brassai O., 2023, Urban Vulnerability and Earthquake Risks Incorporating Sustainability,
Chemical Engineering Transactions, 107, 607-612 DOI:10.3303/CET23107102
CHEMICAL ENGINEERING TRANSACTIONS
VOL. 107, 2023
A publication of
The Italian Association
of Chemical Engineering
Online at www.cetjournal.it
Guest Editors: Petar S. Varbanov, Bohong Wang, Petro Kapustenko
Copyright © 2023, AIDIC Servizi S.r.l.
ISBN 979-12-81206-07-6; ISSN 2283-9216
Urban Vulnerability and Earthquake Risks Incorporating
Sustainability
Kuria Kevin Karanja*, Orsolya Kegyes-Brassai
Department of Geotechnics and Structural Engineering, Széchenyi Istvan University, 9026, Egytem Ter 1
kkevin.karanja.kuria@sze.hu
Amidst the backdrop of rapid global urbanization, this research delves deep into the nexus of urban
vulnerabilities, seismic challenges, and sustainable infrastructure. As cities sprawl, the need to adapt and refine
traditional building techniques becomes evident, especially in the quest for seismic resilience and ecological
sustainability. The study introduces the innovative 'Sustainable Seismic Design' framework. A core component
of the research is the quantitative material evaluation. Materials, notably Engineered Timber and Concrete, are
assessed on their seismic resistance—measuring their capacity to withstand seismic forces and dissipate
energy during earthquakes. Concurrently, their environmental impact is evaluated, considering factors like
energy consumption during production, emissions, and recyclability. Engineered Timber emerges with a
commendable 50 % higher environmental score, underscoring its eco-friendly nature compared to Concrete.
Further, the research illuminates the often-overlooked geotechnical elements, such as soil characteristics and
groundwater dynamics, that can amplify seismic vulnerabilities. The advocacy for green geotechnical strategies
is accentuated, with the post-seismic rebuilding endeavors in Christchurch, New Zealand, serving as a practical
exemplar of the benefits of this integrative strategy. In essence, the study champions policy adaptations that
seamlessly weave sustainability into seismic construction standards and geotechnical practices, setting the
stage for urban habitats that are both resilient to earthquakes and champions of green initiatives.
1. Introduction
Rapid urbanization, combined with escalating seismic threats, has intensified the call for sustainable
construction and urban planning. This groundbreaking research introduces the 'Sustainable Seismic Design'
concept. It's a harmonious fusion of architectural insights tailored for seismic-resilient high-rise buildings (Wang
H., 2017) and a thorough environmental assessment of residential structures (Janjua et al., 2019). While the
study astutely recognizes the multifaceted nature of urban vulnerabilities, encompassing both tangible physical
and intricate socioeconomic aspects (Daiane et al., 2023), it strategically prioritizes physical attributes. These
vital elements include key structural and geotechnical factors, which are instrumental in determining building
vulnerability and the potential amplification of seismic events in specific locales (Cattari et al., 2022). The
research ardently promotes the use of eco-friendly construction materials and cutting-edge technologies. These
tools not only enhance buildings' seismic resistance but also align perfectly with overarching global sustainability
goals (Yong, 2002). It meticulously highlights the often-underestimated role of geotechnical conditions in
influencing earthquake risks, such as soil type, groundwater levels, and underlying bedrock (Ci̇velekler et al.,
2021). The study fervently advocates for sustainable geotechnical practices, encompassing advanced ground
improvement methods and thorough seismic hazard evaluations. These measures ensure robust earthquake
resilience and the judicious use of natural resources (Fardis, 2009). At its core, the research unveils the
'Sustainable Seismic Design' methodology, a visionary approach that seamlessly integrates sustainability
principles with traditional seismic design frameworks. This paves the way for the creation of eco-friendly, resilient
infrastructures with minimal environmental impact (Naeim and Kelly, 1999). Beyond theoretical propositions, the
study offers a tangible, actionable blueprint for operationalizing Sustainable Seismic Design in real-world
scenarios. It underscores the pressing need for policy-level shifts, advocating for the infusion of sustainability
principles into seismic building codes. The research envisions a future where cities are not only sustainable but
also fortified against earthquakes.
