The ground under San Juan, Puerto Rico — measured by the Global Seismographic Network (IRIS/USGS) station IU SJG 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 |
|---|---|---|---|
| M5.0 | 22 km SSE of Güiria, Venezuela | 1970-01-01 00:00 UTC | 957 km |
| M4.8 | 0 km SW of Cepitá, Colombia | 1970-01-01 00:00 UTC | 1,464 km |
| M4.7 | 20 km SW of Sandy Point Town, Saint Kitts and Nevis | 1970-01-01 00:00 UTC | 346 km |
| M4.1 | 1970-01-01 00:00 UTC | 1,463 km | |
| M4.1 | 1970-01-01 00:00 UTC | 87 km | |
| M4.0 | 1970-01-01 00:00 UTC | 1,051 km | |
| M4.0 | 1970-01-01 00:00 UTC | 246 km | |
| M3.9 | 1970-01-01 00:00 UTC | 137 km | |
| M3.9 | 1970-01-01 00:00 UTC | 292 km | |
| M3.9 | 1970-01-01 00:00 UTC | 258 km |
| Mag | Where | When | Distance |
|---|---|---|---|
| M7.7 | 12 km WSW of Pitaloza Arriba, Panama | 1970-01-01 00:00 UTC | 1,968 km |
| M7.0 | 191 km ENE of Nagqu, China | 1970-01-01 00:00 UTC | 14,008 km |
| M6.9 | 76 km NE of Ozernovskiy, Russia | 1970-01-01 00:00 UTC | 11,163 km |
| M6.9 | 197 km WNW of Port-Olry, Vanuatu | 1970-01-01 00:00 UTC | 14,490 km |
| M6.8 | central Mid-Atlantic Ridge | 1970-01-01 00:00 UTC | 5,505 km |
| M6.7 | central Mid-Atlantic Ridge | 1970-01-01 00:00 UTC | 5,435 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.