M8.3 earthquake 1918 Mindanao, Philippines Earthquake

Thursday, August 15, 1918, 12:18:24 UTC · 5.538°N, 123.994°E

A magnitude 8.3 earthquake struck 1918 Mindanao, Philippines Earthquake on Thursday, August 15, 1918, 12:18:24 UTC, at a depth of 20.0 km (shallow). No earthquake of this size or larger appears within 300 km in the USGS catalog since 1900.

Magnitude: 8.3; Great · mw
Depth: 20 km; Shallow
Felt reports: 0; Did You Feel It?
Est. shaking: VII; Very strong (ShakeMap)
PAGER alert: None; Not issued
Tsunami: No flag; USGS feed

Outlined circle: this earthquakeDashed circle: 400 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

43 megatons of TNT

That is about 2,823 times the Hiroshima bomb. It released about 89,125 times the energy of a magnitude 5.0.

Tectonic setting

375 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

20 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 400 km

USGS lists 6 M2.5+ earthquakes within 400 km in the following 30 days; the largest was M6.7 on August 15, 1918. 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 9 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 16 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 3,020 recorded deaths. The most severe:

1856
Sangihe Pulau (Volcanic)
2 Mar 1856 · 266 km away
2,806 deathsSevere damage ($5–24M)tsunami
1913M7.8
Sangihe Island
14 Mar 1913 · 236 km away · intensity IX
138 deathsModerate damage ($1–5M)tsunami
1918M8.3
Mindanao: Cotabato
15 Aug 1918 · 0 km away · intensity X
52 deathsSevere damage ($5–24M)tsunami
1897M8.7
Mindanao, Zamboanga, Sulu, Isabela
21 Sep 1897 · 227 km away · intensity IX
13 deathsSevere damage ($5–24M)tsunami
1917M6.4
S Mindanao: Glan,Glan Padidu,Tuyan
31 Jan 1917 · 123 km away · intensity IX
7 deathsModerate damage ($1–5M)tsunami
1870
Mindanao: Davao,Blanco
4 Nov 1870 · 225 km away
4 deathsModerate damage ($1–5M)

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

Nearby trackers