Land use planning for earthquake risk reduction Md Yousuf Reja

Global Seismic Hazard map this map shows different level earthquake ground motion across the World. Where green shows the lowest level and red highest. According to the U.S. Geological Survey (USGS), Seismic Hazard Maps display earthquake ground motions for various probability levels and are applied in seismic provisions of building codes, insurance rate structures, risk assessments, and other public policy. http://news.bbc.co.uk/2/hi/science/nature/572529.stm

High seismic hazard does not necessarily mean high earthquake risk, and vice versa. Earthquake risk depends on combination of both seismic hazard and exposure (people or buildings) However, high seismic hazard does not necessarily mean high earthquake risk, and vice versa. Rather, risk depends on combination of both seismic hazard and exposure. For example, there are high seismic hazards in the California deserts, but low seismic risk because of few exposures (people or buildings). On the other hand, the seismic risk could be high in some areas, such as Iran because of high exposures, even though the hazards may be moderate

Problems: “Communities will always face natural hazards, but today’s disasters are often generated by, or at least exacerbated by, human activities…… At no time in human history have so many people lived in cities clustered around seismically active areas. Destitution and demographic pressure have led more people than ever before to live in flood plains or in areas prone to seismic hazards. Poor land-use planning; environmental management; and a lack of regulatory mechanisms both increase the risk and exacerbate the effects of disasters.” ----Kofi Annan(Secretary General, 1997-2006, United Nations) When I was conducting this research, my main inspiration came from a quote, Where it highlights that Poor land-use planning; environmental management; and a lack of regulatory mechanisms both increase the risk and exacerbate the effects of disasters.” Annan, Kofi, 2002: Foreword to Living with Risk: A Global Review of Disaster Reduction Initiatives, (UN/ISDR). Quoted in UN/ISDR, 2003: Disaster Reduction and Sustainable Development. A background paper for the World Summit on Sustainable Development; http://www.unisdr.org (2006):1.

Highlights of this presentation: Enhancing the safety of built environments and reducing the earthquake risk by land use planning with integration of seismic-hazard map “Land use planning is one of the measures that contribute to resilience.” Paton et al (2013) It is widely recognize that the damage caused by an earthquake is a result of an interaction between the physical event and the built environment. Thus, to estimate potential losses, one must both understand an area’s seismic risk and have information on the area’s population, land use, and structures. D. Paton, L.Mamula-Seadon, K.Selway, Community Resilience in Christchurch: Adaptive Responses and Capacities During Earthquake Recovery, GNS Science, LowerHutt,2013,GNSScienceReport2013/37.

Benefit of Land Use Planning in earthquake risk reduction : “Land use planning techniques are useful and potentially less costly than some other mitigation measures, particularly structural ones, that decrease earthquake loss potential” ---Bolton, 1986 (Land use planning for earthquake hazard mitigation: A handbook for planners) one of the important benefits of Land use planning in earthquake risk reduction is Land use planning methods are less costly than structural mitigation measures Bolton, P. A. (1986). Land use planning for earthquake hazard mitigation: A handbook for planners..

Steps for considering land use planning in earthquake risk reduction (A case study example of Chittagong City, Bangladesh): Preparation of seismic-microzonation map Preparation of map including existing land use distribution and essential features of the built environment (also known as land use inventory) Risk assessment by overlaying maps and future consideration In this study, three important steps were used. Firstly, Preparation of seismic-microzonation map then Preparation of map including existing land use distribution and essential features of the built environment (also known as land use inventory) Finally, Risk assessment by overlaying two maps for future consideration

Location of case study area: Before going to further details of the process, it is important to know the location of the study area. Chittagong is the second largest city of Bangladesh with a population of 1.59 million and is the commercial capital of the country.  Located in the southeast of Bangladesh. Based on historic earthquakes and time period, Chittagong is now considered as a serious earthquake prone zone where a major earthquake may occur at any time. Moreover, its rapid urban growth is causing further deterioration and increasing the vulnerability of human lives, economy and infrastructures.  http://news.bbc.co.uk/2/hi/science/nature/572529.stm https://www.onestopmap.com/product/printable-vector-map-bangladesh-political-25/ http://en.banglapedia.org/index.php?title=Chittagong_City_Corporation

Seismic-microzonation map: Various methods can be used to map the seismic hazard Chittagong city seismic-microzonation map was prepared form measuring soil amplification, liquefaction, and landslide hazard Firstly, a seismic-microzonation map was prepared by measuring soil amplification, liquefaction, and landslide hazard. In this map, black color shows the high intensity, dark gray medium intensity and light gray represents low intensity earthquake ground motion. Map showing regional distribution of combined seismic Hazard (MMI) in Chittagong City (Administrative Boundary) (Source: Aniussazaman M. 2002)

