QuakeScout
Magnitude3.9

Reviewed by USGSIndia21y ago

M3.9 earthquake 100 km SW of Port Blair, India

Saturday, April 2, 2005, 19:36:39 UTC · 10.924°N, 92.214°E

A magnitude 3.9 earthquake struck 100 km SW of Port Blair, India on Saturday, April 2, 2005, 19:36:39 UTC, at a depth of 30.0 km (shallow).

Magnitude
3.9
Minor · 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

11 tons of TNT

That is about 1/1,410 of the Hiroshima bomb. A magnitude 5.0 releases about 45 times more energy.

Tectonic setting

36 km

from the nearest mapped plate boundary, between the Caribbean and Cocos 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 M5.0 on April 10, 2005. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

M3M4M51h6h1d3d7d14d30dMainshock M3.9
Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.
  1. 4.584 km SSW of Port Blair, India21y ago · 41 km E of this epicenter
  2. 4.7124 km SW of Port Blair, India21y ago · 25 km SW of this epicenter
  3. 5.0133 km SSW of Port Blair, India21y ago · 40 km S of this epicenter

Regional history

Past M5+ earthquakes within 300 km

USGS lists 263 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

  1. 8.043 km N of Bamboo Flat, IndiaJune 26, 1941 · 137 km N of this epicenter
  2. 6.8166 km NE of Bamboo Flat, IndiaJanuary 24, 1983 · 269 km NE of this epicenter
  3. 6.6Nicobar Islands, India regionDecember 26, 2004 · 228 km S of this epicenter
  4. 6.5152 km NNE of Bamboo Flat, IndiaSeptember 13, 2002 · 253 km N of this epicenter
  5. 6.5171 km S of Port Blair, IndiaApril 19, 1936 · 106 km SE of this epicenter
  6. 6.3273 km SSE of Port Blair, IndiaOctober 21, 1916 · 232 km SE of this epicenter
  7. 6.3Nicobar Islands, India regionOctober 25, 1970 · 273 km SE of this epicenter
  8. 6.3Nicobar Islands, India regionSeptember 15, 1964 · 247 km S of this epicenter

History · NOAA

Deadliest earthquakes in this area

NOAA’s significant-earthquake database lists 3 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 2 recorded deaths. The most severe:

  1. 2002M6.5

    Andaman Islands: Rongat, Diglipur,Ariel Bay

    13 Sep 2002 · 253 km away

    2 deathsModerate damage ($1–5M)tsunami

  2. 1941M8.0

    Andaman Islands,Madras; Sri Lanka: Colombo

    26 Jun 1941 · 122 km away

    Extreme damage ($25M+)tsunami

  3. 1881M7.9

    Andaman I,Nicobar I

    31 Dec 1881 · 268 km away

    Severe damage ($5–24M)tsunami

NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.

Nearby trackers

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