Reviewed by USGSIndia region21y ago
M4.2 earthquake in Nicobar Islands, India region
Friday, September 23, 2005, 00:04:48 UTC · 8.013°N, 91.818°E
A magnitude 4.2 earthquake struck in Nicobar Islands, India region on Friday, September 23, 2005, 00:04:48 UTC, at a depth of 30.0 km (shallow).
- Magnitude
- 4.2
- Light · mb
- Depth
- 30 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
0 km
from the nearest mapped plate boundary, between the Indian and Burma plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
30 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 M5.3 on October 5, 2005. 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 425 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.2284 km WNW of Sabang, IndonesiaDecember 26, 2004 · 176 km SE of this epicenter
- 7.2Nicobar Islands, India regionJuly 24, 2005 · 42 km E of this epicenter
- 7.0190 km WNW of Sabang, IndonesiaMay 17, 1955 · 262 km SE of this epicenter
- 6.8238 km WNW of Sabang, IndonesiaJanuary 20, 1917 · 214 km SE of this epicenter
- 6.6Nicobar Islands, India regionApril 7, 1973 · 126 km S of this epicenter
- 6.6Nicobar Islands, India regionDecember 26, 2004 · 114 km NE of this epicenter
- 6.6249 km NW of Sabang, IndonesiaMarch 5, 1921 · 212 km E of this epicenter
- 6.5253 km WNW of Sabang, IndonesiaNovember 21, 1907 · 218 km SE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 5 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1881M7.9
Andaman I,Nicobar I
31 Dec 1881 · 88 km away
Severe damage ($5–24M)tsunami
- 1982M6.3
Little Nicobar Island
20 Jan 1982 · 268 km away · intensity VIII
Moderate damage ($1–5M)
- 2005M7.2
Andaman Islands, Nicobar Islands
24 Jul 2005 · 42 km away
Limited damage (under $1M)
- 1847
Little Nicobar Island
31 Oct 1847 · 217 km away · intensity X
Limited damage (under $1M)tsunami
- 1955M7.3
Little Nicobar Island
17 May 1955 · 294 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.