  The $\tau$-Herculids (IAU shower number #61 TAH) is a minor meteor shower
associated with comet 73P/Schwassmann-Wachmann 3, a Jupiter-Family comet that
disintegrated into several fragments in 1995. As a consequence of the nucleus
break-up, possible increased meteor rates were predicted for 2022. On May
30-31, observation networks around the world reported two distinct peaks of TAH
activity, around solar longitudes 69.02{\deg} and 69.42{\deg}. This work
examines the encounter conditions of the Earth with meteoroids ejected from 73P
during the splitting event and on previous perihelion passages. Numerical
simulations suggest that the main peak observed in 2022 was caused by
meteoroids ejected from the splitting nucleus with four times the typical
cometary gas expansion speed. High-resolution measurements performed with the
Canadian Automated Meteor Observatory indicate that these meteoroids are
fragile, with estimated bulk densities of 250 kg/m$^3$. In contrast with the
main peak, the first TAH activity peak in 2022 is best modelled with trails
ejected prior to 1960. We find that ordinary cometary activity could have
produced other TAH apparitions observed in the past, including in 1930 and
2017. The extension of our model to future years predicts significant returns
of the shower in 2033 and 2049.
