re: Now Closed: Everything you ever wanted to know about EARTHQUAKES

quote:

---

What's the seismic activity we (S. LA folks) need to be most concerned about?

---

Good question. Seismologists study earthquakes using seismometers, which track the movement of the land horizontally and vertically. Their read outs are seismographs. Seismic activity is anything that is picked up by the seismometers.


Tracking horizontal movement


Tracking vertical movement

All movement in earth is due to propagation of seismic waves: the result of particles bumping into particles. In the first post you can see the 3 different types of waves and how they move through the earth.

You make a P wave when you talk. You move air particles from your mouth to your neighbors ear.