The ground under Tucson, United States — measured by the Global Seismographic Network (IRIS/USGS) station IU TUC 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 |
|---|---|---|---|
| M4.0 | 1970-01-01 00:00 UTC | 603 km | |
| M4.0 | 1970-01-01 00:00 UTC | 677 km | |
| M4.0 | 1970-01-01 00:00 UTC | 1,354 km | |
| M3.8 | 1970-01-01 00:00 UTC | 776 km | |
| M3.8 | 1970-01-01 00:00 UTC | 631 km | |
| M3.7 | 1970-01-01 00:00 UTC | 621 km | |
| M3.6 | 1970-01-01 00:00 UTC | 734 km | |
| M3.6 | 1970-01-01 00:00 UTC | 603 km | |
| M3.6 | 1970-01-01 00:00 UTC | 592 km | |
| M3.6 | 1970-01-01 00:00 UTC | 595 km |
| Mag | Where | When | Distance |
|---|---|---|---|
| M7.7 | 12 km WSW of Pitaloza Arriba, Panama | 1970-01-01 00:00 UTC | 4,142 km |
| M7.0 | 191 km ENE of Nagqu, China | 1970-01-01 00:00 UTC | 12,374 km |
| M6.9 | 76 km NE of Ozernovskiy, Russia | 1970-01-01 00:00 UTC | 7,362 km |
| M6.9 | 197 km WNW of Port-Olry, Vanuatu | 1970-01-01 00:00 UTC | 10,259 km |
| M6.8 | central Mid-Atlantic Ridge | 1970-01-01 00:00 UTC | 10,159 km |
| M6.7 | central Mid-Atlantic Ridge | 1970-01-01 00:00 UTC | 10,084 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.