Reviewed by USGSMexico41y ago
M3.9 earthquake 9 km NE of Coajomulco, Mexico
Saturday, October 19, 1985, 08:28:36 UTC · 19.083°N, 99.127°W
A magnitude 3.9 earthquake struck 9 km NE of Coajomulco, Mexico on Saturday, October 19, 1985, 08:28:36 UTC, at a depth of 10.0 km (shallow).
- Magnitude
- 3.9
- Minor · mb
- Depth
- 10 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 earthquake
In context
How big was it, and why here?
Energy released
11 tons of TNT
That is about 1/1,410 of the Hiroshima bomb. A magnitude 5.0 releases about 45 times more energy.
Tectonic setting
316 km
from the nearest mapped plate boundary, between the Cocos and North American plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.
Depth: shallow
10 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 50 km
USGS has not published any M2.5+ earthquake within 50 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 123 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.68 km ENE of Apantla, MexicoJuly 28, 1957 · 226 km S of this epicenter
- 7.612 km SSE of Vallecitos de Zaragoza, MexicoMarch 14, 1979 · 267 km SW of this epicenter
- 7.525 km S of Tetitlán, MexicoDecember 16, 1911 · 289 km SW of this epicenter
- 7.527 km SSE of San Andrés Playa Encantada (El Podrido), MexicoJuly 30, 1909 · 294 km S of this epicenter
- 7.56 km S of Copala, MexicoMarch 26, 1908 · 282 km S of this epicenter
- 7.43 km W of Huixtepec, MexicoDecember 23, 1937 · 282 km S of this epicenter
- 7.310 km SW of Villa Nicolás Bravo, MexicoJuly 6, 1964 · 188 km SW of this epicenter
- 7.215 km SSW of Colonia Luces en el Mar, MexicoMarch 27, 1908 · 273 km S of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 56 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 1,895 recorded deaths. The most severe:
- 1920M7.8
Veracruz: Cozautlan, Puebla: Patlanala
3 Jan 1920 · 227 km away · intensity X
648 deathsModerate damage ($1–5M)
- 1973M6.2
Veracruz, Mexico City
28 Aug 1973 · 281 km away · intensity VII
527 deathsSevere damage ($5–24M)
- 1980M6.4
S, Huajapan De Leon, Oaxaca
24 Oct 1980 · 135 km away · intensity IX
300 deaths$5 million damage
- 1912M6.7
Central, Acambay, Tixmadeje
19 Nov 1912 · 96 km away
202 deathsSevere damage ($5–24M)
- 1964M7.3
Guerrero
6 Jul 1964 · 188 km away
78 deathsSevere damage ($5–24M)
- 1957M7.9
Acapulco,Mexico City
28 Jul 1957 · 287 km away · intensity VII
65 deaths$25 million damagetsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.