  We prove two related results. The first is an ``Earthquake Theorem'' for
closed hyperbolic surfaces with cone singularities where the total angle is
less than $\pi$: any two such metrics in are connected by a unique left
earthquake. The second result is that the space of ``globally hyperbolic'' AdS
manifolds with ``particles'' -- cone singularities (of given angle) along
time-like lines -- is parametrized by the product of two copies of the
Teichm\"uller space with some marked points (corresponding to the cone
singularities). The two statements are proved together.
