Shear-wave attenuation in northeastern and eastern Iran and its application in source parameters estimation of the local and regional earthquakes
Bibliographic record
Abstract
SUMMARY The northeastern and eastern regions of Iran experience frequent seismic activity, with even moderate earthquakes posing significant risks. Despite this, attenuation characteristics and earthquake source properties in this region remain insufficiently understood. This study investigates shear-wave attenuation and its implications for earthquake source parameters by analysing 2853 vertical and horizontal seismograms from 294 local and regional earthquakes (M1.5–5.5) with epicentral distances of 10–500 km. Using the horizontal-to-vertical spectral ratio technique, we corrected site effects and derived a region-specific shear-wave inelastic attenuation model, expressed as Q(f) = 121f 0.60 for frequencies between 0.5 and 15 Hz. The derived Q model reveals strong frequency dependence and indicates significant seismic wave attenuation in the region. Our findings reveal three distinct attenuation regimes: rapid near-source decay (R−1.16) for direct waves (<70 km), stable amplitudes due to postcritical reflections (70–150 km), and slower decay (R−0.5) at greater distances dominated by the Lg phase (>150 km). Applying the derived attenuation model, we systematically estimated moment magnitude (MW), and stress drop for small-to-moderate earthquakes, revealing significant heterogeneity in stress drops (0.1–100 MPa, average 5.1 MPa). While stress drop values exhibited a strong dependence on magnitude, we noted that this breakdown in self-similarity may have been influenced by limited data bandwidth and neglect of near-surface attenuation. Notably, stress drops in the intraplate region south of 36°N were more than twice as high as those in the northern interplate zone, highlighting a critical consideration for seismic hazard forecasting and designing resilient infrastructure. In addition to the fact that areas containing earthquakes with relatively large stress drops are likely to be regions of comparatively high tectonic stress, higher stress drop earthquakes radiate more high-frequency energy, leading to stronger ground shaking which in turn can result in potentially greater structural damage, widespread liquefaction and landslides. This study provides the first comprehensive database of moment magnitude and stress drop values for small-to-moderate earthquakes in the region and extends existing attenuation models to longer distances (up to 500 km). These results improve our understanding of shear-wave attenuation and its role in earthquake hazard analysis, contributing essential data for regional seismic risk assessment and ground-motion modelling.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".