2023 Guayas earthquake

2023 Guayas earthquake

2023 Guayas earthquake is located in Ecuador
Magnitude	6.8 ṃ
Depth	65.8 km (40.9 mi)
Epicenter
Type	Oblique-slip
Areas affected	Ecuador and Peru
Max. intensity	VII (Very strong)
Casualties	17 dead, ≥381 injured

A very strong earthquake struck Guayas Province, Ecuador on 18 March 2023. It measured 6.8 on the moment magnitude scale, and struck with a hypocenter 65.8 km (40.9 mi) deep. It caused major damage and 16 fatalities in southwestern Ecuador, while an additional fatality and dozens of injuries were reported in Peru.

Tectonic setting

The active tectonics of Ecuador is dominated by the effects of the subduction of the Nazca Plate beneath the South American Plate. Ecuador lies within the Northern Volcanic Zone where the subduction zone is moving at a rate of 7 cm/yr to the east-northeast, significantly oblique to the trend of this segment of the Andes. The subduction zone has an overall dip of 25–30°, but varies rapidly along strike due to the effects of subduction of the Carnegie Ridge. The Carnegie Ridge is an oceanic plateau that formed as the Nazca Plate passed over the Galapagos hotspot. The plate interface above the subducted part of the ridge has a shallower dip than the area to both north and south, the boundaries interpreted to consist of two large tears in the downgoing Nazca Plate. The northern part of Ecuador overlies the subducted part of the Carnegie Ridge and is an area where the Nazca Plate is interpreted to be strongly coupled to the South American Plate, causing an unusually large degree of intraplate deformation. The main active fault zones of Ecuador are SSW-NNE trending dextral strike-slip faults running parallel to the main subdivisions of the Andes, two major SW-NE dextral strike-slip zones, the Pallatanga and Chingual faults, and north–south trending reverse faults such as the Quito fault. Large earthquakes are common in Ecuador. In the past century, 32 earthquakes M6.0 and larger have occurred within 250 km of this event. On April 16, 2016, a magnitude 7.8 earthquake on the subduction zone interface ~350 km north of the 2023 event resulted in over 600 deaths and over 27,000 injuries.

Earthquake

The earthquake had a magnitude of ṃ6.8 and maximum MMI intensity of VII (Very strong), according to the United States Geological Survey. The European-Mediterranean Seismological Centre reported a magnitude of ṃ6.7. According to PAGER, a service operated by the USGS, damaging shaking of intensities V-VII (Moderate-Very Strong) were felt by 8.41 million people, nearly half of Ecuador's population, including intensity VI (Strong) in Guayaquil.

The earthquake occurred as the result of oblique-slip faulting at an intermediate depth near the subduction interface of the Nazca and South American plates. Its faulting mechanism and depth suggest the event occurred within the subducted lithosphere of the Nazca Plate. Focal mechanism solutions indicate that rupture occurred on either a near vertically dipping fault striking to the southeast or a moderately dipping fault striking to the southwest. At the location of the earthquake, the Nazca plate moves to the east relative to the South American plate at a velocity of about 73 mm (2.9 in) per year. Earthquakes in Ecuador and most of western South America are caused by the strains generated by ongoing subduction.

Events such as this are called intermediate-depth earthquakes, occurring at 70–300 km (43–186 mi) depth. Intermediate-depth earthquakes represent deformation within subducted slabs rather than at the shallow plate interface between subducting and overriding tectonic plates. Typically less damaging on the ground surface above their epicenter than is the case with similar-magnitude shallow-focus earthquakes, but can still be destructive. Large intermediate-depth earthquakes may be felt at large distances from their epicenters.

Impact

Ecuador

Forty-four houses collapsed and a total of 90 houses, 50 schools, 31 health facilities, 14 public infrastructure, 20 private infrastructure, and one bridge were damaged.

In El Oro Province, where numerous houses collapsed, 11 people, including an infant were killed, mostly in the city of Machala. Three people died in the province when a tower collapsed. Two people died in Cuenca; another two were injured; including one person killed when a house façade collapsed onto a car. In Puerto Bolívar, a building housing a museum and a restaurant collapsed into the sea. Collapsed buildings in El Oro Province trapped many people.

Two people were killed in Balao, and one person died in Naranjal. In Guayaquil, 46 buildings and houses were damaged, glass was broken, some walls collapsed, and stores were closed across the city. Three vehicle tunnels in the city were also closed, and one person was injured. In Puná Island, one of the closest areas to the epicenter, 10 houses collapsed. At least 381 people were injured in Ecuador.

Peru

In Tumbes, Peru, a young girl was killed when the roof of a house collapsed. Dozens of people were injured, including some seriously due to landslides. Four houses collapsed, 27 houses, and three health facilities and a barrack were damaged in Zarumilla. 29 people were left homeless and another 73 were affected.

Response

The Ecuadorian Secretariat for Risk Management said firefighters were deployed in search and rescue operations. The National Police conducted damage assessments. President Guillermo Lasso urged citizens to remain calm, adding that "Emergency teams are mobilising to offer all their support to those who have been affected," Toppled power lines interrupting communication and electricity services hampered rescue work. Three facilities of Petroecuador suspended operations temporarily.

See also

• List of earthquakes in 2023
• List of earthquakes in Ecuador