M6.1 earthquake 165 km WNW of Tobelo, Indonesia

Wednesday, March 18, 1987, 00:22:49 UTC · 2.114°N, 126.571°E

A magnitude 6.1 earthquake struck 165 km WNW of Tobelo, Indonesia on Wednesday, March 18, 1987, 00:22:49 UTC, at a depth of 29.7 km (shallow). It is the strongest earthquake within 300 km since an M6.2 on February 16, 1987.

Magnitude: 6.1; Strong · mw
Depth: 30 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: 100 km aftershock search area

In context

How big was it, and why here?

Energy released

21 kilotons of TNT

That is about the energy of the Hiroshima bomb. It released about 45 times the energy of a magnitude 5.0.

Tectonic setting

13 km

from the nearest mapped plate boundary, between the Birds Head and Sunda plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.

Depth: shallow

30 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 100 km

USGS lists 9 M2.5+ earthquakes within 100 km in the following 30 days; the largest was M5.1 on April 16, 1987. 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 895 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 21 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 2,965 recorded deaths. The most severe:

1856
Sangihe Pulau (Volcanic)
2 Mar 1856 · 210 km away
2,806 deathsSevere damage ($5–24M)tsunami
1845M7.0
N Sulawesi: Menado, Tikala, Tomohon
8 Feb 1845 · 204 km away · intensity IX
118 deathsModerate damage ($1–5M)tsunami
1855
Maluku: Ternate Island
14 Jul 1855 · 167 km away · intensity IX
34 deathsModerate damage ($1–5M)
1932M7.7
Sulawesi: Kakas,Langowan,Poso,Tondano
14 May 1932 · 207 km away · intensity VII
7 deathsSevere damage ($5–24M)tsunami
1858M7.3
N. Moluccas Islands
13 Dec 1858 · 139 km away
Severe damage ($5–24M)tsunami
1889M8.0
N. Moluccas Islands
6 Sep 1889 · 129 km away
Moderate damage ($1–5M)tsunami

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

Nearby trackers