The M9.1 earthquake that occurred in Tohoku, Japan on March 11, 2011 was the largest earthquake ever recorded in Japan and the 4th largest in the world that we have experienced. It produced a catastrophic tsunami that killed over 10,000 people and left many more homeless. It also caused severe damage to the infrastructure of Japan and is quoted as the most costly natural disaster in history, estimated at ~$235 billion. An earthquake of this size generates seismic waves that travel all across the planet and are detected by seismometers.
In this section, we will listen to seismic data at the 3 stations shown in the map below. They represent close, intermediate, and far distances from the earthquake epicenter.
The Background Noise
Before we listen to the earthquakes, we will first listen to the background noise levels at one of the three stations, P39A, in Salisbury, MO.
- What do you notice about the background noise? Are there any dominant frequencies?