Reviewed by USGSMexico41y ago
M3.6 earthquake 18 km WSW of Ixtapa, Mexico
Saturday, October 5, 1985, 06:55:09 UTC · 17.606°N, 101.802°W
A magnitude 3.6 earthquake struck 18 km WSW of Ixtapa, Mexico on Saturday, October 5, 1985, 06:55:09 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 earthquakeDashed circle: 50 km aftershock search area
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
56 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 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 132 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 · 101 km NW of this epicenter
- 7.87 km E of Los Tepames, MexicoJune 18, 1932 · 247 km NW of this epicenter
- 7.621 km ESE of Coalcomán de Vázquez Pallares, MexicoApril 15, 1941 · 173 km NW of this epicenter
- 7.68 km ENE of Apantla, MexicoJuly 28, 1957 · 294 km E of this epicenter
- 7.619 km W of Arteaga, MexicoJune 7, 1911 · 110 km NW of this epicenter
- 7.612 km SSE of Vallecitos de Zaragoza, MexicoMarch 14, 1979 · 60 km NE of this epicenter
- 7.67 km N of Pantla, MexicoSeptember 21, 1985 · 27 km NE of this epicenter
- 7.525 km S of Tetitlán, MexicoDecember 16, 1911 · 142 km SE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 54 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 13,972 recorded deaths. The most severe:
- 1985M8.1
Michoacan: Mexico City
19 Sep 1985 · 101 km away · intensity IX
9,500 deaths$4.0 billion damagetsunami
- 1806M7.5
Jalisco,Oaxaca,Michoacan
25 Mar 1806 · 255 km away · intensity VIII
2,000 deathsExtreme damage ($25M+)
- 1818M8.2
Morelos-Guerrero,Mexico City,Guadalajara
31 May 1818 · 280 km away · intensity X
2,000 deathsSevere damage ($5–24M)tsunami
- 1912M6.7
Central, Acambay, Tixmadeje
19 Nov 1912 · 297 km away
202 deathsSevere damage ($5–24M)
- 1941M7.6
Michoacan, Colima, Jalisco
15 Apr 1941 · 173 km away · intensity VII
84 deaths$2 million damagetsunami
- 1964M7.3
Guerrero
6 Jul 1964 · 140 km away
78 deathsSevere damage ($5–24M)
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.