Magnitude 5.7 Earthquake in Salt Lake County, Utah.

The United States Geological Survey recorded a Magnitude 5.7 Earthquake at a depth of 11.9 km, about 6 km to the north of the township of Magna in Salt Lake County, Utah, slightly before 7.10 am local time (slightly before 1.10 pm GMT) on Wednesday 18 March 2020. There are no reports of any casualties, but buildings suffered damage across much of the Salt Lake Valley, and significant disruption was caused to electricity, gas, and water supplies due to damaged pipes and cables.

Damage to the Merlin Theatre in Magna, Utah, following a Magnitude 5.7 Earthquake on 18 March 2020. Jeffrey Allred/Deseret News.

The Earthquake occurred on the Intermountain Seismic Belt, a prominent north-south-trending zone of recorded seismicity in the Intermountain West, including the Wasatch Front urban corridor. In northern Utah the Intermountain Seismic Belt forms the transition between east-west-directed stretching in the Basin and Range Province to the west and the more stable crust of the Middle Rocky Mountains to the east. The Intermountain Seismic Belt contains the Wasatch Fault (Utah's most active fault based on geological evidence, though relatively inactive since records began) and many of the state's other most active faults, which commonly show evidence of multiple displacements in the past 10,000 years. Average recurrence intervals for large surface-faulting earthquakes on the most active central segments of the Wasatch fault are 1300-2500 years; recurrence intervals are typically longer (thousands to 10 000 years or more) on other faults in the area.

 The approximate location of the 18 March 2020 Utah Earthquake. USGS.

The Basin and Range Province is particularly associated with tilted block faulting, which occurs as areas of the crust are drawn apart by tectonic activity, causing fracturing in the brittle parts of the lithosphere (near-surface rocks), resulting in the formation of a series of blocks, which are then tilted over by further extension, leading to the formation of a series of active faults.

 The extent of the Basin and Range Province. USGS.

Witness accounts of quakes can help geologists to understand these events and the rock structures that cause them. If you felt this quake (or if you were in the area but did not, which is also useful information) you can report it to the USGS here.

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Explosions on Mount Cameroon.

An explosion on Mount Cameroon is said to have injured two tourist guides working on the mountain on Friday 3 February 2012. Local people also reported seeing bursts of flame and clouds of ash. Residents close to the mountain have reportedly been voluntarily moving away from the volcano, which has a history of violent eruptions.

Lava flow on Mount Cameroon in 1999. Société Volcanologique Européene.

Mount Cameroon is a 4095 m high stratovolcano (cone shaped volcano made up of successive layers of ash and lava) on the coast of Cameroon, about 80 km northwest of the capital, Douala. The volcano sits slightly to the north of the Central African Shear Zone, which cuts though the country from southwest to northeast. The Central African Shear Zone is an extensional structure that initially opened about 640 million years ago; a continuation of the zone is found in South America, where it is called the Pernambuco Fault. It had the potential to develop into a full ocean with a spreading zone at a mid-ocean ridge, similar to the modern Atlatic, but did not develop at that time. It became active again up during the break-up of Gondwanaland (an ancient super-continent of which Africa formed a part) in the Mesozoic, and has been a source of volcanic activity ever since. It could potentially still open into a full ocean as Africa breaks apart in the east along the Great Rift Valley.

Mount Cameroon last erupted in 2000, when lava flows reached to within 5 km of the town of Buea. Plans to evacuate the town were dropped at the last moment when the lava flow stopped abruptly. A cloud of gas and ash was seen to reach 3300 m above the summit of the volcano. The following year the monsoon rains dislodged ash deposits left by the eruption, causing a landslide that struck the coastal city of Limbe, killing 23 people and making about a thousand more homeless.

See also Earthquake shakes Lake Turkana in Kenya, Eruptions on Mount Nyamuragira in the Virunga National Park, Ongoing volcanic activity on El Hierro in the Canary Islands and Volcanoes on Sciency thoughts YouTube.

Earthquakes in the Gulf of California, 26 July 2011.

Just before 11.45 am local time a magnitude 5.9 earthquake struck 10 km beneath the Gulf of California (Sea of Cortez). This was followed by a magnitude 4.3 earthquake slightly before 1.00 pm, then a magnitude 5 quake at 1.40, then a magnitude 4 quake just before 9.45 pm. The quakes occurred roughly 125 NE of La Paz in Baja California State and 100 km SE of Los Mohis in Sinaloa State, Mexico, on the San Andreas Fault. There are no reports of any casualties, and no tsunami warning has been issued.

Map showing the location of the quakes (blue squares) and the San Andreas Fault (red line) in the Gulf of Mexico. From the United States Geological Survey

The San Andreas Fault runs along the length of the Gulf of Mexico, then northward through the US state of California. It is a transform, or strike slip fault caused by two plates (in this case the Pacific and the North American) moving past one another. Faults of this type are not particularly prone to causing tsunamis, but can trigger submarine landslides, which are a tsunami hazard. The main danger from this series of quakes is that by releasing pressure on one part of the fault, they increase it on another; thus the danger of a significant quake in the (populous) US State of California will have now increased.

The San Andreas Fault lies on the border between the north-moving Pacific Plate and the south-moving North American Plate.

The Gulf of Mexico is an extensional basin running along the southern part of the San Andreas Fault. The basin runs on-land as the Imperial Valley of Southern California; for this reason the southern part of the San Andreas Fault is sometimes known as the Imperial Fault. Extensional basins occur where two plates move apart from one-another, in this case the Pacific and North American. Potentially the Gulf of California could one day evolve into a new ocean, though this is not guaranteed, most extensional basins stop expanding before this happens.

See also Torino (Turin) rocked by mild earthquake, Earthquake on the Krygyzstan/Uzbekistan Border and Earthquakes on Sciency Thoughts YouTube.