Fault Scarp Dating Tool - a MATLAB code for fault scarp dating using in-situ chlorine-36 supplemented with datasets of Yavansu and Kalafat faults

Abstract

We publish a MATLAB code used to analyze concentration profile of cosmogenic 36Cl accumulated in-situ through a rupture history of the fault scarps in western Turkey (Mozafari et al., 2019). The code is a version of the forward modeling Matlab code -Fault Scarp Dating Tool- (Tikhomirov, 2014). The code models a 36Cl profile accumulated in the fault scarp surface through a guessed rupture history, and compares the modeled and measured 36Cl profiles with statistical tests. Rupture histories are randomly generated in bounded solution space using Monte-Carlo method or optimized using Random Walk algorithm to achieve the best fit of the modeled and measured 36Cl profiles. The code has a user-friendly interface, a build-in help and an example of input data.

Determining Histories of Slip on Normal Faults With Bedrock Scarps Using Cosmogenic Nuclide Exposure Data

“…Bayesian techniques are often applied to deal with uncertainty associated with limited data (Amey et al, 2019;Bronk Ramsey, 2009;Montoya-Noguera & Wang, 2017). Several different Bayesian MCMC approaches have been developed for modeling cosmogenic data from fault scarps (Beck et al, 2018;Tesson & Benedetti, 2019;Tikhomirov et al, 2011). In this study, we prefer the modified version of the approach in Cowie et al (2017) because our primary aim is to identify and compare first-order variations in fault slip rate.…”

Seismic Activity of the Manisa Fault Zone in Western Turkey Constrained by Cosmogenic 36Cl Dating

“…We collected 87 samples, which covered approximately 7 m of the 12-m scarp surface height from the ground level; 36 samples were obtained from both MAN-A and MAN-B, and 15 samples from MAN-C. In addition, the fault scarp geometry parameters (i.e., scarp dip, scarp height, top surface dip, and colluvium dip, Figure 5) were precisely measured in the field (e.g., [22,27,37]. In comparison, Akçar et al [24] collected 44 samples along a ca.…”

“…To analyze the distribution of 36 Cl concentrations accumulated on the Manastır fault scarp (MAN) and reanalyze the dataset for the Mugırtepe fault scarp (MUG), we applied the computation code based on the Monte-Carlo method, which allows the reconstructions of the time-slip histories of normal fault scarps through two separate stages of database building and data simulation [37]. In the database-building stage, the chemical composition of the bedrock, sample positions, shielding of the scarp and colluvium are considered to calculate the production of the isotope in every sample depending on fixed slip step and rock erosion.…”

“…After identifying the most accurate number of events in terms of the lowest statistical criteria, we modeled the time-slip histories using minimum 100,000 simulations to achieve the best fit scenario based on one and two earthquake scenarios for the Manastır fault and one to three earthquake scenarios for the Mugırtepe fault. In the FSDT code [37] "Beginning of exposure" indicates the time when the 36 Cl starts to accumulate in the analyzed section of the fault scarp at depth, but it does not refer to any exposure and/or any seismic event. Thus, the analyzed strip is assumed to be still underground (e.g., covered by the colluvium) at the beginning of cosmogenic 36 Cl accumulation.…”

“…We focus on two fault scarps within the western part of the Manisa Fault Zone (MFZ), documented as one of the most seismically-damaged regions in history [3,48,55,[57][58]. Specifically, we applied the Fault Scarp Dating Tool (FSDT) computation code [37] to recover rupture histories of the Manastır and Mugırtepe faults (MAN and MUG in Figure 3, respectively) in the western segment of the active MFZ. We analyzed 87 samples from the Manastır fault surface and remodeled the cosmogenic 36 Cl concentrations already measured on the Mugırtepe fault surface [24].…”