M5.5 earthquake 139 km SE of Pondaguitan, Philippines

Friday, December 8, 1972, 20:17:13 UTC · 5.590°N, 127.171°E

A magnitude 5.5 earthquake struck 139 km SE of Pondaguitan, Philippines on Friday, December 8, 1972, 20:17:13 UTC, at a depth of 45.7 km (shallow). It is the strongest earthquake within 300 km since an M5.6 on December 8, 1972.

Magnitude: 5.5; Moderate · mw
Depth: 46 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: 75 km aftershock search area

In context

How big was it, and why here?

Energy released

3 kilotons of TNT

That is about 1/6 of the Hiroshima bomb. It released about 6 times the energy of a magnitude 5.0.

Tectonic setting

35 km

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

Depth: shallow

46 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 7 M2.5+ earthquakes within 75 km in the following 30 days; the largest was M5.9 on December 28, 1972. 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 213 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 22 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 2,955 recorded deaths. The most severe:

1856
Sangihe Pulau (Volcanic)
2 Mar 1856 · 283 km away
2,806 deathsSevere damage ($5–24M)tsunami
1913M7.8
Sangihe Island
14 Mar 1913 · 119 km away · intensity IX
138 deathsModerate damage ($1–5M)tsunami
1917M6.4
S Mindanao: Glan,Glan Padidu,Tuyan
31 Jan 1917 · 244 km away · intensity IX
7 deathsModerate damage ($1–5M)tsunami
1870
Mindanao: Davao,Blanco
4 Nov 1870 · 251 km away
4 deathsModerate damage ($1–5M)
1924M8.3
E Mindanao: Mati,Suriga
14 Apr 1924 · 125 km away · intensity IX
Severe damage ($5–24M)tsunami
1903M7.8
Davao Gulf
28 Dec 1903 · 203 km away · intensity VIII
Moderate damage ($1–5M)

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

Nearby trackers