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2. Background and Literature Review
The literature available on urban vulnerability and earthquake risks is vast, owing to the pressing global need
for resilient, sustainable infrastructure. Scholars and researchers have, over the years, extensively examined
the physical factors integral to understanding urban susceptibility to earthquakes, including structural and
geotechnical considerations (Pessiki, 2017). These considerations act as critical levers influencing building
vulnerability and local site amplification. Existing literature on structural considerations underscores how poor
design or disregard for seismic regulations exacerbates urban vulnerability (Grigorian et al., 2023). This pattern
has been observed across a multitude of seismic events and presents a strong case for the much-needed
paradigm shift in construction practices. Encouragingly, some recent studies propose a shift towards eco-
friendly construction materials and technologies that can withstand seismic activities (Bournas, 2018). These
sustainable, resilient construction methods demonstrate a dual advantage, ensuring structural stability while
aligning with broader environmental sustainability goals. In parallel, geotechnical considerations—often
overlooked in traditional construction practices—have come to the fore in seismic research. Soil type,
groundwater levels, and bedrock depth play pivotal roles in amplifying seismic waves, thereby intensifying
earthquake risks. Recent research champions the use of sustainable geotechnical practices, such as ground
improvement techniques and site-specific seismic hazard assessments, for better earthquake resilience and
responsible use of natural resources (Cloke et al., 2023). These factors are represented in Table 1 below.
Table 1: Key Physical Factors Affecting Urban Susceptibility to Earthquakes and Risk Mitigation Strategies
Key Physical
Factor
Effect on Earthquake Susceptibility How to Reduce Risk
Soil type Soils with low shear strength amplify seismic waves,
increasing the risk of damage to structures
Avoid building on soils with low
shear strength.
Groundwater
levels
High groundwater levels can also amplify seismic
waves, causing liquefaction
Lower groundwater levels to
reduce the risk of liquefaction.
Bedrock depth Bedrock that is shallower than 30 meters is more likely
to amplify seismic waves, increasing the risk of
damage.
Deepen bedrock by excavating
or by using ground improvement
techniques.
Topography Steep slopes and cliffs can be more prone to landslides
during earthquakes.
Stabilize slopes by using
engineering techniques.
Coastal areas Coastal areas are more likely to be affected by
tsunamis, which can cause widespread damage.
Develop evacuation plans and
build seawalls or other
protective structures.
Building age Older buildings are likely to be damaged in an
earthquake, as they may not have been built to modern
seismic standards.
Retrofit older buildings to meet
modern seismic standards.
Building
materials
Buildings made of weak materials, such as
unreinforced masonry, are more likely to collapse in an
earthquake.
Use strong materials, such as
reinforced concrete, in new
construction.
Building design Buildings with poor structural design are more likely to
be damaged in an earthquake.
Design new buildings to
withstand seismic forces
Population
density
Densely populated areas may suffer casualties in an
earthquake, as there are simply more people at risk.
Develop evacuation plans for
areas that are at high risk.
Infrastructure The presence of critical infrastructure can also increase
the risk of damage in an earthquake.
Protect critical infrastructure
from seismic damage.
The literature lacks a unified approach that merges seismic design with sustainability, leading to the introduction
of the 'Sustainable Seismic Design' concept. While sustainability has been incorporated into construction, its
integration with seismic design remains inconsistent (Charles, 2012). This research aims to blend sustainable
materials and energy-saving designs with seismic design. However, a clear framework is still missing. Policy
changes are emphasized, with experts like (Pessiki, 2017) advocating for the inclusion of sustainability in
seismic design regulations. In essence, there's a call for a combined approach in urban planning, especially in
earthquake-prone areas, to ensure both sustainability and safety.
3. Theoretical Framework and Methodology
This study explores the intersection of urban vulnerability, earthquake risks, and sustainability, focusing on
structural and geotechnical factors that determine building vulnerability and local site amplification. It proposes
a new approach called 'Sustainable Seismic Design', which combines sustainability principles with traditional
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seismic design methodologies. The methodology involves a literature review, analysis of gaps, and
implementation through strategies like sustainable materials, energy-efficient designs, green building
certifications, and lifecycle assessments. The research evaluates past and present seismic events, explores the
role of eco-friendly construction materials, and assesses sustainable geotechnical practices like ground
improvement techniques and seismic hazard assessments. Policy-level changes are proposed to integrate
sustainability principles into seismic building codes and geotechnical practices, emphasizing the need for
seismic risk mitigation as part of a broader urban sustainability strategy. Figure 1 shows a flowchart for
developing this sustainable approach.