Seismic-microzonation map: Map of active faults in Chittagong City A map showing existing fault lines was prepared and data collected from CDA (Chittagong Development Authority) geographic division (2007). It identifies the probable hazardous areas In this research, I also considered a map of active fault lines along with the seismic microzonation map. This map was prepared using GIS and data collected from CDA geographic Division. It basically identifies the probable hazardous areas for future consideration. Some literature suggest that such microzonation mapping can provide the informational basis for applying land use planning techniques to earthquake loss reduction· through zoning, subdivision ordinances, special use and critical facility permits, lifeline (roads and utilities) planning, property acquisition programs, and other measures Map showing existing fault lines in Chittagong City. Source: Mominullah (CMMP (2007) (Reja, 2008)

Existing Land Use map (proposed by CMMP 2007): This map shows the location patterns and type of land uses Major transportation network The next map highlights the spatial distribution of different land use types proposed by the Chittagong Metropolitan Master plan (2007) for the period of 2009-2029. it also shows the proposed major transportation network Proposed land use map of Chittagong city for the period of 2009-2029 (Source: Chittagong Metropolitan Master Plan 2007)

Existing Land Use distribution (CMMP 2007):

Seimic microzonation map Risk Assessment by overlaying maps: Land use map Seimic microzonation map Finally, Using GIS, these three maps overlaid each other to identify the areas and particularly the residential types that are vulnerable to high earthquake risk. It also analyzed the expected intensity at different sites of the Chittagong city. Map of fault lines

Results: More than 39.40% of residential (both planned and unplanned) zones were considered to have high risk, where 21.67% were proposed for future expansion Approximately 17% of new business districts proposed in CMMP 2007 land use have greater earthquake risk Results from these analyses show that more than 39.40% of residential zones are considered to have high risk, where 21.67% were proposed for future residential development. Results also show that 17% of proposed business ditricts have high earthquake vulnerability.

Results: Bayezid Bostami, Halishahar, part of Phartoli, Potenga (port area), and Double Mooring area have high intensity earthquake risk Two of the new proposed highway fall above the fault lines It also show that Bayezid Bostami, Halishahar, part of Phartoli, Potenga (port area), and Double Mooring area have high intensity earthquake risk. Where Bayezid Bostami and Halishahar are the area for new developments in CMMP 2007 proposed land use map. Finally, it found that two proposed highway were laid above the fault lines.

Discussions: Several future land use scenario can be generated and then evaluated for comparative risk Avoiding buildings from potentially high hazard areas Further research on structural measures and retrofitting consideration for buildings those already built in high hazard areas By comparing the earthquake risk---- we can generate several land use scenario. We can avoid physical developments from high hazard areas And, further research can be done for retrofitting the buildings that are already existed in vulnerable areas

Discussions: A zone of high hazard area might be designed as city park Based on the potential severity of hazards and active fault lines, city’s lifelines can be designed Urban planner should consider seismic microzonation in reducing earthquake vulnerability by developing appropriate land use plan to guide the urban development Moreover, A zone of high hazard area might be designed as city park City’s lifelines can be designed based on active faultlines and severity of vulnerability Finally, seismic microzonation should be a priority for planners development will take place in an earthquake prone area

Examples: Christchurch provides examples of resilient (i.e. TC area zoning), and sustainable (i.e. red zoning), land use planning for earthquake risk reduction. Where red areas marked for structural mitigation. And, other colors identified as technical category zones. Where 1 shows low damage and 3 indicates high damage. Map of greater Christchurch area showing red and TC zones developed for residential properties Saunders, W. S. A., & Becker, J. S. (2015). A discussion of resilience and sustainability: Land use planning recovery from the Canterbury earthquake sequence, New Zealand. International Journal of Disaster Risk Reduction,14, 73-81.

“If we cannot control the volatile tides of change, we can learn to build better boats.” —Andrew Zolli and Ann Marie Healy, Resilience: Why Things Bounce Back (2012) Lastly, I want to finish my presentation with one of my favorite quote “If we cannot control the volatile tides of change, we can learn to build better boats.” Thus, this presentation shows how seismic-hazard zoning map integrated with land use planning can help to make a resilient city or help to build a better boats. Because, the big one can come anytime. http://www.geekwire.com/2015/how-can-you-prepare-for-the-really-big-one-7-tips-from-pnw-earthquake-experts/

Thank You