Reviewed by USGSMexico48y ago
M4.9 earthquake 2 km WSW of Petatlán, Mexico
Tuesday, March 20, 1979, 00:27:55 UTC · 17.532°N, 101.293°W
A magnitude 4.9 earthquake struck 2 km WSW of Petatlán, Mexico on Tuesday, March 20, 1979, 00:27:55 UTC, at a depth of 51.0 km (shallow). It is the strongest earthquake within 300 km since an M5.4 on March 18, 1979.
- Magnitude
- 4.9
- Light · mb
- Depth
- 51 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
338 tons of TNT
That is about 1/45 of the Hiroshima bomb. A magnitude 5.0 releases about 1 times more energy.
Tectonic setting
69 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
51 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 119 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.87 km E of Los Tepames, MexicoJune 18, 1932 · 294 km NW of this epicenter
- 7.621 km ESE of Coalcomán de Vázquez Pallares, MexicoApril 15, 1941 · 220 km NW of this epicenter
- 7.68 km ENE of Apantla, MexicoJuly 28, 1957 · 240 km E of this epicenter
- 7.619 km W of Arteaga, MexicoJune 7, 1911 · 155 km NW of this epicenter
- 7.612 km SSE of Vallecitos de Zaragoza, MexicoMarch 14, 1979 · 31 km N of this epicenter
- 7.525 km S of Tetitlán, MexicoDecember 16, 1911 · 94 km SE of this epicenter
- 7.527 km SSE of San Andrés Playa Encantada (El Podrido), MexicoJuly 30, 1909 · 222 km SE of this epicenter
- 7.535 km SW of Aguililla, MexicoJanuary 30, 1973 · 209 km NW of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 49 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 534 recorded deaths. The most severe:
- 1912M6.7
Central, Acambay, Tixmadeje
19 Nov 1912 · 270 km away
202 deathsSevere damage ($5–24M)
- 1941M7.6
Michoacan, Colima, Jalisco
15 Apr 1941 · 220 km away · intensity VII
84 deaths$2 million damagetsunami
- 1964M7.3
Guerrero
6 Jul 1964 · 99 km away
78 deathsSevere damage ($5–24M)
- 1957M7.9
Acapulco,Mexico City
28 Jul 1957 · 260 km away · intensity VII
65 deaths$25 million damagetsunami
- 1973M7.5
S, Farias, Tecoman
30 Jan 1973 · 209 km away
56 deathsModerate damage ($1–5M)tsunami
- 1864M7.0
Puebla,Veracruz,Acultzingo,Acatzingo
3 Oct 1864 · 127 km away
20 deathsSevere damage ($5–24M)
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.