Minor
Magnitude 3+
Description
Often felt, but rarely causes damage.
Felt by many indoors; hanging objects swing.
Recent Earthquakes at This Level
| Mag | Location | Time |
|---|---|---|
| 3.0 | 52 km NNW of Karluk, Alaska | 11 hours, 41 minutes ago |
| 3.1 | 210 km W of Port Orford, Oregon | 14 hours, 14 minutes ago |
| 3.1 | 22 km S of Funny River, Alaska | 1 day, 13 hours ago |
| 3.27360818475327 | 21 km N of Searles Valley, CA | 1 day, 23 hours ago |
| 3.2 | 75 km E of Cantwell, Alaska | 2 days, 9 hours ago |
| 3.0 | 55 km ENE of Pedro Bay, Alaska | 2 days, 11 hours ago |
| 3.4 | 31 km SSE of Skwentna, Alaska | 2 days, 14 hours ago |
| 3.57 | 3 km SE of Meno, Oklahoma | 2 days, 17 hours ago |
| 3.57 | 35 km S of Sandy Valley, Nevada | 2 days, 23 hours ago |
| 3.37822 | 7 km NNE of Delta, B.C., MX | 2 days, 23 hours ago |
| 3.45636011376983 | 5 km NE of Delta, B.C., MX | 3 days, 15 hours ago |
| 3.07695866299346 | 8 km NNE of Delta, B.C., MX | 3 days, 16 hours ago |
| 3.0 | 51 km E of Chignik, Alaska | 3 days, 17 hours ago |
| 3.4 | 86 km W of Akhiok, Alaska | 3 days, 17 hours ago |
| 3.1 | 63 km SE of Pedro Bay, Alaska | 4 days, 4 hours ago |
| 3.49953983436486 | 9 km NNE of Delta, B.C., MX | 4 days, 10 hours ago |
| 3.46 | 104 km NNW of San Antonio, Puerto Rico | 5 days, 3 hours ago |
| 3.28 | 10 km S of Santa Isabel, Puerto Rico | 5 days, 5 hours ago |
| 3.7 | 17 km SSW of Weston, Colorado | 5 days, 10 hours ago |
| 3.2 | 29 km WNW of Nikiski, Alaska | 5 days, 12 hours ago |
Frequently Asked Questions
The magnitude scale is logarithmic because earthquake energy varies over an enormous range. Each whole-number increase represents about 31.6 times more energy released. A linear scale would be impractical because a M9.0 earthquake releases roughly 1 billion times more energy than a M3.0 earthquake.
Magnitude measures the total energy released at an earthquake's source — each earthquake has one magnitude. Intensity (Modified Mercalli scale) measures the effects at a specific location — the same earthquake can have different intensities at different distances. A M7.0 earthquake might be MMI IX near the epicenter but only MMI III 200 km away.
Theoretically, maximum magnitude is limited by the length of faults that can rupture simultaneously. The longest subduction zones could produce earthquakes up to about M10, but no fault system on Earth is long enough to exceed this. The largest recorded earthquake was M9.5 (Chile, 1960).
A magnitude 7.0 earthquake releases approximately 1,000 times more energy than a magnitude 5.0 earthquake. Each whole-number step represents 31.6 times more energy, so two steps (5 to 7) is 31.6 x 31.6 = approximately 1,000 times. In terms of amplitude, each step is 10 times larger.
A foreshock is a smaller earthquake that precedes a larger mainshock in the same area — though it can only be identified as such after the mainshock occurs. An aftershock follows the mainshock and is caused by stress adjustments along and near the ruptured fault. Aftershock sequences can last days to years depending on mainshock magnitude.