After an Earthquake
You have recorded something, is it an earthquake?
A large, distant earthquake will be recorded across the network
- Check other schools
- Using REV, compare your record to a seismic station near you
- View a nearby USArray station by entering your zip code
After 10-15 minutes, the parameters for a large event will be available from the USGS
- Check for an e-mail message from the USGS Earthquake Notification Service
- Confirm that an event occurred by checking the IRIS Seismic Monitor
- Look for event information on the USGS NEIC Recent Earthquake site
No, it isn’t an earthquake.
Do these signals disrupt display and are so common that they interfere with recording earthquakes? If so try to determine what the problem might be, and seek assistance. Check out the FAQ's or ask for help in our forum.
If the signal is not disruptive to the display… this is a chance for you and your students determine the source of these signals. REAL science! Does the signal recur? Is there a pattern to the time of day when the signal occurs? These are just a few of the questions you might consider as you begin your investigation.
Yes, it is an earthquake! We have time to discuss it now (or tomorrow)!
Items like magnitude, location and news reporting may contribute to this decision.
- Resources: IRIS Teachable Moments, CNN, BBC, Google
Step 1: Estimate the distance and the location.
Step 2: Determine the magnitude of the event.
Step 3: Record event into the station log.
Step 4: Share with others.
Yes, it is an earthquake! No time to discuss it.
- Visit the USGS web site and record the magnitude, distance, and origin time on a station catalog.
- Print a copy of the seismogram to post next to a world map.
- Student team or seismology club analyze the event and report to the class later.
- Extract event starting at the origin time and continuing through the surface waves and save as a .sac file. Upload the file to IRIS!
We heard about an earthquake, but it doesn't seem like we recorded it.
- Examine your helicorder record for some indication of the event after the time of the event. The first arrival, if it’s visible, may be 20 minutes after the origin time of the earthquake. The surface waves may not peak for an hour or more.
- For distant events, try filtering the helicorder record with a band pass filter from 12 to 25 seconds. The gain will need to be increased by about a factor of 10 at the same time.
- Use the USGS Travel Time Calculator to find the distance to your station and the expected arrival times
- If the event is not recorded on your system but comes booming in on all of the other AS-1 records that are posted on the web, then you possibly have a technical problem. Check out the FAQ's or ask for help in our forum.
