A cryoseism, ice quake or frost quake, [1] [2] [3] [4] is a seismic event caused by a sudden cracking action in frozen soil or rock saturated with water or ice, [5] or by stresses generated at frozen lakes. [6] As water drains into the ground, it may eventually freeze and expand under colder temperatures, putting stress on its surroundings. This stress builds up until relieved explosively in the form of a cryoseism. [1] [7] The requirements for a cryoseism to occur are numerous; [1] [2] therefore, accurate predictions are not entirely possible and may constitute a factor in structural design and engineering when constructing in an area historically known for such events. [5] Speculation has been made between global warming and the frequency of cryoseisms. [8]
Cryoseisms are often mistaken for minor intraplate earthquakes. [5] [9] Initial indications may appear similar to those of an earthquake with tremors, vibrations, ground cracking and related noises, [4] such as thundering or booming sounds. [7] Cryoseisms can, however, be distinguished from earthquakes through meteorological and geological conditions. [5] Cryoseisms can have an intensity of up to VI on the Modified Mercalli Scale. [5] Furthermore, cryoseisms often exhibit high intensity in a very localized area, [4] in the immediate proximity of the epicenter, [9] as compared to the widespread effects of an earthquake. [5] Due to lower-frequency vibrations of cryoseisms, [10] some seismic monitoring stations may not record their occurrence. [9] Cryoseisms release less energy than most tectonic events. [11] Since cryoseisms occur at the ground surface they can cause effects right at the site, enough to jar people awake. [4]
Some reports have indicated the presence of "distant flashing lights" before or during a cryoseism, possibly because of electrical changes when rocks are compressed. [7] Cracks and fissures may also appear as surface areas contract and split apart from the cold. [4] [9] The sometime superficial to moderate occurrences may range from a few centimeters to several kilometers long, with either singular or multiple linear fracturing and vertical or lateral displacement possible. [5]
A glacial cryoseism or glacial ice quake is a non-tectonic seismic event of the glacial cryosphere. A large variety of seismogenic glacial processes arising from internal, ocean calving, or basal processes have been identified and studied. [12] [13] Very large calving events in Greenland and Antarctica have been observed to generate seismic events of magnitude 5 or larger. [14] Extremely large icebergs can also generate seismic signals that are observable at distances up to thousands of kilometers when they collide or grind across the ocean floor. [15] Basal glacial motion be enhanced due to water accumulation underneath a glacier sourced from surface or basal ice melt. Hydraulic pressure of subglacial water can reduce the friction at the bed, allowing the glacier to suddenly shift and generate seismic waves. [10] [16] This type of cryoseism can be very brief, or may last for many minutes. [8]
Geocryological processes were identified as a possible cause of tremors as early as 1818. [1] [5] In the United States, such events have been reported throughout the Midwestern, Northern and Northeastern United States. [1] [7] [17]
Cryoseisms also occur in Canada, [1] [2] especially along the Great Lakes/St. Lawrence corridor, where winter temperatures can shift very rapidly. [18] [19] They have surfaced in Ontario, Quebec, Alberta and the Maritime Provinces. [18] [20] [21]
Glacier-related cryoseism phenomena have been reported in Alaska, [22] Greenland, [23] Iceland (Grímsvötn), [24] Finland, [25] Ross Island, [11] and the Antarctic Prince Charles Mountains. [26]
There are four main precursors for a frost quake cryoseism event to occur: [1] [2]
Cryoseisms typically occur when temperatures rapidly decrease from above freezing to subzero, [4] [9] and are more than likely to occur between midnight and dawn (during the coldest parts of night). [1] [5] However, due to the permanent nature of glacial ice, glacier-related cryoseisms may also occur in the warmer months of summer. [10] In general, cryoseisms may occur 3 to 4 hours after significant changes in temperature. [27] Perennial or seasonal frost conditions involved with cryoseisms limit these events to temperate climates that experience seasonal variation with subzero winters. Additionally, the ground must be saturated with water, which can be caused by snowmelt, rain, sleet or flooding. [5] Geologically, areas of permeable materials like sand or gravel, which are susceptible to frost action, are likelier candidates for cryoseisms. [5] Following large cryoseisms, little to no seismic activity will be detected for several hours, indicating that accumulated stress has been relieved. [27]
An earthquake – also called a quake, tremor, or temblor – is the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they cannot be felt, to those violent enough to propel objects and people into the air, damage critical infrastructure, and wreak destruction across entire cities. The seismic activity of an area is the frequency, type, and size of earthquakes experienced over a particular time. The seismicity at a particular location in the Earth is the average rate of seismic energy release per unit volume.
