Helicorders are one of the ways we look at earthquakes and other seismic events. Information from our seismographs is sent back to the seismology lab and the signal is transfered onto paper. We currently have 8 helicorder drums set up in our lab, monotoring activity in Washington and Oregon, specifically the volcanoes in the area. The other seismograph signals we view on the computer.

Our seismographs pick up many different types of events. Along with earthquakes, our instruments can pick up rockfalls and rock quarry blasts. They also pick up interference and it occasionally is hard to distinguish a siesmic event from trees blowing in the wind. For an earthquake, we look for a signal that begins very abrubtly and gradually tapers out. A rock fall looks like a teardrop, starting small, getting bigger in the middle, and tapering off at the end. A signal that doesn't have these characteristics most likely interference. When viewing a seismogram record, up-ward lines represent the ground moving up, while downward lines signify downward motion.

Our instruments are so sensitive they can pick up earthquakes that occur around the world. Characteristics of these "teleseisms" are the spacing between upward and downward ground motion is wider than local events.

Rockfall                          Earthquake

Rockfall                          Earthquake

Data can also be seen using our webicorders. These operate just like helicorders and show the same information that we receive in the lab. The webicorders update every minute and operate and can be viewed by the public. We currently steam over 50 short-period and strong-motion seismometers into our webicorders. Many stations are located at schools throughout Washington and Oregon.

To view the webicorders click here.

Many steps go into analyzing the information that is received in the seismology lab. The most basic step is looking at the seismograms from our helicorders and double checking the computers are receiving all the events. We locate earthquakes and rockfalls by hand and compare our results with the computer's automatic event locations.

For a more indepth look at seismic analysis click here.