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 6 helicorder drums set up in our lab, monitoring activity in Washington and Oregon. 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, rock quarry blasts, a person's footsteps, and various forms of interference. 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 does not have these characteristics is most likely interference. When viewing a seismograph 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. When these show up on our records, we call them teleseisms. Characteristics of these teleseisms are the larger spacing between the upward and downward ground motion, which looks much wider than that of local events.

Rockfall               Earthquake

Quarry Blast                   Teleseism

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 can be viewed by the public. We currently stream 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.