1973 Colima earthquake

On January 30, at 15:01 (), a magnitude 7.6 earthquake struck 43 km beneath the Sierra Madre del Sur range in the Mexican states of Colima, Jalisco and Michoacán. On the Mercalli intensity scale, the earthquake reached a maximum intensity of X ("Extreme"), causing serious damage in the region. At least 56 people were killed and about 390 were injured. The event is commonly referred to as the Colima earthquake.
Tectonic setting.
Off the west coast of Mexico is the Middle America Trench; a convergent plate boundary where the Cocos and Rivera plates subducts beneath the North American Plate at a rate of ~6-9 cm/yr. The interface of this plate boundary is a huge thrust fault fault known as a megathrust which occasionally produces large megathrust earthquakes and tsunamis.
Earthquake.
The January 30 earthquake ruptured a shallow-angle section of the megathrust near a triple junction with the Rivera Plate. Its location places it very close to the rupture patch from the 1941 earthquake. The depth of the event varies between authors, from as shallow as 8 km to 35 km, while the USGS-ANSS event page places it at 43 km. It is estimated that a 145 km by 85 km section of the subduction zone was involved in the rupture which propagated at a velocity of 2.7 km/s. Rupture occurred the subduction interface at between 5 km and 27 km depth. Prior to the earthquake, that section of the subduction zone was designated a seismic gap which has not experience any earthquakes in recent memory. The Mexico City earthquake rupture would overlap that of the 1973 quake 12 years later.
Effects.
The earthquake was powerful enough to be felt across the country to the Gulf of Mexico. Severe shaking and heavy damages were limited to Colima, Jalisco and Michoacán. Fifty six people died and 390 were injured by this event. Tecomán and Coahuayana suffered significant damages from the violent ground motions. Landslides and ground fissures were discovered along the relatively unpopulated coasts of Michoacán. Water, electricity and telephone lives were cut throughout.
In Mexico City, the earthquake was felt strongly in the north and western part of the city for at least 40 seconds. It caused mass hysteria and light damages to high-rise buildings.
Tsunami.
A moderate tsunami with amplitudes of 0.40 to 1.16 meters was observed along the Mexican coast. Tidal gauges in Hawaii also recorded the tsunami at 0.21 meter.