Reviewed by USGSSolomon Islands35y ago
M4.6 earthquake 42 km WNW of Buala, Solomon Islands
Tuesday, October 29, 1991, 02:32:58 UTC · 7.973°S, 159.243°E
A magnitude 4.6 earthquake struck 42 km WNW of Buala, Solomon Islands on Tuesday, October 29, 1991, 02:32:58 UTC, at a depth of 33.0 km (shallow). It is the strongest earthquake within 300 km since an M5.3 on October 15, 1991.
- 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 earthquakeDashed circle: 50 km aftershock search area
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
183 km
from the nearest mapped plate boundary, between the Pacific 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 50 km
USGS lists 1 M2.5+ earthquake within 50 km in the following 30 days; the largest was M4.7 on October 29, 1991. 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 257 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.8116 km NW of Kirakira, Solomon IslandsOctober 10, 1931 · 287 km SE of this epicenter
- 7.823 km SSE of Malango, Solomon IslandsApril 30, 1939 · 222 km S of this epicenter
- 7.685 km SE of Honiara, Solomon IslandsFebruary 7, 1984 · 264 km SE of this epicenter
- 7.5105 km ESE of Honiara, Solomon IslandsApril 20, 1977 · 271 km SE of this epicenter
- 7.566 km SE of Honiara, Solomon IslandsApril 20, 1977 · 245 km SE of this epicenter
- 7.5103 km SE of Honiara, Solomon IslandsApril 21, 1977 · 275 km SE of this epicenter
- 7.562 km SW of Malango, Solomon IslandsJanuary 25, 1926 · 232 km S of this epicenter
- 7.341 km ESE of Malango, Solomon IslandsFebruary 19, 1906 · 231 km S of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 16 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 64 recorded deaths. The most severe:
- 1977M6.8
Solomon Islands
20 Apr 1977 · 238 km away · intensity VI
34 deathsSevere damage ($5–24M)tsunami
- 1977M8.1
Solomon Islands
21 Apr 1977 · 275 km away · intensity VII
18 deathsSevere damage ($5–24M)tsunami
- 1939M7.9
Solomon Islands
30 Apr 1939 · 147 km away
12 deathsModerate damage ($1–5M)tsunami
- 1984M7.5
Guadalcanal
7 Feb 1984 · 264 km away · intensity VI
Moderate damage ($1–5M)
- 1926M6.9
Solomon Islands
16 Sep 1926 · 192 km away
Moderate damage ($1–5M)tsunami
- 1977M7.6
Solomon Islands
20 Apr 1977 · 245 km away · intensity VII
Limited damage (under $1M)tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.