Tsunami risk for the Western Indian Ocean: steps toward the integration of science into policy and practice

The 2004 Sumatra-Andaman tsunami killed around 15,000 people on the Eastern coast of India, especially from vulnerable communities who were also deeply affected economically as a result. In 1945, between 300 and 4,000 people, including in India, were killed by a tsunami on the Western coast of India, and this coast is possibly exposed to another event soon, potentially larger. The question is then: how do we protect the communities settled on the Western coast of India from a future tsunami? In the long term, only wise planning can reduce exposure, as early warning systems only mitigate the tsunami consequences. The answer to this question will be examined through a better scientific understanding of the tsunami hazard using Geology, numerical simulations, and Statistics. The land use and planning decisions, that should ideally prevent people from settling in zones prone to the dramatic impacts of possible future tsunamis, need to be implemented, strengthened and communicated efficiently based on the science at hand. There is currently no or very little planning for tsunami risk in these regions. These decisions will have to be made under great uncertainties and must reflect local attitudes towards risk, account for the economic value of decisions, and respect the ethical views of the authorities and the communities.

The three central aims will be to:
1. Analyse the tsunami risk arising from earthquakes and quantify the uncertainties regarding eventual coastal inundations that it causes.
2. Understand how urbanisation processes, and in particular land use and planning decisions, contribute to the impact of coastal inundation on communities
3. Assess the uncertainties regarding these impacts, the value put at risk by them and the information required by stakeholders to develop mitigation and response strategies that reflect these considerations.

This project will take an interdisciplinary approach that brings together natural scientific modelling of hazards, social analysis of urban development dynamic, and decision-theoretic (including ethical) evaluation of the aims of mitigation policies. In this first short-term study, we will focus on two coastal towns in India, with the intent of laying down the foundations for a more ambitious future study. By doing an initial study of this kind we can assess the feasibility of in depth mitigation planning that is sensitive to scientific uncertainty and to community values, and trial a multidisciplinary approach to managing natural hazards.

As witnessed by recent tsunami events in Japan and the Indian Ocean, we know the potential for loss of lives and destruction is massive when a tsunami strikes densely populated areas. The Western coast of India is potentially at risk of large tsunami impact, a fact which is has not entered into development policy and practice.

Our project aims at identifying and quantifying statistically possible tsunami hazard for the Western coastal communities of India, due to tsunamis generated by earthquakes on the Makran subduction zone, that may include giant earthquakes comparable to Indian Ocean Tsunami of 2004 on the east and southern coasts and much larger than the most recent historical large Makran earthquake in 1945, which affected the west coast, including Mumbai.

The Mumbai metropolitan region has grown from around 5 million to 25 million people since 1945, with a large concentration of poor population on the coast and living on low-lying reclaimed land. Such density poses massive evacuation issues due to the lack of infrastructure and preparedness. Many smaller towns and rural areas along the Arabian sea coast of India have also seen large population increases, such as Navi Mumbai and Daman (possible case study areas) and present similar problems of development close to the coast.

The project engages two of the leading Indian research institutes in this field, Indian Institute of Science (IISc) and the Indian Institute for Human Settlements (IIHS) with UK researchers from UCL and LSE as a 'foundation' phase to support initial collaborative activities across the natural sciences, social sciences and humanities with the potential to develop further research together. Both IISc and IIHS have strong Indian-based networks on hazards research (IISc) and on development policy and disaster management (IIHS). The knowledge developed in this project will used to engage with the networks that IISc and IIHS are part of.

The purpose of this project is to develop a better understanding of tsunami risks (and its uncertainties) and to communicate these risks to the users and beneficiaries of such information. Users of the information include national and state disaster management authorities, urban development authorities and national urban development programmes, such as Smart City Mission and Atal mission for renewal and urban and urban transformation (AMRUT), as well as port authorities and state planning departments. Engagement with these users will be multi-faceted, 1) field work in the case study areas including stakeholder interviews 2) a stakeholder consultation and workshop for users and beneficiaries hosted by IIHS, and 3) a policy brief communicating the risks of tsunami on the western coast developed by bringing together scientific knowledge with policy communication expertise from the project team.