Type-I Edge-Localized Modes (ELMs) are events associated with H-mode tokamak operations during which about 10% of plasma energy is released from the pedestal region. The largest fraction of this energy is deposited onto the divertor target tiles by parallel transport along magnetic field lines. At JET, the spatial and temporal resolution of a new InfraRed (IR) thermography system monitoring the outer divertor target (1.7mm and 35 - 86ms, respectively) allows for an accurate study of the ELM induced non axisymmetric heat load patterns called here striations. These striations can be linked to toroidal inhomogeneities at the outer midplane which has been observed on other devices such as ASDEX Upgrade, MAST or DIII-D. Here we report analysis of these striations and associated toroidal mode number carried out over Type-I ELMy H-Mode plasmas with BT /IP in the range 1.6T-3.3T/1.5MA-2.5MA and mainly NBI input power from 8 to 20MW.