Reviewed by USGSIndonesia42y ago
M7.1 earthquake 190 km SSW of Sibolga, Indonesia
Saturday, November 17, 1984, 06:49:30 UTC · 0.197°N, 98.027°E
A magnitude 7.1 earthquake struck 190 km SSW of Sibolga, Indonesia on Saturday, November 17, 1984, 06:49:30 UTC, at a depth of 33.0 km (shallow). It is the strongest earthquake within 300 km since an M7.6 on December 28, 1935.
- Magnitude
- 7.1
- Major · mw
- Depth
- 33 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
674 kilotons of TNT
That is about 45 times the Hiroshima bomb. It released about 1,413 times the energy of a magnitude 5.0.
Tectonic setting
104 km
from the nearest mapped plate boundary, between the Sunda and Australian 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 200 km
USGS lists 4 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M5.3 on November 17, 1984. 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 128 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.6212 km W of Pariaman, IndonesiaDecember 28, 1935 · 58 km SE of this epicenter
- 7.0122 km W of Pariaman, IndonesiaMay 8, 1946 · 151 km SE of this epicenter
- 7.0102 km SW of Padangsidempuan, IndonesiaFebruary 4, 1971 · 92 km NE of this epicenter
- 6.9181 km SW of Sibolga, IndonesiaDecember 4, 1974 · 30 km NW of this epicenter
- 6.7214 km SW of Sibolga, IndonesiaMay 29, 1914 · 53 km W of this epicenter
- 6.768 km SE of Singkil, IndonesiaApril 1, 1921 · 178 km N of this epicenter
- 6.6142 km WNW of Pariaman, IndonesiaJanuary 2, 1936 · 108 km E of this epicenter
- 6.6150 km WNW of Pariaman, IndonesiaMay 24, 1952 · 103 km SE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 15 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 2,355 recorded deaths. The most severe:
- 1861M8.5
Lagundi, Simuk, Tello I
16 Feb 1861 · 145 km away · intensity IX
1,105 deathsModerate damage ($1–5M)tsunami
- 1861M7.0
Sw. Sumatra
9 Mar 1861 · 21 km away
950 deathsSevere damage ($5–24M)tsunami
- 1797M8.0
Sw. Sumatra
10 Feb 1797 · 110 km away · intensity IX
300 deathsModerate damage ($1–5M)tsunami
- 1843M7.3
Sw. Sumatra
5 Jan 1843 · 145 km away · intensity XI
Severe damage ($5–24M)tsunami
- 1935M7.9
N Sumatera: Batu I,Padang,Sibolga
28 Dec 1935 · 33 km away · intensity VIII
Moderate damage ($1–5M)tsunami
- 1971M7.1
Natal, Sibolga, Tarutung, Pasaman
4 Feb 1971 · 97 km away · intensity VI
Moderate damage ($1–5M)
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.