Seismic Data
The quake's epicentre was located near the town of Los Amates, in the eastern part of the Motagua Fault, a left-lateral strike-slip fault that forms the tectonic boundary between the North American plate and the Caribbean plate. Ground shaking was felt during approximately 39 seconds, and caused visible rupturing over 230 km along the Motagua fault, while the inferred length of faulting—based on aftershock registration—was estimated at 300 km. Average horizontal displacement along the Motagua fault was 100 cm, with a maximum displacement of 326 cm.
Maximum seismic intensity (MM IX) was located in the Mixco area, some sections of Guatemala City and in Gualán. A seismic intensity of MM VI covered an area of 33,000 km². Liquefaction and sand boils were observed in several locations with high seismic intensity.
The main quake activated secondary fault zones, including the Mixco fault, located in a densely populated area just north-west of Guatemala City.
Several heavy aftershocks, ranging from 5.2 to 5.8 Mw caused additional casualties and hampered relief efforts.
| Date | Origin Time | Coordinates | Location | Depth | Magnitude |
| Feb. 04 1976 | 09.30.28.3 | 14°42′N 90°36′W / 14.7°N 90.6°W / 14.7; -90.6 | 7 km NNE of Mixco | 5 km | 5.8 Mw |
| Feb. 06 1976 | 04.11.03.3 | 14°36′N 91°06′W / 14.6°N 91.1°W / 14.6; -91.1 | 6 km SSE of San Lucas Tolimán | 5 km | 4.8 Mw |
| Feb. 06 1976 | 18.11.59.2 | 14°18′N 90°12′W / 14.3°N 90.2°W / 14.3; -90.2 | 11 km ENE of Cuilapa | 5 km | 5.2 Mw |
| Feb. 06 1976 | 18.19.17.7 | 14°42′N 90°36′W / 14.7°N 90.6°W / 14.7; -90.6 | 5 km ENE of San Pedro Sacatepéquez | 5 km | 5.8 Mw |
| Feb. 08 1976 | 08.13.51.9 | 15°42′N 88°30′W / 15.7°N 88.5°W / 15.7; -88.5 | 13 km SE of Puerto Barrios | 5 km | 5.7 Mw |
| Feb. 09 1976 | 11.44.46.7 | 15°18′N 89°06′W / 15.3°N 89.1°W / 15.3; -89.1 | 30 km WSW of Morales | 5 km | 5.1 Mw |
| Feb. 10 1976 | 06.17.43.0 | 15°00′N 89°42′W / 15.0°N 89.7°W / 15.0; -89.7 | 18 km WNW of Zacapa | 5 km | 4.7 Mw |
| Mar. 07 1976 | 02.54.05.4 | 14°54′N 90°54′W / 14.9°N 90.9°W / 14.9; -90.9 | 14.5 km SW of Joyabaj | 5 km | 4.8 Mw |
| Mar. 07 1976 | 03.15.40.3 | 14°42′N 90°30′W / 14.7°N 90.5°W / 14.7; -90.5 | Chinautla (9 km North of Guatemala City) | 5 km | 4.9 Mw |
Read more about this topic: 1976 Guatemala Earthquake
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