Spatial correlation of ground motions in the 2016-2017 Central Italy seismic sequence

Schiappapietra, Erika and Douglas, John (2019) Spatial correlation of ground motions in the 2016-2017 Central Italy seismic sequence. In: SECED 2019 Conference, 2019-09-09 - 2019-09-10, University of Greenwich.

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Over the past decade, spatial correlation of earthquake ground motion has become increasingly important for seismic hazard and risk assessments, particularly when applied to portfolios of buildings or spatially distributed infrastructures. Indeed, not only do these studies require the estimation of ground motion intensity measures at multiple sites, but also the quantification of the correlation structure. Several spatial correlation models have been published and common findings suggest that intraevent correlation decreases quite rapidly with increasing separation distances. Nevertheless, significant differences among the proposed models exist, leading to large uncertainties in the assessed seismic risk. This suggests that different correlation estimation methods, earthquake type and magnitude, as well as region and local site conditions might play first-order roles in the observed differences. The aim of this study is to identify factors that influence the correlation structure of ground-motion measures and quantify the variability of spatial correlation among different events within the same region and with the same local site conditions. In order to investigate this, we carry out a thorough geostatistical analysis of the intra-event correlation structure, taking advantage of the 2016-2017 Central Italy seismic sequence database, which include nearly 1,600 records from nine Mw ≥ 5.0 events that occurred over a time period of five months. Our preliminary results could be used to improve seismic loss estimation as well as for more informed risk management and decision making in this region.