Reviewed by USGS22y ago
M4.2 earthquake in Pacific-Antarctic Ridge
Monday, August 2, 2004, 06:06:54 UTC · 63.288°S, 166.518°W
A magnitude 4.2 earthquake struck in Pacific-Antarctic Ridge on Monday, August 2, 2004, 06:06:54 UTC, at a depth of 10.0 km (shallow).
- Magnitude
- 4.2
- Light · mb
- Depth
- 10 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- —
- No ShakeMap
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeDashed circle: 50 km aftershock search area
In context
How big was it, and why here?
Energy released
30 tons of TNT
That is about 1/500 of the Hiroshima bomb. A magnitude 5.0 releases about 16 times more energy.
Tectonic setting
52 km
from the nearest mapped plate boundary, between the Pacific and Antarctic plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
10 km
Shallow earthquakes (under 70 km) produce the strongest surface shaking for their size, so they are the ones most likely to cause damage near the epicenter.
Did You Feel It?
Where it was felt
No “Did You Feel It?” reports have been published for this event yet. If you felt it, you can add your report on the USGS website.
I felt it — report to USGS ↗USGS PAGER estimate
Who was exposed to shaking
USGS publishes PAGER impact estimates for significant earthquakes, usually within an hour. No PAGER estimate is available for this event.
After the main event
Aftershocks within 50 km
USGS lists 3 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M5.1 on August 3, 2004. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 21 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 6.2Pacific-Antarctic RidgeJuly 1, 1965 · 150 km E of this epicenter
- 6.1Pacific-Antarctic RidgeApril 10, 1967 · 58 km SW of this epicenter
- 6.0Pacific-Antarctic RidgeAugust 1, 2004 · 31 km S of this epicenter
- 5.9Pacific-Antarctic RidgeSeptember 12, 1997 · 112 km E of this epicenter
- 5.9Pacific-Antarctic RidgeNovember 21, 1999 · 101 km E of this epicenter
- 5.8Pacific-Antarctic RidgeAugust 4, 1979 · 261 km E of this epicenter
- 5.6Pacific-Antarctic RidgeSeptember 21, 1999 · 54 km SW of this epicenter
- 5.6Pacific-Antarctic RidgeJuly 31, 2004 · 44 km E of this epicenter