Reviewed by USGSIndonesia41y ago
M5.3 earthquake 128 km WSW of Insrom, Indonesia
Thursday, November 21, 1985, 00:17:55 UTC · 1.694°S, 135.018°E
A magnitude 5.3 earthquake struck 128 km WSW of Insrom, Indonesia on Thursday, November 21, 1985, 00:17:55 UTC, at a depth of 33.0 km (shallow). It is the strongest earthquake within 300 km since an M6.0 on November 17, 1985.
- Magnitude
- 5.3
- Moderate · 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 earthquakeDashed circle: 75 km aftershock search area
In context
How big was it, and why here?
Energy released
1 kilotons of TNT
That is about 1/11 of the Hiroshima bomb. It released about 3 times the energy of a magnitude 5.0.
Tectonic setting
198 km
from the nearest mapped plate boundary, between the Birds Head and Caroline plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.
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 75 km
USGS lists 2 M2.5+ earthquakes within 75 km in the following 30 days; the largest was M6.0 on December 6, 1985. 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 178 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.21914 Biak EarthquakeMay 26, 1914 · 216 km E of this epicenter
- 7.955 km S of Biak, IndonesiaSeptember 12, 1979 · 114 km E of this epicenter
- 7.736 km NNE of Nabire, IndonesiaJanuary 13, 1916 · 170 km SE of this epicenter
- 7.65 km SW of Manokwari, IndonesiaApril 27, 1944 · 141 km NW of this epicenter
- 7.6138 km SW of Insrom, IndonesiaMay 27, 1947 · 19 km S of this epicenter
- 7.182 km SE of Biak, IndonesiaJune 22, 1957 · 175 km E of this epicenter
- 7.1127 km SE of Manokwari, IndonesiaNovember 17, 1985 · 13 km NW of this epicenter
- 7.196 km SSW of Nabire, IndonesiaJanuary 27, 1942 · 272 km S of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 10 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 375 recorded deaths. The most severe:
- 1864M7.8
Irian Jaya: Manokwari
23 May 1864 · 77 km away · intensity VII
250 deathsSevere damage ($5–24M)tsunami
- 1979M7.9
New Guinea: Irian Jaya
12 Sep 1979 · 114 km away
115 deathsSevere damage ($5–24M)tsunami
- 1985M6.3
New Guinea: Irian Jaya: Enarotali
15 Sep 1985 · 294 km away
10 deathsModerate damage ($1–5M)
- 1957M7.3
New Guinea: Irian Jaya
22 Jun 1957 · 221 km away
Severe damage ($5–24M)tsunami
- 1914M8.1
New Guinea: Irian Jaya: Japen
26 May 1914 · 214 km away · intensity IX
Moderate damage ($1–5M)tsunami
- 1985M7.1
New Guinea: Irian Jaya: Manokwari
17 Nov 1985 · 13 km away · intensity VIII
Limited damage (under $1M)
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.