 Solution

Excavate across the mapped fault scarp, approximately perpendicular to its strike, at a site where young sediments record and preserve deformation. On cleaned trench walls log bedding, soil horizons, shear zones, fissure fills, buried surfaces and colluvial wedges. Correlate the same marker beds across the fault before reconstructing individual displacements.

Look for event horizons, not merely a stack of sediments:

In the drawing, A was faulted in event 1; W1 accumulated; B buried and stabilized that surface. Event 2 displaced A, W1 and B, after which W2 accumulated and C sealed the fault tip. Thus A records two events, B one and C none. This combination of offset and sealing relationships is stronger evidence than identifying two wedge-shaped units alone.

Bracket event ages with multiple samples just below and above the event horizons. Suitable short-lived organic material can be dated by radiocarbon dating; optically stimulated luminescence dating can constrain deposition of appropriate mineral grains. Reworked old charcoal, younger roots, incomplete bleaching, erosional gaps and time elapsed between rupture and wedge deposition must enter the age interpretation. For calendar dates, $t_{\mathrm{youngest}\mathrm{cut}}<t_{\mathrm{event}}<t_{\mathrm{oldest}\mathrm{seal}}$ only when those deposits genuinely bracket the rupture; a radiocarbon age in years before present reverses the numerical ordering.^[ref]

One earthquake can generate several debris pulses and wedges; repeated earthquakes may reuse one strand without leaving separable deposits. Erosion, bioturbation, nondeposition, lateral facies changes and upward-dying splays can hide events or mimic terminations. Confirm relationships on both trench walls and, when possible, in adjacent exposures. The result is a minimum supported event sequence with age intervals, not an assumption of perfectly periodic recurrence or one earthquake per wedge.