Reviewed by USGSIndonesia35y ago
M4.6 earthquake 134 km N of Gorontalo, Indonesia
Friday, September 20, 1991, 12:53:07 UTC · 1.751°N, 123.009°E
A magnitude 4.6 earthquake struck 134 km N of Gorontalo, Indonesia on Friday, September 20, 1991, 12:53:07 UTC, at a depth of 31.5 km (shallow). It is the strongest earthquake within 300 km since an M4.8 on September 14, 1991.
- Magnitude
- 4.6
- Light · mb
- Depth
- 32 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 earthquake
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
37 km
from the nearest mapped plate boundary, between the Molucca Sea and Sunda plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
32 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 has not published any M2.5+ earthquake within 50 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 530 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.11939 Sulawesi EarthquakeDecember 21, 1939 · 198 km S of this epicenter
- 7.8160 km W of Gorontalo, IndonesiaJanuary 22, 1905 · 200 km SW of this epicenter
- 7.875 km NNW of Gorontalo, IndonesiaApril 18, 1990 · 65 km S of this epicenter
- 7.7228 km SW of Sarangani, PhilippinesJune 11, 1972 · 261 km NE of this epicenter
- 7.579 km NNW of Gorontalo, IndonesiaJune 20, 1991 · 66 km S of this epicenter
- 7.433 km NW of Gorontalo, IndonesiaNovember 8, 1941 · 115 km S of this epicenter
- 7.491 km SW of Gorontalo, IndonesiaAugust 6, 1984 · 211 km S of this epicenter
- 7.2295 km SSE of Tabiauan, PhilippinesMarch 29, 1907 · 211 km N of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 18 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 123 recorded deaths. The most severe:
- 1845M7.0
N Sulawesi: Menado, Tikala, Tomohon
8 Feb 1845 · 207 km away · intensity IX
118 deathsModerate damage ($1–5M)tsunami
- 1990M7.6
Minahassa Peninsula: Bolaang-Gorontalo
18 Apr 1990 · 65 km away
3 deathsSevere damage ($5–24M)
- 1983M6.1
Central Sulawesi
25 Oct 1983 · 249 km away · intensity VII
2 deathsModerate damage ($1–5M)
- 1991M7.5
Minahassa: Gorontalo, Mamado
20 Jun 1991 · 66 km away · intensity VI
Severe damage ($5–24M)
- 1939M8.0
Centrtal Sulawesi: Kalo,Luwuk,Sula I
21 Dec 1939 · 195 km away
Moderate damage ($1–5M)tsunami
- 1983M6.0
Celebes: Minahassa: Tolitoli
16 Oct 1983 · 230 km away
Moderate damage ($1–5M)
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.