The 2018 version of the Global Earthquake Model: Hazard component

Abstract

In December 2018, at the conclusion of its second implementation phase, the Global Earthquake Model (GEM) Foundation released its first version of a map outlining the spatial distribution of seismic hazard at a global scale. The map is the result of an extensive, joint effort combining the results obtained from a collection of probabilistic seismic hazard models, called the GEM Mosaic. Together, the map and the underlying database of models provide an up-to-date view of the earthquake threat globally. In addition, using the Mosaic, a synopsis of the current state-of-practice in modeling probabilistic seismic hazard at national and regional scales is possible. The process adopted for the compilation of the Mosaic adhered to the maximum extent possible to GEM’s principles of collaboration, inclusiveness, transparency, and reproducibility. For each region, priority was given to seismic hazard models either developed by well-recognized national agencies or by large collaborative projects involving local scientists. The version of the GEM Mosaic presented herein contains 30 probabilistic seismic hazard models, 14 of which represent national or sub-national models; the remainder are regional-scale models. We discuss the general qualities of these models, the underlying framework of the database, and the outlook for the Mosaic’s utility and its future versions.

Global dominance of tectonics over climate in shaping river longitudinal profiles

“…The spatial association of plate boundaries and river profile concavity suggests a strong tectonic control on river profiles. We quantitatively explore this possibility using three proxy measures of tectonic activity: mean river profile slope and two metrics of seismic risk (from the Global Earthquake Model [Pagani et al, 2020] and the Global Seismic Hazard Assessment Program [Giardini et al, 1999]). The global patterns in these tectonic proxies (Fig.…”

“…Here we compare Chen et al's global dataset of 333,502 river longitudinal profiles [Chen et al, 2019] with global datasets of climate, river slope, and seismic activity [Giardini et al, 1999;Trabucco & Zomer, 2009;Fick & Hijmans, 2017;Pagani et al, 2020] to test the relative importance of tectonics versus climate as global controls on river profile concavity. Following Chen et al [2019], we characterize river longitudinal profiles by their Normalized Concavity Index (NCI), a dimensionless measure of a river profile's median deviation from a straight line (see Methods, and Fig.…”

Probabilistic seismic risk assessment of India

“…In 2018, the Global Earthquake Model (GEM) released a first version of its open-source global seismic hazard map (Pagani et al, 2018), which was realized using the OpenQuake engine (Pagani et al, 2014; Silva et al, 2013). This model incorporated the work of Nath and Thingbaijam (2012) for the Indian subcontinent, as implemented by Ackerley (2016).…”

Potential impact of earthquakes during the 2020 COVID-19 pandemic

“…The hazard is expressed in terms of the PGA (as a fraction of g ) for a probability of exceedance of 10% in 50 years (equivalent to a 475 year return period) on rock (average shear-velocity down to 30 m - Vs30 = 760 m/s). A detailed description of how the global seismic hazard model was developed can be found in Pagani et al (2020).…”

“…The results regarding the displaced population (presumed to be more vulnerable to the virus) were used to estimate the potential increase in the number of cases and fatalities, considering different infection rates. Finally, to identify regions in the world where performing such simulations might be particularly important, the most recent data concerning the number of confirmed cases at the national or subnational level were combined with global seismic hazard and risk maps (Pagani et al, 2020; Silva et al, 2020) to produce a combined index. This index reflects directly areas with significant seismic hazard and/or risk and prevalence of COVID-19 cases.…”