M7.3 earthquake 34 km SW of Puerto Madero, Mexico

Wednesday, April 29, 1970, 14:01:35 UTC · 14.472°N, 92.612°W

A magnitude 7.3 earthquake struck 34 km SW of Puerto Madero, Mexico on Wednesday, April 29, 1970, 14:01:35 UTC, at a depth of 35.0 km (shallow). It is the strongest earthquake within 300 km since an M7.7 on August 6, 1942.

Magnitude: 7.3; Major · mw
Depth: 35 km; Shallow
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

1.3 megatons of TNT

That is about 89 times the Hiroshima bomb. It released about 2,818 times the energy of a magnitude 5.0.

Tectonic setting

91 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

35 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 200 km

USGS lists 9 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M6.6 on April 30, 1970. 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 128 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 20 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 5,693 recorded deaths. The most severe:

1917M6.0
Guatemala City
26 Dec 1917 · 217 km away · intensity IX
2,650 deathsExtreme damage ($25M+)
1902M7.5
Quezaltenango, San Marcos
19 Apr 1902 · 181 km away
2,000 deathsSevere damage ($5–24M)tsunami
1773
St. Jago
3 Jun 1773 · 206 km away
600 deathsExtreme damage ($25M+)tsunami
1874M7.1
Antigua,Chimaltenango,Amatitlan
3 Sep 1874 · 206 km away · intensity VIII
300 deathsSevere damage ($5–24M)
1773M7.5
Antigua
29 Jul 1773 · 206 km away · intensity VIII
100 deathsModerate damage ($1–5M)
1816M7.5
Soloma
22 Jul 1816 · 165 km away · intensity IX
23 deathsSevere damage ($5–24M)

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

Nearby trackers