M6.0 earthquake 128 km E of Pondaguitan, Philippines

Friday, March 9, 1973, 10:06:37 UTC · 6.274°N, 127.336°E

A magnitude 6.0 earthquake struck 128 km E of Pondaguitan, Philippines on Friday, March 9, 1973, 10:06:37 UTC, at a depth of 55.0 km (shallow). It is the strongest earthquake within 300 km since an M6.0 on December 2, 1972.

Magnitude: 6.0; Strong · mb
Depth: 55 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: 100 km aftershock search area

In context

How big was it, and why here?

Energy released

15 kilotons of TNT

That is about the energy of the Hiroshima bomb. It released about 32 times the energy of a magnitude 5.0.

Tectonic setting

2 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

55 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 6 M2.5+ earthquakes within 100 km in the following 30 days; the largest was M4.9 on March 31, 1973. 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 242 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 24 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 149 recorded deaths. The most severe:

1913M7.8
Sangihe Island
14 Mar 1913 · 169 km away · intensity IX
138 deathsModerate damage ($1–5M)tsunami
1917M6.4
S Mindanao: Glan,Glan Padidu,Tuyan
31 Jan 1917 · 260 km away · intensity IX
7 deathsModerate damage ($1–5M)tsunami
1870
Mindanao: Davao,Blanco
4 Nov 1870 · 229 km away
4 deathsModerate damage ($1–5M)
1924M8.3
E Mindanao: Mati,Suriga
14 Apr 1924 · 96 km away · intensity IX
Severe damage ($5–24M)tsunami
1903M7.8
Davao Gulf
28 Dec 1903 · 168 km away · intensity VIII
Moderate damage ($1–5M)
1936M7.7
Talaud Islands
1 Apr 1936 · 218 km away · intensity IX
Moderate damage ($1–5M)tsunami

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

Nearby trackers