Starquake

Astronomers call the sudden changes in the neutron star starquakes. The energy released in a starquake is enormous and flows out from the star into the space surrounding it. After the 1969 starquake on the Crab pulsar, a wave of energy was seen to flow outwards, rippling through the centre of the Crab Nebula.

2000, Richard I. Epstein, Bennett Link, Starquake-Induced Glitches in Pulsars, Kwong-Sang Cheng H, F, Chau, K. L. Chan, K. C. Leung (editors), Stellar Astrophysics: Proceedings of the Pacific Rim Conference, page 96, Starquakes in slowing neutron stars drive matter toward the magnetic poles, distort the star's shape, and excite precession.

2000, Carl Sagan, Jerome Agel, Carl Sagan's Cosmic Connection: An Extraterrestrial Perspective [new edition of 1973, The Cosmic Connection], page 260, Should the core be solid, starquakes are expected — a shifting of the matter under enormous stress in the interior of the star. Such starquakes should produce a discontinuous change in the period of rotation of the neutron star. Such changes, called "glitches," are observed.