How does an underwater earthquake cause a tsunami?

How does an underwater earthquake cause a tsunami?

Keywords search terms: earthquake formation, P wave, S wave, tsunami, earthquake travel, analyzing earthquakes.essay should do the following things:
    discuss how the different types of waves are formed and describe how the waves travel
    explain how scientists use waves to track and analyze earthquakes
    cover recent events involving earthquakes and/or tsunamis that illustrate the points made in your explanation