Iranian Journal of Geophysics

Iranian Journal of Geophysics

Constructing a multi-source ground motion data bank: methodology for cleaning and integrating Iran, Turkey, and PEER records

Articles in Press

Document Type : Research Article

Authors
Farzad Mahdavianfard 1
Mehdi Zare 2
Hamid Zafarani 2
Mojtaba Labibzadeh 3
1 Ph.D., Student, International Institute of Earthquake Engineering and Seismology, Tehran, Iran
2 Professor, International Institute of Earthquake Engineering and Seismology, Tehran, Iran
3 Associate Professor, Chamran University, Ahwaz, Iran
10.30499/ijg.2026.558421.1733
Abstract
The primary objective of this study is to provide a comprehensive evaluation of the challenges and methodologies involved in processing and refining earthquake ground-motion records, ultimately leading to the development of a reliable and unified database. The data used in this research were compiled from three different sources, records from Iran, Turkey, and the international PEER database, covering the period from 1935 to 2024. The Iranian strong-motion dataset includes 1,913 time histories from 189 earthquakes with moment magnitudes greater than 5 and recorded at distances up to 80 km. The additional datasets consist of 576 time histories from 99 Turkish earthquakes (AFAD), as well as 116 shallow crustal earthquakes from around the world obtained from the PEER database, which together provide 3,114 time histories with moment magnitudes greater than 5 and recorded at distances of up to 30 km. In recent years, large databases such as NGA-West2 have provided a set of processed or semi-processed records that both provide a model for processing and are used as a source of records that can be used in regional studies. In many seismic regions, such as Iran, despite significant seismic activity, access to high-quality strong ground motion records, especially at high magnitudes (Mw > 6.5) and near-fault distances, remains limited. This data shortage causes response spectrum models or ground motion prediction relationships to be based on a small set of local data that are not statistically reliable. To overcome this limitation, one effective solution is to combine domestic (Iranian) data with records from neighboring countries, such as Turkey, and with international databases, such as PEER NGA-West2. During the record-processing workflow, the data were first cleaned, and incomplete or corrupted records (such as those with gaps or instrument malfunction) were removed. An initial filter was then applied to eliminate unwanted noise. Subsequently, baseline correction was performed to remove non-physical cumulative drifts in the velocity and displacement components. Furthermore, the signal-to-noise ratio (SNR) was estimated as the final criterion for record selection. Therefore, records with low SNR (weak signal or high noise) are eliminated. These steps lead to an integrated database of high-quality ground-motion records from these three sources, which can be used in future studies, such as seismic hazard analysis, seismic design, and numerical modeling. We included only healthy and valid records in the analysis to ensure the final results were sufficiently reliable. The processing results show that, within the short- and mid-period ranges, the differences between displacement response spectra are negligible, indicating limited sensitivity of the spectra to the processing approach used. The combination of baseline correction and low-frequency filtering appears to be the only approach that produces stable spectra across the entire period range, free from artificial long-period amplification. Additionally, applying a low-pass filter alongside a high-pass filter can effectively protect long-period displacement responses from non-physical oscillations.
 
Keywords
Processing
baseline correction
butterworth filter
strong ground motion records
displacement response spectrum

Subjects

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Iranian Journal of Geophysics

Articles in Press, Accepted Manuscript
Available Online from 06 March 2026

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