Reviewed by USGSPhilippines50y ago
M5.6 earthquake 39 km SSE of Panubigan, Philippines
Friday, October 22, 1976, 14:51:49 UTC · 7.084°N, 123.449°E
A magnitude 5.6 earthquake struck 39 km SSE of Panubigan, Philippines on Friday, October 22, 1976, 14:51:49 UTC, at a depth of 33.0 km (shallow). It is the strongest earthquake within 300 km since an M6.0 on September 29, 1976.
- Magnitude
- 5.6
- Moderate · mb
- Depth
- 33 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- IV
- Light (ShakeMap)
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeDashed circle: 75 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)
In context
How big was it, and why here?
Energy released
4 kilotons of TNT
That is about 1/4 of the Hiroshima bomb. It released about 8 times the energy of a magnitude 5.0.
Tectonic setting
418 km
from the nearest mapped plate boundary, between the Philippine Sea and Sunda 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 3 M2.5+ earthquakes within 75 km in the following 30 days; the largest was M5.9 on November 7, 1976. 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 149 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.31918 Mindanao, Philippines EarthquakeAugust 15, 1918 · 182 km S of this epicenter
- 7.919 km WNW of Palimbang, PhilippinesAugust 16, 1976 · 111 km SE of this epicenter
- 7.410 km ESE of Basak, PhilippinesDecember 19, 1928 · 97 km SE of this epicenter
- 7.4Mindanao, PhilippinesMarch 31, 1955 · 71 km NW of this epicenter
- 7.312 km SSW of Kipit, PhilippinesOctober 20, 1942 · 145 km NW of this epicenter
- 7.25 km NW of Kadingilan, PhilippinesMarch 2, 1923 · 169 km E of this epicenter
- 7.019 km W of Sigaboy, PhilippinesNovember 16, 1927 · 274 km E of this epicenter
- 6.937 km S of Daliao, PhilippinesJanuary 31, 1917 · 237 km SE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 24 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 8,655 recorded deaths. The most severe:
- 1976M8.0
Mindanao: S
16 Aug 1976 · 113 km away · intensity VI
8,000 deaths$134 million damagetsunami
- 1955M7.4
Mindanao: Lanao,Ozamiz,Cotabato
31 Mar 1955 · 71 km away · intensity VIII
465 deaths$5 million damagetsunami
- 1928M7.4
Cotabato,N Coast Of Illana Bay
19 Dec 1928 · 97 km away · intensity VII
97 deathsModerate damage ($1–5M)tsunami
- 1918M8.3
Mindanao: Cotabato
15 Aug 1918 · 182 km away · intensity X
52 deathsSevere damage ($5–24M)tsunami
- 1925M6.8
W. Luzon Island, Philippines
5 May 1925 · 260 km away · intensity IX
17 deathsModerate damage ($1–5M)tsunami
- 1897M8.7
Mindanao, Zamboanga, Sulu, Isabela
21 Sep 1897 · 200 km away · intensity IX
13 deathsSevere damage ($5–24M)tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.