Reviewed by USGSMexico41y ago
M4.0 earthquake 6 km SSW of Los Achotes, Mexico
Sunday, October 6, 1985, 06:28:40 UTC · 17.546°N, 101.438°W
A magnitude 4.0 earthquake struck 6 km SSW of Los Achotes, Mexico on Sunday, October 6, 1985, 06:28:40 UTC, at a depth of 46.3 km (shallow).
- Magnitude
- 4.0
- Light · mb
- 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: 50 km aftershock search area
In context
How big was it, and why here?
Energy released
15 tons of TNT
That is about 1/998 of the Hiroshima bomb. A magnitude 5.0 releases about 32 times more energy.
Tectonic setting
63 km
from the nearest mapped plate boundary, between the Cocos and North American 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 50 km
USGS lists 3 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M4.2 on November 3, 1985. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 138 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.01985 Michoacan, Mexico EarthquakeSeptember 19, 1985 · 136 km NW of this epicenter
- 7.87 km E of Los Tepames, MexicoJune 18, 1932 · 281 km NW of this epicenter
- 7.621 km ESE of Coalcomán de Vázquez Pallares, MexicoApril 15, 1941 · 207 km NW of this epicenter
- 7.68 km ENE of Apantla, MexicoJuly 28, 1957 · 255 km E of this epicenter
- 7.619 km W of Arteaga, MexicoJune 7, 1911 · 142 km NW of this epicenter
- 7.612 km SSE of Vallecitos de Zaragoza, MexicoMarch 14, 1979 · 34 km NE of this epicenter
- 7.67 km N of Pantla, MexicoSeptember 21, 1985 · 36 km NW of this epicenter
- 7.525 km S of Tetitlán, MexicoDecember 16, 1911 · 107 km SE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 52 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 12,037 recorded deaths. The most severe:
- 1985M8.1
Michoacan: Mexico City
19 Sep 1985 · 136 km away · intensity IX
9,500 deaths$4.0 billion damagetsunami
- 1806M7.5
Jalisco,Oaxaca,Michoacan
25 Mar 1806 · 291 km away · intensity VIII
2,000 deathsExtreme damage ($25M+)
- 1912M6.7
Central, Acambay, Tixmadeje
19 Nov 1912 · 278 km away
202 deathsSevere damage ($5–24M)
- 1941M7.6
Michoacan, Colima, Jalisco
15 Apr 1941 · 207 km away · intensity VII
84 deaths$2 million damagetsunami
- 1964M7.3
Guerrero
6 Jul 1964 · 110 km away
78 deathsSevere damage ($5–24M)
- 1957M7.9
Acapulco,Mexico City
28 Jul 1957 · 274 km away · intensity VII
65 deaths$25 million damagetsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.