Reviewed by USGSMexico41y ago
M3.6 earthquake 95 km SW of Ixtapa, Mexico
Friday, October 4, 1985, 07:20:14 UTC · 16.995°N, 102.197°W
A magnitude 3.6 earthquake struck 95 km SW of Ixtapa, Mexico on Friday, October 4, 1985, 07:20:14 UTC, at a depth of 33.0 km (shallow).
- Magnitude
- 3.6
- Minor · mb
- Depth
- 33 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
4 tons of TNT
That is about 1/3,975 of the Hiroshima bomb. A magnitude 5.0 releases about 126 times more energy.
Tectonic setting
21 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
33 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:
- 8.01985 Michoacan, Mexico EarthquakeSeptember 19, 1985 · 138 km N of this epicenter
- 7.87 km E of Los Tepames, MexicoJune 18, 1932 · 273 km NW of this epicenter
- 7.621 km ESE of Coalcomán de Vázquez Pallares, MexicoApril 15, 1941 · 205 km NW of this epicenter
- 7.619 km W of Arteaga, MexicoJune 7, 1911 · 155 km N of this epicenter
- 7.612 km SSE of Vallecitos de Zaragoza, MexicoMarch 14, 1979 · 134 km NE of this epicenter
- 7.67 km N of Pantla, MexicoSeptember 21, 1985 · 107 km NE of this epicenter
- 7.525 km S of Tetitlán, MexicoDecember 16, 1911 · 163 km E of this epicenter
- 7.527 km SSE of San Andrés Playa Encantada (El Podrido), MexicoJuly 30, 1909 · 290 km E of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 41 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 13,770 recorded deaths. The most severe:
- 1985M8.1
Michoacan: Mexico City
19 Sep 1985 · 138 km away · intensity IX
9,500 deaths$4.0 billion damagetsunami
- 1806M7.5
Jalisco,Oaxaca,Michoacan
25 Mar 1806 · 271 km away · intensity VIII
2,000 deathsExtreme damage ($25M+)
- 1818M8.2
Morelos-Guerrero,Mexico City,Guadalajara
31 May 1818 · 298 km away · intensity X
2,000 deathsSevere damage ($5–24M)tsunami
- 1941M7.6
Michoacan, Colima, Jalisco
15 Apr 1941 · 205 km away · intensity VII
84 deaths$2 million damagetsunami
- 1964M7.3
Guerrero
6 Jul 1964 · 211 km away
78 deathsSevere damage ($5–24M)
- 1973M7.5
S, Farias, Tecoman
30 Jan 1973 · 186 km away
56 deathsModerate damage ($1–5M)tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.