Reviewed by USGSGuam33y ago
M4.6 earthquake 59 km ESE of Inarajan Village, Guam
Saturday, September 18, 1993, 20:03:46 UTC · 13.073°N, 145.257°E
A magnitude 4.6 earthquake struck 59 km ESE of Inarajan Village, Guam on Saturday, September 18, 1993, 20:03:46 UTC, at a depth of 83.3 km (intermediate). It is the strongest earthquake within 300 km since an M4.7 on September 14, 1993.
- Magnitude
- 4.6
- Light · mb
- Depth
- 83 km
- Intermediate
- 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
120 tons of TNT
That is about 1/126 of the Hiroshima bomb. A magnitude 5.0 releases about 4 times more energy.
Tectonic setting
66 km
from the nearest mapped plate boundary, between the Mariana and Pacific plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: intermediate
83 km
Intermediate-depth earthquakes usually break inside a plate that is sinking into the mantle. Shaking spreads over a wide area but is gentler at the epicenter than a shallow quake of the same size.
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 M5.8 on September 26, 1993. 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 354 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.832 km S of Inarajan Village, GuamAugust 8, 1993 · 50 km W of this epicenter
- 7.2265 km S of Merizo Village, GuamJanuary 28, 1931 · 259 km S of this epicenter
- 7.1261 km S of Merizo Village, GuamMay 9, 1917 · 257 km S of this epicenter
- 7.0176 km ESE of San Jose Village, Northern Mariana IslandsMay 18, 1913 · 238 km NE of this epicenter
- 7.098 km SSE of Inarajan Village, GuamDecember 9, 1909 · 81 km SW of this epicenter
- 7.032 km NNE of Yigo Village, GuamOctober 26, 1912 · 89 km N of this epicenter
- 6.446 km ENE of Yigo Village, GuamOctober 29, 1936 · 75 km N of this epicenter
- 6.4279 km S of Merizo Village, GuamMay 6, 1917 · 279 km SW of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 9 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1993M7.8
Tuman Bay, Apra Harbor
8 Aug 1993 · 50 km away · intensity IX
$250 million damagetsunami
- 1849M7.5
Guam
25 Jan 1849 · 235 km away · intensity IX
Severe damage ($5–24M)tsunami
- 1909M8.0
Guam
9 Dec 1909 · 70 km away · intensity VIII
Moderate damage ($1–5M)tsunami
- 1892M7.5
Guam
16 May 1892 · 235 km away · intensity VIII
Moderate damage ($1–5M)tsunami
- 1825
Ladrones Island
Apr 1825 · 235 km away · intensity VIII
Moderate damage ($1–5M)tsunami
- 1834
Agana
May 1834 · 235 km away
Moderate damage ($1–5M)
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.