Reviewed by USGSMexico57y ago
M6.6 earthquake 86 km WSW of Aquiles Serdán, Mexico
Thursday, April 30, 1970, 08:33:01 UTC · 14.569°N, 93.225°W
A magnitude 6.6 earthquake struck 86 km WSW of Aquiles Serdán, Mexico on Thursday, April 30, 1970, 08:33:01 UTC, at a depth of 26.4 km (shallow). It is the strongest earthquake within 300 km since an M7.3 on April 29, 1970.
- Magnitude
- 6.6
- Strong · mw
- Depth
- 26 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- V
- Moderate (ShakeMap)
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeDashed circle: 100 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)
In context
How big was it, and why here?
Energy released
133 kilotons of TNT
That is about 9 times the Hiroshima bomb. It released about 279 times the energy of a magnitude 5.0.
Tectonic setting
77 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
26 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 100 km
USGS lists 6 M2.5+ earthquakes within 100 km in the following 30 days; the largest was M6.0 on April 30, 1970. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
- 5.764 km SW of Puerto Madero, Mexico57y ago · 58 km SE of this epicenter
- 5.897 km SSW of La Esperanza (El Zapotal), Mexico57y ago · 48 km W of this epicenter
- 5.898 km SSW of La Esperanza (El Zapotal), Mexico57y ago · 43 km W of this epicenter
- 5.8101 km WSW of Puerto Madero, Mexico57y ago · 21 km SW of this epicenter
- 5.992 km SSW of La Esperanza (El Zapotal), Mexico57y ago · 17 km NW of this epicenter
- 6.0121 km WSW of Puerto Madero, Mexico57y ago · 41 km SW of this epicenter
Regional history
Past M5+ earthquakes within 300 km
USGS lists 120 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.726 km SSW of La Gomera, GuatemalaAugust 6, 1942 · 236 km E of this epicenter
- 7.34 km SSW of Puerto Madero, MexicoDecember 14, 1935 · 86 km E of this epicenter
- 7.334 km SW of Puerto Madero, MexicoApril 29, 1970 · 67 km E of this epicenter
- 7.2127 km SW of La Esperanza (El Zapotal), MexicoMarch 30, 1914 · 81 km W of this epicenter
- 7.21 km NNW of Champerico, GuatemalaOctober 23, 1950 · 144 km E of this epicenter
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 · 283 km away · intensity IX
2,650 deathsExtreme damage ($25M+)
- 1902M7.5
Quezaltenango, San Marcos
19 Apr 1902 · 248 km away
2,000 deathsSevere damage ($5–24M)tsunami
- 1773
St. Jago
3 Jun 1773 · 272 km away
600 deathsExtreme damage ($25M+)tsunami
- 1874M7.1
Antigua,Chimaltenango,Amatitlan
3 Sep 1874 · 272 km away · intensity VIII
300 deathsSevere damage ($5–24M)
- 1773M7.5
Antigua
29 Jul 1773 · 272 km away · intensity VIII
100 deathsModerate damage ($1–5M)
- 1816M7.5
Soloma
22 Jul 1816 · 212 km away · intensity IX
23 deathsSevere damage ($5–24M)
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.