Question

Locust, earthquake,flood, landslide,riot (odd man out) give reason

Answer 1

riot . because all others are natural disasters

Answer 2

Of course riot. Locust, earthquake, flood and landslide are naturally occurring disasters. Riot is caused mostly by communal tension.

It is  violent disturbance i.e. a public disturbance during which a group of angry people becomes noisy and out of control, often damaging property and acting violently.

In law, a riot is typically defined as a group of three or more persons disturbing the peace for private purposes. So, the answer will be riot.