Reviewed by USGSIndonesia35y ago
M4.2 earthquake 75 km N of Luwuk, Indonesia
Saturday, June 29, 1991, 20:50:42 UTC · 0.272°S, 122.794°E
A magnitude 4.2 earthquake struck 75 km N of Luwuk, Indonesia on Saturday, June 29, 1991, 20:50:42 UTC, at a depth of 169.7 km (intermediate).
- Magnitude
- 4.2
- Light · mb
- Depth
- 170 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
30 tons of TNT
That is about 1/500 of the Hiroshima bomb. A magnitude 5.0 releases about 16 times more energy.
Tectonic setting
156 km
from the nearest mapped plate boundary, between the Molucca Sea and Sunda plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.
Depth: intermediate
170 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 1 M2.5+ earthquake within 50 km in the following 30 days; the largest was M4.7 on July 20, 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 523 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 · 28 km N of this epicenter
- 7.8160 km W of Gorontalo, IndonesiaJanuary 22, 1905 · 163 km NW of this epicenter
- 7.875 km NNW of Gorontalo, IndonesiaApril 18, 1990 · 162 km N of this epicenter
- 7.7120 km NE of Palu, IndonesiaMay 19, 1938 · 252 km W of this epicenter
- 7.579 km NNW of Gorontalo, IndonesiaJune 20, 1991 · 163 km N of this epicenter
- 7.433 km NW of Gorontalo, IndonesiaNovember 8, 1941 · 112 km N of this epicenter
- 7.491 km SW of Gorontalo, IndonesiaAugust 6, 1984 · 37 km NW of this epicenter
- 7.1156 km NW of Gorontalo, IndonesiaJanuary 11, 1913 · 207 km NW of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 17 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 190 recorded deaths. The most severe:
- 1845M7.0
N Sulawesi: Menado, Tikala, Tomohon
8 Feb 1845 · 300 km away · intensity IX
118 deathsModerate damage ($1–5M)tsunami
- 1927M6.2
Sulawesi: Donggala
1 Dec 1927 · 237 km away · intensity VII
50 deathsSevere damage ($5–24M)tsunami
- 1938M7.7
Sulawesi Island
19 May 1938 · 252 km away · intensity IX
17 deathsSevere damage ($5–24M)tsunami
- 1990M7.6
Minahassa Peninsula: Bolaang-Gorontalo
18 Apr 1990 · 162 km away
3 deathsSevere damage ($5–24M)
- 1983M6.1
Central Sulawesi
25 Oct 1983 · 266 km away · intensity VII
2 deathsModerate damage ($1–5M)
- 1991M7.5
Minahassa: Gorontalo, Mamado
20 Jun 1991 · 163 km away · intensity VI
Severe damage ($5–24M)
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.