landslide or flowing debris
 

I am in urgent need to know a quick & simple way to create landslide/ flowing debris and an explosion effect

Bit vague in what you want, it's also not going to be quick and simple (far from it if you want it to be realistic)

Explosion -> Particles from and omni emmitter with the particles emmiting particles (for the smoke) with fileds such as turbulance and gravity.

debris -> Instanced geometry on particels with fields and particle collision events (for bounce and dust etc)

Or Use maya fliuds for the explosion if you have unlimited (even harder).

there´s a tutorial on how to make a very simple explosion on the help file in maya. its in the fluids section. if you dont want to do it you could open up the visor.
i think its in window, general editors, visor.
there is a huge list of different things. like paint effects, hair, trees, fluids etc.. find the explosions sections there theres 5 or 6. (maybe more) explosions samples. just middle mouse drag them onto your work area.

how this can be of some help to you.

Thanks
 

Thanks i'll try what you've suggested and see how it goes