Reviewed by USGSPhilippines54y ago
M5.1 earthquake 48 km SSE of Pondaguitan, Philippines
Thursday, March 22, 1973, 22:39:15 UTC · 5.947°N, 126.318°E
A magnitude 5.1 earthquake struck 48 km SSE of Pondaguitan, Philippines on Thursday, March 22, 1973, 22:39:15 UTC, at a depth of 102.0 km (intermediate). It is the strongest earthquake within 300 km since an M5.5 on March 12, 1973.
- Magnitude
- 5.1
- Moderate · mb
- Depth
- 102 km
- Intermediate
- 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
674 tons of TNT
That is about 1/22 of the Hiroshima bomb. It released about 1 times the energy of a magnitude 5.0.
Tectonic setting
116 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: intermediate
102 km
Intermediate-depth earthquakes usually break inside a plate that is sinking into the mantle. Shaking spreads over a wide area but is gentler at the epicenter than a shallow quake of the same size.
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 4 M2.5+ earthquakes within 75 km in the following 30 days; the largest was M5.3 on April 13, 1973. 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 250 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 · 261 km W of this epicenter
- 8.11924 Mindanao, Philippines EarthquakeApril 14, 1924 · 77 km N of this epicenter
- 8.01972 Mindanao, Philippines EarthquakeDecember 2, 1972 · 66 km NE of this epicenter
- 7.947 km ESE of Kalbay, PhilippinesMarch 14, 1913 · 65 km SW of this epicenter
- 7.877 km E of Baculin, PhilippinesMay 25, 1943 · 190 km NE of this epicenter
- 7.8161 km SE of Sarangani, PhilippinesApril 1, 1936 · 187 km S of this epicenter
- 7.774 km ENE of Barcelona, PhilippinesJuly 12, 1911 · 293 km N of this epicenter
- 7.6101 km SE of Sarangani, PhilippinesDecember 16, 1910 · 146 km S of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 29 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 3,104 recorded deaths. The most severe:
- 1856
Sangihe Pulau (Volcanic)
2 Mar 1856 · 269 km away
2,806 deathsSevere damage ($5–24M)tsunami
- 1913M7.8
Sangihe Island
14 Mar 1913 · 69 km away · intensity IX
138 deathsModerate damage ($1–5M)tsunami
- 1928M7.4
Cotabato,N Coast Of Illana Bay
19 Dec 1928 · 244 km away · intensity VII
97 deathsModerate damage ($1–5M)tsunami
- 1918M8.3
Mindanao: Cotabato
15 Aug 1918 · 261 km away · intensity X
52 deathsSevere damage ($5–24M)tsunami
- 1917M6.4
S Mindanao: Glan,Glan Padidu,Tuyan
31 Jan 1917 · 146 km away · intensity IX
7 deathsModerate damage ($1–5M)tsunami
- 1870
Mindanao: Davao,Blanco
4 Nov 1870 · 155 km away
4 deathsModerate damage ($1–5M)
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.