Reviewed by USGS107y ago
M8.1 earthquake 1920 Vanuatu Earthquake
Monday, September 20, 1920, 14:39:03 UTC · 19.982°S, 168.478°E
A magnitude 8.1 earthquake struck 1920 Vanuatu Earthquake on Monday, September 20, 1920, 14:39:03 UTC, at a depth of 25.0 km (shallow). No earthquake of this size or larger appears within 300 km in the USGS catalog since 1900.
- Magnitude
- 8.1
- Great · mw
- Depth
- 25 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- VI
- Strong (ShakeMap)
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeColoured lines: estimated shaking intensity (USGS ShakeMap)
In context
How big was it, and why here?
Energy released
21 megatons of TNT
That is about 1,367 times the Hiroshima bomb. It released about 43,152 times the energy of a magnitude 5.0.
Tectonic setting
32 km
from the nearest mapped plate boundary, between the New Hebrides and Australian plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
25 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 400 km
USGS has not published any M2.5+ earthquake within 400 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 13 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.828 km ESE of Isangel, VanuatuJune 16, 1910 · 120 km E of this epicenter
- 7.663 km NW of Isangel, VanuatuOctober 14, 1913 · 110 km NE of this epicenter
- 7.1175 km SE of Isangel, VanuatuMarch 30, 1910 · 216 km SE of this epicenter
- 6.946 km NE of Isangel, VanuatuJune 30, 1905 · 143 km NE of this epicenter
- 6.943 km N of Port-Vila, VanuatuFebruary 4, 1910 · 294 km N of this epicenter
- 6.986 km NE of Isangel, VanuatuMarch 25, 1912 · 184 km NE of this epicenter
- 6.872 km WSW of Isangel, VanuatuMay 1, 1910 · 25 km NE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 15 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 26 recorded deaths. The most severe:
- 1875M8.1
Loyalty Islands: Lifou Island
28 Mar 1875 · 3 km away
26 deathsSevere damage ($5–24M)tsunami
- 1901M7.9
Loyalty Islands
9 Aug 1901 · 274 km away
Moderate damage ($1–5M)tsunami
- 1920M8.1
Loyalty Islands
20 Sep 1920 · 0 km away
Limited damage (under $1M)tsunami
- 1878M7.5
Tanna Island
10 Jan 1878 · 109 km away
Limited damage (under $1M)tsunami
- 1913M8.1
Vanuatu Islands
14 Oct 1913 · 77 km away
- 1878M8.0
Vanuatu Islands
11 Feb 1878 · 109 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.