Answer:
El Nino is caused by the interaction between the surface of the ocean and the  atmosphere on top. It is the internal changes of volume of the ocean atmosphere system that tells when the start and end of the El Nino event will be. The physical process is hard and includes unstable air-sea interactions. The system is between warm and neutral conditions with a circle that lasts 3-4 years. Forces from volcano eruptions have nothing to do with El Nino.
Explanation:
