Peak ground accelerations from large (M ≥ 7.2) shallow crustal earthquakes: a comparison with predictions from eight recent ground-motion models

Abstract

Strong-motion data from large (M C 7.2) shallow crustal earthquakes invariably make up a small proportion of the records used to develop empirical ground motion prediction equations (GMPEs). Consequently GMPEs are more poorly constrained for large earthquakes than for small events. In this article peak ground accelerations (PGAs) observed in 38 earthquakes worldwide with M C 7.2 are compared with those predicted by eight recent GMPEs. Well over half of the 38 earthquakes were not considered when deriving these GMPEs but the data were identified by a thorough literature review of strong-motion reports from the past 60 years. These data are provided in an electronic supplement for future investigations on ground motions from large earthquakes. The addition of these data provides better constraint of the between-event ground-motion variability in large earthquakes. It is found that the eight models generally provide good predictions for PGAs from these earthquakes, although there is evidence for slight underor over-prediction of motions by some models (particularly for M [ 7.6). The betweenevent variabilities predicted by most models match the observed variability, if data from two events (2001 Bhuj and 2005 Crescent City) that are likely atypical of earthquakes in active regions are excluded. For some GMPEs there is evidence that they are over-predicting PGAs in the near-source region of large earthquakes as well as over-predicting motions on hard rock. Overall, however, all the considered models, despite having been derived using limited data, provide reliable predictions of PGAs in the largest crustal earthquakes.Electronic supplementary material The online version of this article

Capturing Geographically-Varying Uncertainty in Earthquake Ground Motion Models or What We Think We Know May Change

“…Currently if a GMPE is based on a single event for M>7 then the additional uncertainty is the same as if a GMPE is based on many hundreds of earthquakes for that magnitude range. A recent study by Douglas and Boore (2017) suggests that the epistemic uncertainty in ground motions in the M 7+ bins is lower than could have been thought given the limited data used to constrain GMPEs in that magnitude range.…”

Evaluation of the Predictive Performance of Regional and Global Ground Motion Predictive Equations for Shallow Active Regions in Pakistan

“…The dataset consists of 147 records with Mw between 4.1 and 7.7 and distances between 8 and 466 km. The datasets were retrieved only in terms of the PGA of the time histories, from the NCEG network (5 data), from Shah et al [4] (128 data) and from the Douglas and Boore [15] paper (14 data). The focal mechanisms were extracted from the Global CMT catalog for 17 earthquakes, and for the rest, a reverse fault mechanism was assumed based on the prevalent faults where the epicenters were located.…”

A New Method for the Evaluation of GMPEs

“…Denklemin oluşturulmasında ki esas amacın, deprem dalgalarının yayılmasını modellemek ve yapıların karşılaşabileceği yer hareketi büyüklüklerini hesaplamak olduğu ve deprem dalgalarına yakınlık ne kadar artarsa, yapıların maruz kalacağı deprem etkilerinin büyüklüğünün de o kadar artacağı göz önüne alınırsa, denklemlerin özellikle maruziyet mesafesine göre daha hassas olmaları beklenir. Ancak hali hazırda geliştirilen denklemlerin böyle bir önceliği ve hassasiyeti olmadığı gibi, zaten denklemlerin geliştirilebilmesi için yerel ölçekte oluşturulan veri tabanlarının da ağırlıklı büyük depremlerin kısa mesafe etkilerini yansıtacak şekilde oluşturulması birçok yer için mümkün değildir [2]. Hâlihazırda kuvvetli yer hareketi modellerinin tamamı büyük depremleri kapsamakla birlikte [1], yıkıcı depremlerin büyük ve yakın mesafelerden etki ettiği gerçeği karşısında, bahsi geçen denklemlerin de aslında amaca tam olarak hizmet edip etmediği sorgulanabilir.…”