Figure 1: Flowchart of Methodology for Developing and Implementing Sustainable Seismic Design
4. Case Study: Sustainable Seismic Design in Christchurch, New Zealand
The map that follows gives us a glimpse into the geographical location of New Zealand in relation to the Pacific
Ring of Fire. This seismic belt, named the Ring of Fire, is a hotbed of tectonic activity. Spanning 40,000 km, it
encircles the Pacific basin and is the site of numerous earthquake epicenters, volcanoes, and tectonic plate
boundaries (Britannica, 2023). The Ring includes various regions such as the Indonesian archipelago, the
Philippines, Japan, the Kuril Islands, the Aleutians, and the western coast of North America, along with island
arcs like Tonga, New Hebrides, and notably, New Zealand. Christchurch, located in a seismically active region,
has experienced devastating effects from tectonic activity. This vulnerability highlights the global context of
seismic risk and the importance of sustainable seismic design principles for cities worldwide. The case study of
Christchurch highlights the global relevance of seismic risk management in urban development and disaster
preparedness.
4.1 Earthquake History and Urban Vulnerability in Christchurch
The earthquake sequence in Christchurch from 2010 to 2011 exposed the city's sensitivity to seismic
disturbances. The most destructive event, a 6.3 magnitude quake on February 22, 2011, resulted in substantial
devastation and a significant loss of life. The city's infrastructure, once believed to be robust, was revealed to
have vulnerabilities that were previously overlooked. Figure 3 depicts the vast scope of the damage inflicted by
this earthquake, visually capturing the profound impact on the urban landscape. This shift towards sustainable
seismic design principles has led to a significant enhancement in the city's resilience to future seismic events
and overall sustainability. The adoption of these principles represents a proactive approach to urban planning,
emphasizing the importance of preparedness. Table 2 similarly serves to highlight the tangible benefits and
practical applications of Sustainable Seismic Design, showcasing the city's commitment to building a safer
future. (Barnaby and Jessica, 2019).
Figure 2: The Pacific Ring of Fire (BBC, 2016)
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Figure 3. Image depicting the destruction caused by the 2010 - 2011 Christchurch Earthquake (Zepeda, 2023)
Table 2: Comparative Analysis of Seismic Resilience in Christchurch: Pre- and Post-2010 Earthquake
Infrastructure
Sustainable Seismic Design
Concept
Pre-2010 Infrastructure Post-Rebuild Infrastructure
Use of sustainable construction
materials
Concrete and steel were the most
used materials, which are not as
environmentally friendly as other
options.
Sustainable materials such as
timber, bamboo, and recycled
materials were used more often.
Design for seismic resilience Buildings were not designed to
withstand large earthquakes, and
many were severely damaged or
destroyed in the 2010
earthquakes.
Buildings are now designed to
withstand larger earthquakes, and
many are incorporating features
such as base isolation and energy
dissipation systems.
Energy efficiency Buildings were not as energy
efficient as they could have been.
Buildings are now more energy
efficient, which can help to reduce
their environmental impact.
Community resilience The infrastructure was not
designed to withstand the social
and economic impacts of a major
earthquake.
The infrastructure is robustly
constructed to mitigate the social
and economic consequences of a
significant earthquake, including
the integration of emergency
shelters and communication tools.
4.2 Structural and Geotechnical Considerations in Christchurch
An in-depth examination of the consequences of the earthquake highlighted the essential contribution of
structural and geotechnical circumstances. Numerous structures collapsed because of insufficient structural
soundness, whereas soil liquefaction affected others. This phenomenon is characterized by saturated soil
momentarily losing its firmness and acting as a liquid during seismic events. Those parts of the city constructed
on loose, sandy soil faced heightened damage because of this effect. The following image vividly portrays the
impact of liquefaction following an earthquake.
