Reviewed by USGSIndonesia35y ago
M5.4 earthquake 86 km NNW of Gorontalo, Indonesia
Friday, June 21, 1991, 12:14:16 UTC · 1.277°N, 122.819°E
A magnitude 5.4 earthquake struck 86 km NNW of Gorontalo, Indonesia on Friday, June 21, 1991, 12:14:16 UTC, at a depth of 26.9 km (shallow). It is the strongest earthquake within 300 km since an M5.6 on June 20, 1991.
- Magnitude
- 5.4
- Moderate · mw
- Depth
- 27 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: 75 km aftershock search area
In context
How big was it, and why here?
Energy released
2 kilotons of TNT
That is about 1/8 of the Hiroshima bomb. It released about 4 times the energy of a magnitude 5.0.
Tectonic setting
79 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
27 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 75 km
USGS lists 4 M2.5+ earthquakes within 75 km in the following 30 days; the largest was M5.4 on June 21, 1991. 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 536 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 · 144 km S of this epicenter
- 7.8160 km W of Gorontalo, IndonesiaJanuary 22, 1905 · 152 km SW of this epicenter
- 7.875 km NNW of Gorontalo, IndonesiaApril 18, 1990 · 11 km SE of this epicenter
- 7.7120 km NE of Palu, IndonesiaMay 19, 1938 · 293 km SW of this epicenter
- 7.579 km NNW of Gorontalo, IndonesiaJune 20, 1991 · 10 km S of this epicenter
- 7.433 km NW of Gorontalo, IndonesiaNovember 8, 1941 · 61 km S of this epicenter
- 7.491 km SW of Gorontalo, IndonesiaAugust 6, 1984 · 155 km S of this epicenter
- 7.2295 km SSE of Tabiauan, PhilippinesMarch 29, 1907 · 265 km N of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 19 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 140 recorded deaths. The most severe:
- 1845M7.0
N Sulawesi: Menado, Tikala, Tomohon
8 Feb 1845 · 227 km away · intensity IX
118 deathsModerate damage ($1–5M)tsunami
- 1938M7.7
Sulawesi Island
19 May 1938 · 293 km away · intensity IX
17 deathsSevere damage ($5–24M)tsunami
- 1990M7.6
Minahassa Peninsula: Bolaang-Gorontalo
18 Apr 1990 · 11 km away
3 deathsSevere damage ($5–24M)
- 1983M6.1
Central Sulawesi
25 Oct 1983 · 219 km away · intensity VII
2 deathsModerate damage ($1–5M)
- 1991M7.5
Minahassa: Gorontalo, Mamado
20 Jun 1991 · 10 km away · intensity VI
Severe damage ($5–24M)
- 1939M8.0
Centrtal Sulawesi: Kalo,Luwuk,Sula I
21 Dec 1939 · 143 km away
Moderate damage ($1–5M)tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.