Very strong mag. 6.5 earthquake - 167 km south of Obihiro, Hokkaido, Japan, on Saturday, April 30, 1983 at 14:03 GMT
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Very strong magnitude 6.5 earthquake at 30 km depth
1 Jan 00:00 UTC: First to report: USGS after 30 seconds.
Earthquake details
| Date & time | Apr 30, 1983 14:03:49 UTC |
| Local time at epicenter | |
| Status | Confirmed |
| Magnitude | 6.5 |
| Depth | 30.4 km |
| Epicenter latitude / longitude | 41.473°N / 143.764°E  (North Pacific Ocean, Japan) |
| Antipode | 41.473°S / 36.236°W |
| Shaking intensity | Strong shaking near epicenter |
| Felt | 0 reports |
| Primary data source | USGS (United States Geological Survey) |
| Nearest volcano | Shikaribetsu Group (207 km / 129 mi) |
| Nearby towns and cities | 150 km (93 mi) SE of Shizunai-furukawachō (pop: 22,400) | Show on map | Quakes nearby 167 km (104 mi) SSE of Obihiro (pop: 173,900) | Show on map | Quakes nearby 174 km (108 mi) SSW of Kushiro (pop: 183,600) | Show on map | Quakes nearby 175 km (109 mi) SSE of Otofuke (pop: 40,900) | Show on map | Quakes nearby 219 km (136 mi) ENE of Hachinohe (pop: 239,000) | Show on map | Quakes nearby 220 km (137 mi) SE of Tomakomai (pop: 174,800) | Show on map | Quakes nearby 264 km (164 mi) ENE of Aomori (pop: 298,400) | Show on map | Quakes nearby 266 km (165 mi) SE of Sapporo (pop: 1,883,000) | Show on map | Quakes nearby 296 km (184 mi) NE of Morioka (pop: 295,200) | Show on map | Quakes nearby 734 km (456 mi) NNE of Tokyo (pop: 8,336,600) | Show on map | Quakes nearby |
| Estimated seismic energy released | 3.5 x 1014 joules (98.6 gigawatt hours, equivalent to 84802 tons of TNT or 5.3 atomic bombs!) | about seismic energy |
Data for the same earthquake reported by different agencies
Info: The more agencies report about the same quake and post similar data, the more confidence you can have in the data. It takes normally up to a few hours until earthquake parameters are calculated with near-optimum precision.
| Mag. | Depth | Location | Source |
| 6.5 | 30 km | Hokkaido, Japan region | USGS |
User reports for this quake
User reports estimate the perceived ground shaking intensity according to the MMI (Modified Mercalli Intensity) scale.
Aftershocks
[More info]
Recorded aftershocks, latest first (9 quakes)
Date and time | Mag Depth | Location | Details |
| Oct 13, 1983 10:01 39 years ago | 5.5 30 km | 142 km S of Kushiro, Hokkaido, Japan | More |
| Jul 28, 1983 15:06 39 years ago | 5.5 63 km | 47 km SE of Shizunai-furukawachō, Hidaka-gun, Hokkaido, Japan | More |
| May 11, 1983 16:59 39 years ago | 4.5 87 km | Horoizumi-gun, 104 km S of Obihiro, Hokkaido, Japan | More |
| May 1, 1983 18:55 39 years ago | 4.5 60 km | 167 km S of Obihiro, Hokkaido, Japan | More |
| May 1, 1983 07:13 39 years ago | 5.0 48 km | 186 km S of Obihiro, Hokkaido, Japan | More |
| Apr 30, 1983 23:59 39 years ago | 4.7 68 km | 168 km S of Obihiro, Hokkaido, Japan | More |
| Apr 30, 1983 20:17 39 years ago | 4.6 45 km | 187 km S of Obihiro, Hokkaido, Japan | More |
| Apr 30, 1983 15:57 39 years ago | 5.1 51 km | 171 km S of Obihiro, Hokkaido, Japan | More |
| Apr 30, 1983 15:50 39 years ago | 4.5 70 km | 175 km S of Obihiro, Hokkaido, Japan | More |
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