1966 Toro earthquake

Tectonic setting

The earthquake occurred in the Mt Rwenzori region, which lies within the Western Rift Valley of the East Africa Rift System, between Lake Edward and Lake Albert. The Mt. Ruwenzori region is the most seismically active region in Uganda and also one of the most seismically active zones in the East Africa Rift System and is bounded by steep active normal faults. The calculated focal mechanism for the earthquake was normal faulting in type, although the focal mechanisms of three of the aftershocks were dominantly strike-slip in type.

Damage

Extensive damage was reported in both Uganda and the DRC. The earthquake caused 157 deaths: 104 in Uganda, one in Tanzania and 52 in the DRC. Buildings collapsed in both Uganda and the DRC. In Bundibugyo, the Court Hall was damaged. Cracks and fissures were observed on the ground. This earthquake could be felt in Uganda, the Democratic Republic of the Congo, Rwanda, Burundi, Tanzania, and Kenya. Landslides triggered by the earthquake blocked roads, impeding relief efforts.

According to press reports, a strong aftershock on May 18, 1966, caused 90 deaths in the DRC. This aftershock caused damage to buildings in both Uganda and the DRC.

Earthquake

The earthquake was associated with 20 km of surface faulting showing a downthrow of about 1.8 m to the southeast, consistent with one of the two possible fault planes from the focal mechanism.

The earthquake was preceded by numerous foreshocks on March 18 and 19, 1966, and was followed by many aftershocks during the next two months, nine of them with a magnitude of 5.0 or greater.

The energy release of the main shock was about 2×1017 Nm. The energy release associated with aftershocks after April 18 was also significant. The sum of energy release of the aftershocks up to 45 days after the main shock was also about 2×1017 Nm, i.e. roughly equal to that of the main shock.

References

References

1. Loupekine, I.S.. (July 1966). "Earthquake reconnaissance mission: Uganda the Toro earthquake of 20 March 1966". UNESCO.
2. Mavonga, T.. (2009). "Seismic hazard in the DRC and Western Rift Valley of Africa".
3. "The seismicity and tectonics of Uganda" by N. Maasha
4. Twesigomwe, E.M.. (1997). "Seismic hazards in Uganda". Journal of African Earth Sciences.
5. Foster, A.N.. (1998). "Source parameters of large African earthquakes:implications for crustal rheology and regional kinematics". [[Geophysical Journal International]].
6. Zana, N.. (1981). "Focal Mechanism of Major Earthquakes in the Western Rift Valley of Africa". Tohoku Geophysical Journal.
7. National Geophysical Data Center. "Significant earthquake".
8. Engdahl, E. R.. (2002). "International Handbook of Earthquake & Engineering Seismology". [[Academic Press]].