The ground under Corvallis, United States — measured by the Global Seismographic Network (IRIS/USGS) station IU COR and redrawn here every 15 minutes. A thin band means a quiet ground; a tall spike is a passing earthquake, near or on the other side of the planet.
| Mag | Where | When | Distance |
|---|---|---|---|
| M4.8 | 97 km W of Petrolia, CA | 1970-01-01 00:00 UTC | 495 km |
| M4.2 | 1970-01-01 00:00 UTC | 316 km | |
| M4.2 | 1970-01-01 00:00 UTC | 456 km | |
| M4.0 | 1970-01-01 00:00 UTC | 960 km | |
| M4.0 | 1970-01-01 00:00 UTC | 566 km | |
| M3.9 | 1970-01-01 00:00 UTC | 919 km | |
| M3.9 | 1970-01-01 00:00 UTC | 416 km | |
| M3.8 | 1970-01-01 00:00 UTC | 1,198 km | |
| M3.5 | 1970-01-01 00:00 UTC | 1,341 km | |
| M3.5 | 1970-01-01 00:00 UTC | 906 km |
| Mag | Where | When | Distance |
|---|---|---|---|
| M7.7 | 12 km WSW of Pitaloza Arriba, Panama | 1970-01-01 00:00 UTC | 5,804 km |
| M7.0 | 191 km ENE of Nagqu, China | 1970-01-01 00:00 UTC | 10,671 km |
| M6.9 | 76 km NE of Ozernovskiy, Russia | 1970-01-01 00:00 UTC | 5,636 km |
| M6.9 | 197 km WNW of Port-Olry, Vanuatu | 1970-01-01 00:00 UTC | 9,671 km |
| M6.8 | central Mid-Atlantic Ridge | 1970-01-01 00:00 UTC | 11,133 km |
| M6.7 | central Mid-Atlantic Ridge | 1970-01-01 00:00 UTC | 11,054 km |
Waves from a large earthquake reach this station minutes later — up to about 20 minutes from the far side of the Earth. Look for a spike in the helicorder at that time.