QuakeScout
Magnitude4.6

Reviewed by USGSIndonesia40y ago

M4.6 earthquake 160 km NW of Tobelo, Indonesia

Tuesday, April 21, 1987, 01:52:38 UTC · 2.582°N, 126.845°E

A magnitude 4.6 earthquake struck 160 km NW of Tobelo, Indonesia on Tuesday, April 21, 1987, 01:52:38 UTC, at a depth of 33.0 km (shallow). It is the strongest earthquake within 300 km since an M5.1 on April 16, 1987.

Magnitude
4.6
Light · mb
Depth
33 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

26 km

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

Depth: shallow

33 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 928 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

  1. 7.8161 km SE of Sarangani, PhilippinesApril 1, 1936 · 194 km N of this epicenter
  2. 7.790 km NE of Tobelo, IndonesiaSeptember 8, 1966 · 184 km E of this epicenter
  3. 7.7148 km SE of Tondano, IndonesiaMay 14, 1932 · 267 km SW of this epicenter
  4. 7.7121 km E of Bitung, IndonesiaAugust 10, 1968 · 141 km SW of this epicenter
  5. 7.6101 km SE of Sarangani, PhilippinesDecember 16, 1910 · 249 km N of this epicenter
  6. 7.6223 km ESE of Sarangani, PhilippinesJanuary 30, 1969 · 238 km N of this epicenter
  7. 7.564 km NNW of Ternate, IndonesiaJune 25, 1907 · 143 km S of this epicenter
  8. 7.5146 km NW of Ternate, IndonesiaAugust 14, 1986 · 95 km S of this epicenter

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:

  1. 1856

    Sangihe Pulau (Volcanic)

    2 Mar 1856 · 192 km away

    2,806 deathsSevere damage ($5–24M)tsunami

  2. 1845M7.0

    N Sulawesi: Menado, Tikala, Tomohon

    8 Feb 1845 · 253 km away · intensity IX

    118 deathsModerate damage ($1–5M)tsunami

  3. 1855

    Maluku: Ternate Island

    14 Jul 1855 · 205 km away · intensity IX

    34 deathsModerate damage ($1–5M)

  4. 1932M7.7

    Sulawesi: Kakas,Langowan,Poso,Tondano

    14 May 1932 · 267 km away · intensity VII

    7 deathsSevere damage ($5–24M)tsunami

  5. 1858M7.3

    N. Moluccas Islands

    13 Dec 1858 · 199 km away

    Severe damage ($5–24M)tsunami

  6. 1889M8.0

    N. Moluccas Islands

    6 Sep 1889 · 188 km away

    Moderate damage ($1–5M)tsunami

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

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