A Global Set of Subduction Zone Earthquake Scenarios and Recurrence Intervals Inferred From Geodetically Constrained Block Models of Interseismic Coupling Distributions

The past 100 years have seen the occurrence of five M-W >= 9 earthquakes and 94 M-W >= 8 earthquakes. Here we assess the potential for future great earthquakes using inferences of interseismic subduction zone coupling from a global block model incorporating both tectonic plate motions and earthquake cycle effects. Interseismic earthquake cycle effects are represented using a first-order quasistatic elastic approximation and include similar to 10(7) km(2) of interacting fault system area across the globe. We use estimated spatial variations in decadal-duration coupling at 15 subduction zones and the Himalayan range front to estimate the locations and magnitudes of potential seismic events using empirical scaling relationships relating coupled area to moment magnitude. As threshold coupling values increase, estimates of potential earthquake magnitudes decrease, but the total number of large earthquakes varies non-monotonically. These rupture scenarios include as many as 14 recent or potential M-W >= 9 earthquakes globally and up to 18 distinct M-W >= 7 events associated with a single subduction zone (South America). We also combine estimated slip deficit rates and potential event magnitudes to calculate recurrence intervals for large earthquake scenarios, finding that almost all potential earthquakes would have a recurrence time of less than 1,000 years. Plain Language Summary Earthquake forecasting is a fundamental goal of earth science. Forecasts are often based on patterns of past earthquakes in space and time but can be augmented with information from global positioning system (GPS) measurements of how Earth's surface moves in response to plate tectonic processes. In this study, we use results from a tectonic and earthquake cycle model based on GPS measurements to suggest the locations and magnitudes of potential earthquakes on 16 of the world's largest faults. Along these faults, two tectonic plates are coupled, or stuck together, to varying degrees: on some portions, the two plates slide freely past each other, and in other regions, the two plates are stuck, so the nearby portions of the plates themselves undergo distortion, which can be tracked using GPS. Studies of recent earthquakes suggest that the region of the fault that was stuck together prior to the earthquake is where the slip took place. With this in mind, we use a model of global fault coupling to find regions where additional great earthquakes may occur. We suggest that nearly all of the world's subduction zones, as well as the fault beneath the Himalayas, could produce a magnitude 9 or greater earthquake.