M6.9 earthquake 81 km NW of Maubara, Timor Leste

Thursday, July 4, 1991, 11:43:10 UTC · 8.099°S, 124.681°E

A magnitude 6.9 earthquake struck 81 km NW of Maubara, Timor Leste on Thursday, July 4, 1991, 11:43:10 UTC, at a depth of 28.8 km (shallow). It is the strongest earthquake within 300 km since an M6.9 on June 7, 1991.

Magnitude: 6.9; Strong · mwb
Depth: 29 km; Shallow
Felt reports: 0; Did You Feel It?
Est. shaking: VI; Strong (ShakeMap)
PAGER alert: None; Not issued
Tsunami: No flag; USGS feed

Outlined circle: this earthquakeDashed circle: 100 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

338 kilotons of TNT

That is about 22 times the Hiroshima bomb. It released about 708 times the energy of a magnitude 5.0.

Tectonic setting

47 km

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

Depth: shallow

29 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 14 M2.5+ earthquakes within 100 km in the following 30 days; the largest was M5.3 on July 5, 1991. 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 269 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 9 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 418 recorded deaths. The most severe:

1896
Timor: Alor Island
18 Apr 1896 · 18 km away · intensity VIII
250 deathsModerate damage ($1–5M)
1987M6.5
Timor: Pantar, Mount Sirung
26 Nov 1987 · 60 km away
125 deaths$5 million damagetsunami
1991M6.5
Timor: Kalabahi, Dili
4 Jul 1991 · 0 km away
28 deaths$8 million damage
1982M5.9
Flores Island: Eastern
25 Dec 1982 · 179 km away
13 deaths$1 million damagetsunami
1961M6.5
Flores: Endeh
16 Mar 1961 · 295 km away · intensity VIII
2 deathsModerate damage ($1–5M)
1814
Timor Island, Kupang, Kissar Island
1814 · 262 km away
Severe damage ($5–24M)tsunami

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

Nearby trackers