How does the prospect of future disaster shape the governance of the city? Istanbul is located in an active fault zone with a long history of devastating earthquakes, and the majority of its fifteen million inhabitants live and work in potentially unsound buildings. The deadly earthquakes that struck the Marmara region in 1999 and eastern Turkey in 2011 generated widespread anxiety about Istanbul’s vulnerability to a similar disaster, and gave rise to a range of state and nongovernmental efforts to prepare for the coming earthquake. This paper examines the technopolitical project of securing Istanbul’s seismic cityscape against the threat of future earthquakes through efforts to measure, map, and mitigate earthquake risk. Drawing on two years of ethnographic fieldwork with engineers, architects, seismologists, disaster preparedness planners, activists, and local residents, I explore the production of earthquake risk as both a technical calculation and a political category, one that enables particular forms of intervention in the built environment. I then trace the implementation and contestation of several such interventions, including building code enforcement, a mandatory earthquake insurance policy, and the ongoing “earthquake-focused urban renewal” process created by a controversial 2012 disaster risk reduction law. These projects intersect with the broader politics of urban transformation, environmental protection, and neoliberal restructuring of the economy that have become central to the clash between the ruling Justice and Development Party (AKP) government and the opposition movements that coalesced in the Gezi Park protests in Istanbul in 2013. In the paper, I argue that expert knowledge about risk is mobilized both by local and national authorities to justify their governance of urban environments, and by communities of activists and residents that seek to challenge state policy and practice.