it is a kind of seismic wave that travels fast and increases its speed with depth?

The seismic wave you are referring to is a P-wave, or primary wave. P-waves are compressional waves that can travel through solids, liquids, and gases, and they are the fastest type of seismic wave, typically increasing in speed as they move deeper into the Earth due to higher pressure and density. Their ability to propagate through various materials makes them essential for understanding the Earth's internal structure and for seismic exploration.