Axions from the Earth

The possibility of axion production in the Earth's interior due to natural radioactive decay is considered. Axions, or axion-like particles, could be created in nuclear disintegrations and deexitations of natural radionuclides present in the Earth's crust and mantle, as well as due to photon to axion conversion of the emitted gamma rays via the Primakoff effect. The estimated geo-axion production rates and fluxes on the Earth's surface are given along with the axion coupling to ordinary matter in the frame of the simple axion models as well as for axion-like particles with stronger couplings.