Abstract
Probabilistic fault displacement hazard analysis provides a systematic approach to estimate the likelihood of occurrence and expected amount of surface displacement during an earthquake on-fault (principal fault rupturing) and off-fault (distributed rupturing). The methodology is based on for key parameters describing the probability of occurrence and the spatial distribution of the displacement both on and off-fault. In this work we concentrate on off-fault rupturing, and develop an original probability model for the occurrence of distributed ruptures and for the expected displacement distribution based on the compilation and reappraisal of surface ruptures from 15 historical crustal earthquakes of reverse kinematics, with magnitudes ranging from Mw 4.9 to Mw 7.9. We introduce a new ranking scheme to distinguish principal faults (rank 1) from simple distributed ruptures (rank 2), bending-moment (rank 21) and flexural-slip (rank 22) and triggered faulting (rank 3). We then used the rank 2 distributed ruptures with distances from the principal fault ranging from 5 m to 1500 m. To minimize bias due to the incomplete nature of the database, we propose a ‘slicing ' approach as an alternative to the 'gridding' approach. The 'slicing' approach is then combined with MonteCarlo simulations to model the dependence of the probability of occurrence and exceedance with the dimensions and position of the site of interest with respect to the principal fault, both along and across strike. We applied the probability model to a case-study in Finland to illustrate the applicability of the method given the limited extend of the available dataset. We finally suggest that probabilistic fault displacement hazard model will benefit by evaluating spatial distribution of distributed rupture in the light of spatial completeness of the input data, structural complexity and physics observables of the causative fault.
Highlights
Probabilistic fault displacement hazard analysis (PFDHA) is a method developed for characterizing the expected amount and distribution of co-seismic fault displacement at the surface
For the purpose of this work, we assume that an earthquake with magnitude m produces surface faulting on the principal fault rupturing (PF), and we focus on the third and fourth terms of Eq 1 which require analyzing the spatial distribution of distributed rupturing (DR), deriving the most suitable measure of the displacement components along DR from the data collected in the database, estimating the probability of DR and estimating the probability of exceedance of a target level of displacement
Surface displacement data of 15 well-studied reverse earthquakes were gathered in an uniform database and used to derive empirical parameters used for describing the probabilities and expected levels of surface displacement in future events
Summary
Probabilistic fault displacement hazard analysis (PFDHA) is a method developed for characterizing the expected amount and distribution of co-seismic fault displacement at the surface. The key element in surface rupturing analysis is the differentiation between the principal fault rupturing (PF), and distributed rupturing (DR). The PFDHA methodology was developed for normal faulting environments by the working group of Youngs et al (2003) and developed further for strike-slip faults by Petersen et al (2011). For the case of reverse faults, Moss and Ross (2011) worked on PF data whereas Takao et al (2013) worked on both strike-slip and reverse faults but using data only from Japanese earthquakes. In depth analysis of the DR data for reverse faulting earthquakes has not received much attention from the scientific community. The present work is a first step toward filling this gap
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
