QuakeScout
Magnitude4.7

Reviewed by USGS11y ago

M4.7 earthquake in South Sandwich Islands region

Wednesday, March 18, 2015, 02:46:05 UTC · 56.156°S, 27.038°W

A magnitude 4.7 earthquake struck in South Sandwich Islands region on Wednesday, March 18, 2015, 02:46:05 UTC, at a depth of 57.9 km (shallow). It is the strongest earthquake within 300 km since an M5.4 on February 28, 2015.

Magnitude
4.7
Light · mb
Depth
58 km
Shallow
Felt reports
0
Max intensity I
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

169 tons of TNT

That is about 1/89 of the Hiroshima bomb. A magnitude 5.0 releases about 3 times more energy.

Tectonic setting

84 km

from the nearest mapped plate boundary, between the Sandwich and South American plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.

Depth: shallow

58 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 2 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M4.9 on April 4, 2015. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

M3M4M51h6h1d3d7d14d30dMainshock M4.7
Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.
  1. 4.4South Sandwich Islands region11y ago · 44 km SW of this epicenter
  2. 4.9South Sandwich Islands region11y ago · 13 km W of this epicenter

Regional history

Past M5+ earthquakes within 300 km

USGS lists 1,074 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

  1. 8.11929 South Sandwich Islands EarthquakeJune 27, 1929 · 169 km NW of this epicenter
  2. 7.8South Sandwich Islands regionMay 26, 1964 · 42 km SW of this epicenter
  3. 7.2South Sandwich Islands regionDecember 27, 1991 · 111 km E of this epicenter
  4. 7.1South Sandwich Islands regionSeptember 8, 1961 · 27 km SW of this epicenter
  5. 6.9South Sandwich Islands regionAugust 18, 1930 · 71 km NW of this epicenter
  6. 6.9South Sandwich Islands regionSeptember 13, 1921 · 117 km NW of this epicenter
  7. 6.9South Sandwich Islands regionSeptember 6, 2004 · 149 km NW of this epicenter
  8. 6.9South Sandwich Islands regionJune 29, 2014 · 113 km NW 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. The most severe:

  1. 1929M8.1

    South Sandwich Islands

    27 Jun 1929 · 169 km away

  2. 1961M7.7

    South Sandwich Islands

    5 Sep 1961 · 205 km away

  3. 1961M7.7

    South Sandwich Islands

    8 Sep 1961 · 19 km away

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

Nearby trackers

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