M7.5 earthquake 45 km SW of Sarangani, Philippines

Tuesday, November 20, 1984, 08:15:16 UTC · 5.167°N, 125.124°E

A magnitude 7.5 earthquake struck 45 km SW of Sarangani, Philippines on Tuesday, November 20, 1984, 08:15:16 UTC, at a depth of 202.2 km (intermediate). It is the strongest earthquake within 300 km since an M7.9 on August 16, 1976.

Magnitude: 7.5; Major · mw
Depth: 202 km; Intermediate
Felt reports: 0; Did You Feel It?
Est. shaking: VI; Strong (ShakeMap)
PAGER alert: None; Not issued
Tsunami: No flag; USGS feed

Outlined circle: this earthquakeDashed circle: 200 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

2.7 megatons of TNT

That is about 178 times the Hiroshima bomb. It released about 5,623 times the energy of a magnitude 5.0.

Tectonic setting

266 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

202 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 200 km

USGS lists 13 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M5.4 on December 8, 1984. 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 630 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 11,104 recorded deaths. The most severe:

1976M8.0
Mindanao: S
16 Aug 1976 · 170 km away · intensity VI
8,000 deaths$134 million damagetsunami
1856
Sangihe Pulau (Volcanic)
2 Mar 1856 · 172 km away
2,806 deathsSevere damage ($5–24M)tsunami
1913M7.8
Sangihe Island
14 Mar 1913 · 112 km away · intensity IX
138 deathsModerate damage ($1–5M)tsunami
1928M7.4
Cotabato,N Coast Of Illana Bay
19 Dec 1928 · 197 km away · intensity VII
97 deathsModerate damage ($1–5M)tsunami
1918M8.3
Mindanao: Cotabato
15 Aug 1918 · 132 km away · intensity X
52 deathsSevere damage ($5–24M)tsunami
1917M6.4
S Mindanao: Glan,Glan Padidu,Tuyan
31 Jan 1917 · 94 km away · intensity IX
7 deathsModerate damage ($1–5M)tsunami

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

Nearby trackers