M7.8 earthquake 75 km NNW of Gorontalo, Indonesia

Wednesday, April 18, 1990, 13:39:19 UTC · 1.186°N, 122.857°E

A magnitude 7.8 earthquake struck 75 km NNW of Gorontalo, Indonesia on Wednesday, April 18, 1990, 13:39:19 UTC, at a depth of 25.7 km (shallow). It is the strongest earthquake within 300 km since an M8.1 on December 21, 1939.

Magnitude: 7.8; Major · mw
Depth: 26 km; Shallow
Felt reports: 0; Did You Feel It?
Est. shaking: VII; Very strong (ShakeMap)
PAGER alert: None; Not issued
Tsunami: No flag; USGS feed

Outlined circle: this earthquakeDashed circle: 200 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

7.6 megatons of TNT

That is about 502 times the Hiroshima bomb. It released about 15,849 times the energy of a magnitude 5.0.

Tectonic setting

77 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

26 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 200 km

USGS lists 81 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M6.5 on April 19, 1990. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.

Regional history

Past M5+ earthquakes within 300 km

USGS lists 457 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

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 140 recorded deaths. The most severe:

1845M7.0
N Sulawesi: Menado, Tikala, Tomohon
8 Feb 1845 · 224 km away · intensity IX
118 deathsModerate damage ($1–5M)tsunami
1938M7.7
Sulawesi Island
19 May 1938 · 292 km away · intensity IX
17 deathsSevere damage ($5–24M)tsunami
1990M7.6
Minahassa Peninsula: Bolaang-Gorontalo
18 Apr 1990 · 0 km away
3 deathsSevere damage ($5–24M)
1983M6.1
Central Sulawesi
25 Oct 1983 · 222 km away · intensity VII
2 deathsModerate damage ($1–5M)
1939M8.0
Centrtal Sulawesi: Kalo,Luwuk,Sula I
21 Dec 1939 · 133 km away
Moderate damage ($1–5M)tsunami
1983M6.0
Celebes: Minahassa: Tolitoli
16 Oct 1983 · 201 km away
Moderate damage ($1–5M)

NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.

Nearby trackers