Major earthquakes that cause considerable damage and losses are a constant reminder to politicians and decision makers that the reduction of seismic risk and increased resilience of urban areas are essential, both for the well-being and safety of the local populations, and also for maintaining global financial and economic balance. This is even more important considering the global urban population growth that we now face, and the concentration of wealth and modern infrastructure within cities. In general, the efforts that are required to define seismic hazard maps are usually uniformly distributed across a region. Therefore, the seismic hazard in the most exposed areas, such as urban environments, is not sufficiently integrated in terms of the detail and the scale of analysis. Focusing on urban areas for the prediction of seismic ground motion caused by natural or induced seismicity, and of the responses, vulnerability and protection of civil structures, lifelines and infrastructure are, therefore, two critical topics in the reduction of seismic risk for the increasingly urbanised global population.
The tectonic hazard has neither increased nor decreased in recent decades; only the vulnerability and exposure of the communities involved have changed. According to the World Health Organisation, the urban population in 2014 accounted for 54% of the total global population, which was up from 34% in 1960, and is predicted to continually grow annually by approximately 1.5% to 1.6% per year between 2015 and 2030. As a result, the casualties that will arise due to earthquakes are expected to reach about 2.8 million by 2100. Indeed, because of the long return periods of the largest high-consequence earthquakes, and because few urban areas in their current configuration have yet to suffer such major events, Jackson noted that the greatest earthquake disasters are yet to come. Europe has a long history of destructive earthquakes with Balkan and Mediterranean countries being at higher risk of earthquakes than other areas in Europe. With seismic hotspots across Europe, even a moderate earthquake can have devastating effects on urban environments and economy, especially in densely populated areas hosting critical structures and infrastructures, wealth and goods.
Contrary to the case of tectonic events, a constant rate of potentially damaging earthquakes cannot be relied upon in the case of induced seismicity. Such events are strongly dependent on human activity and can be caused, for instance, by reservoirs, withdrawal of trapped fluids and gases, and more recently, injection of fluids into the subsurface. Although still under debate, there is growing evidence that massive wastewater injections have caused sharp increases in seismicity, as exemplified in central Oklahoma, USA . Moreover, recent studies have provided evidence that early 20th century earthquakes in the USA were induced by oil production and/or injection of wastewater, and Hough and Page provided evidence for a causative relationship between major damaging Californian earthquakes and the initial oil boom in the Los Angeles urban area. The recent increase in human-caused earthquakes in the central USA and Canada make it important to understand the "full context" of how, where and why earthquakes are induced, and the nature of the induced ground motion and human and economic losses. In Europe, where potential extraction sites are typically closely located to, or even within urban areas, this issue has to be addressed to provide robust guidelines to industry, regulators and society at large.
This URBASIS grant will use the basic concepts and unifying ideas of seismic hazard, earthquake engineering and seismic risk assessment to move the physics of seismology and engineering seismology into research areas such as induced-seismicity risk analysis and urban seismology, where there will undoubtedly be social impact and economic applications. URBASIS will create a refocusing of earthquake engineering and engineering seismology into these emergent and important multi-scale problems, and by promoting close collaboration between physicists, seismologists and engineers, it will enrich and empower the existing communities by bringing sophisticated numerical and theoretical methods to the fore in urban seismology. The relevance of URBASIS for practical implementation of urban seismology concepts will be further underpinned by the development of a comprehensive framework for treating unavoidable issues such as the earthquake hazard associated with natural and induced seismicity, wave propagation in complex media, risk forecasting and decision making.
Finally, the URBASIS project aims to provide a multi- disciplinary training platform for Early-Strage Researchers (ESR) in order to develop their individual project and to promote their entrepreneurship and their employability toward the academic, private and insurance or decision-making sector. High-quality supervision of the ESR will be ensured through the international recognition of the URBASIS partners.