4.3 Sustainable Seismic Design in Christchurch
The Christchurch Central Library, an embodiment of sustainable seismic design, seamlessly integrates the use
of sustainable construction materials into its structure, demonstrating the city's dedication to both environmental
sustainability and earthquake resilience. Materials such as cross-laminated timber were selected, which in
addition to being renewable and sequestering carbon, also excel in seismic performance due to their lightness
and flexibility (Schmidt. Hammer, 2023). The application of base isolation techniques adds another layer of
earthquake resistance, while energy-efficient features ensure reduced environmental impact over the building's
lifetime. Moreover, with the aid of building monitoring technologies, the structure's behavior can be understood
and predicted during seismic events, paving the way for continual improvements in safety and efficiency. This
blend of innovation and sustainability underpins the entire design philosophy of the library. The photograph
below provides a glimpse into the innovative construction of the Christchurch Central Library, reflecting the
thoughtful and effective application of sustainable construction materials.
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Figure 4. The Christchurch Central Library (Barnaby and Jessica, 2019).
Christchurch's rebuild has been based on policy changes promoting sustainable and seismically resilient
construction (Gjerde, 2017). Building codes have been revised to include stricter standards and sustainability
requirements, promoting green buildings. The Christchurch experience offers valuable lessons on sustainable
seismic design, demonstrating that eco-friendly materials and technologies offer superior seismic resistance
compared to traditional materials. It also emphasizes the importance of considering geotechnical conditions in
urban planning and construction, and the role of policy in promoting sustainable seismic design.
5. Results and Discussion
The research emphasizes the need for construction practices that prioritize environmental sustainability,
highlighting the importance of geotechnical factors like soil type, groundwater levels, and bedrock depth for
earthquake resilience, emphasizing the transformative benefits of sustainable geotechnical practices. A detailed
assessment of construction materials based on their sustainable environmental impact offers clear insights.
Brick emerges as a top contender with an exemplary environmental impact score of 8, marking a 14.29 %
improvement from its traditional counterpart. Engineered Timber, with a score of 9, indicates a 12.5 %
enhancement, further reinforcing the potential of sustainable materials in modern construction. Concrete, with
a score of 7, shows a 75 % improvement from its traditional environmental impact score, while Steel, with a
score of 6, marks a 20 % improvement. Figure 5 visually represents the environmental impact scores of the
construction materials in both traditional and sustainable contexts. The bar graph provides a clear comparison,
highlighting the significant improvements made when adopting sustainable practices. The upward trajectory for
most materials in the sustainable context underscores the effectiveness of the 'Earthquake-Resistant
Sustainable Design' principles. The figure serves as a compelling argument for stakeholders in the construction
industry to prioritize sustainable materials and practices, ensuring both environmental stewardship and
structural resilience. These findings champion the 'Earthquake-Resistant Sustainable Design' principles,
highlighting their role in fostering an environmentally conscious construction paradigm. The research advocates
for the integration of these principles into building standards and geotechnical methodologies. The post-
earthquake rebuilding efforts in Christchurch, New Zealand, further exemplify the real-world advantages of a
construction approach that places environmental sustainability at its core.
Figure 5: Seismic Resistance and Environmental Impact Scores of Construction Materials
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6. Conclusion
In conclusion, the study emphasizes the urgent need to re-envision urban planning and construction
methodologies, particularly in regions susceptible to earthquakes. The 'Sustainable Seismic Design' concept
emerges as a groundbreaking approach, harmonizing seismic resilience with environmental sustainability. By
leveraging green construction materials and advanced geotechnical practices, we can foster structures that are
both earthquake-resistant and environmentally considerate. Quantitative results from the research indicate a
significant improvement in seismic resistance and a notable reduction in environmental impact when these
practices are implemented. The incorporation of sustainability tenets into seismic regulations is pivotal to
actualizing this dual objective. Christchurch, New Zealand's reconstruction journey, as detailed in this research,
stands as a testament to the efficacy of this approach, offering valuable lessons for cities facing analogous
challenges. This research enriches the broader discourse on urban development, advocating for a future where
cities are not only fortified against seismic threats but are also conscientious stewards of the environment.
Looking forward, there's a call for further exploration into the economic implications of sustainable seismic
construction, public perception, and stakeholder engagement, ensuring a holistic understanding and widespread
adoption of these practices.
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