Paleoseismologie

Paleoseismology, or paleoseismologie in French, is the scientific study of past earthquakes through geological records to infer the size, timing, and frequency of seismic events on faults. It integrates field mapping, trenching across fault zones, stratigraphic analysis, and dating techniques to reconstruct ground-rupturing earthquakes that extend beyond written archives.

In the field, researchers identify fault traces, scarps, and displaced sedimentary layers. Trench investigations reveal a vertical exposure through deformed deposits, enabling identification of individual rupture events, measurements of slip, and construction of an earthquake chronology. Dating methods such as radiocarbon, optically stimulated luminescence dating (OSL), and paleomagnetic data provide age constraints. Geophysical surveys and sedimentology aid interpretation of preserved structures. By combining multiple lines of evidence, scientists estimate recurrence intervals and, in some cases, maximum magnitudes for faults.

Applications include informing seismic hazard analyses and probabilistic seismic hazard assessments, contributing to building codes and risk mitigation. Paleoseismology helps identify active faults, reconstruct rupture histories, and refine estimates of fault slip rates and earthquake probabilities. The approach applies to various fault types, including strike-slip, normal, and reverse faults, as well as plate-boundary and intraplate settings.

Limitations include dating uncertainties, preservation bias, and incomplete exposure that can complicate interpretations. Surficial processes such as sedimentation, erosion, or vegetation growth may obscure evidence, and correlations between events on neighboring faults may be uncertain.