How do gravitational interactions with Jupiter send asteroid fragments toward Earth?

Gravitational interactions with Jupiter send asteroid fragments toward Earth primarily through the mechanism of mean-motion resonances, which create regions of orbital depletion known as Kirkwood gaps.12

When an asteroid fragment in the main belt enters a resonance—such as the 3:1 resonance, where the object completes three orbits for every one of Jupiter’s—it experiences regular, repeated gravitational "nudges" from the planet. Because these forces are applied in a consistent direction, they cause the asteroid's orbit to become chaotic. Over a period of approximately one million years, these perturbations shift the asteroid's perihelion (its closest point to the Sun) inside Earth’s orbit, effectively injecting the fragment into an Earth-crossing path.324

While these resonances clear material from the belt, a constant supply of new fragments is maintained through collisions between asteroids and the Yarkovsky effect, which causes smaller debris to drift into these resonant zones.13