  We show that Thurston's earthquake flow is strongly asymmetric in the sense
that its normalizer is as small as possible inside the group of orbifold
automorphisms of the bundle of measured geodesic laminations over moduli space.
(At the level of Teichm\"uller space, such automorphisms correspond to
homeomorphisms that are equivariant with respect to an automorphism of the
mapping class group.) It follows that the earthquake flow does not extend to an
$\mathrm{SL}(2,\mathbf{R})$-action of orbifold automorphisms and does not admit
continuous renormalization self-symmetries. In particular, it is not conjugate
to the Teichm\"uller horocycle flow via an orbifold map. This contrasts with a
number of previous results, most notably Mirzakhani's theorem that the
earthquake and Teichm\"uller horocycle flows are measurably conjugate.
