Proceedings of the 12th International INQUA meeting on paleoseismology, active tectonic and archaeoseismology

Unit 7 against the scarp face. The third event E3 displaced Unit 6 and juxtaposed Unit-6 and Unit- 7 along fault F3. Based on the age of Unit-7, we suggest that the E3 would have occurred after 6.0±0.7 ka (sample no. MF11, Fig. 3). E3 is followed by the deposition of Units 8 and 9 against the scarp face. The most-recent event in the trench, displaced Unit 7 and juxtaposed Unit 7 and Unit 8. Based on the crosscutting relationship and geochronology, we suggest that E4 occurred after the deposition of Unit-9, after 3.6±0.9 ka (sample no. MF9, Fig. 3). D I S C U S S I O N A N D C O N C L U S I O N Along the Marquesado Fault, we present evidence of at least four seismic events spanning back to 17-19 ka. The most recent event occurred around 3.6±0.9 ka, the penultimate event around 6.0±0.7 ka, antepenultimate event around 10.2±1 ka, and the oldest event after 17-19 ka. The age timing of the events helped us constraint recurrence interval which varies approximately from 3.5 ka between E4&E3, 4 ka between E3&E2, and 2.9 ka between E2&E1, with an average recurrence interval of 3.4 ka between seismic events. Based on paleoseismic investigation, it is probable that the Marquesado Fault has not produced any surface rupture since 3.6±0.9 ka, surpassing its recurrence interval of 3.4 ka. Fig. 3: Trench log of the southwall of the Marquesado trench, showing 9 units, defomed by the at least four events. The units are identified based on varying clast-size, fabric texture. The prominent evidence of events are based on the presence of shear fabric, juxtaposition of varying units, and folding of units.