A glacier is a persistent body of dense ice that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as crevasses and seracs, as it slowly flows and deforms under stresses induced by its weight. As it moves, it abrades rock and debris from its substrate to create landforms such as cirques, moraines, or fjords. Although a glacier may flow into a body of water, it forms only on land and is distinct from the much thinner sea ice and lake ice that form on the surface of bodies of water.
Seismology is the scientific study of earthquakes and the generation and propagation of elastic waves through the Earth or other planetary bodies. It also includes studies of earthquake environmental effects such as tsunamis as well as diverse seismic sources such as volcanic, tectonic, glacial, fluvial, oceanic microseism, atmospheric, and artificial processes such as explosions and human activities. A related field that uses geology to infer information regarding past earthquakes is paleoseismology. A recording of Earth motion as a function of time, created by a seismograph is called a seismogram. A seismologist is a scientist works in basic or applied seismology.
A seismic wave is a mechanical wave of acoustic energy that travels through the Earth or another planetary body. It can result from an earthquake, volcanic eruption, magma movement, a large landslide and a large man-made explosion that produces low-frequency acoustic energy. Seismic waves are studied by seismologists, who record the waves using seismometers, hydrophones, or accelerometers. Seismic waves are distinguished from seismic noise, which is persistent low-amplitude vibration arising from a variety of natural and anthropogenic sources.
An intraplate earthquake is an earthquake that occurs in the interior of a tectonic plate, in contrast to an interplate earthquake on the boundary of a tectonic plate. It is also called an intraslab earthquake, especially when occurring in a microplate.
The New Madrid seismic zone (NMSZ), sometimes called the New Madrid fault line, is a major seismic zone and a prolific source of intraplate earthquakes in the Southern and Midwestern United States, stretching to the southwest from New Madrid, Missouri.
Peak ground acceleration (PGA) is equal to the maximum ground acceleration that occurred during earthquake shaking at a location. PGA is equal to the amplitude of the largest absolute acceleration recorded on an accelerogram at a site during a particular earthquake. Earthquake shaking generally occurs in all three directions. Therefore, PGA is often split into the horizontal and vertical components. Horizontal PGAs are generally larger than those in the vertical direction but this is not always true, especially close to large earthquakes. PGA is an important parameter for earthquake engineering, The design basis earthquake ground motion (DBEGM) is often defined in terms of PGA.
Induced seismicity is typically earthquakes and tremors that are caused by human activity that alters the stresses and strains on Earth's crust. Most induced seismicity is of a low magnitude. A few sites regularly have larger quakes, such as The Geysers geothermal plant in California which averaged two M4 events and 15 M3 events every year from 2004 to 2009. The Human-Induced Earthquake Database (HiQuake) documents all reported cases of induced seismicity proposed on scientific grounds and is the most complete compilation of its kind.
Glacial motion is the motion of glaciers, which can be likened to rivers of ice. It has played an important role in sculpting many landscapes. Most lakes in the world occupy basins scoured out by glaciers. Glacial motion can be fast or slow, but is typically around 25 centimetres per day (9.8 in/d).
Bloop was an ultra-low-frequency, high amplitude underwater sound detected by the U.S. National Oceanic and Atmospheric Administration (NOAA) in 1997. By 2012, earlier speculation that the sound originated from a marine animal was replaced by NOAA's description of the sound as being consistent with noises generated via non-tectonic cryoseisms originating from glacial movements such as ice calving, or through seabed gouging by ice.
The geology of Iceland is unique and of particular interest to geologists. Iceland lies on the divergent boundary between the Eurasian Plate and the North American Plate. It also lies above a hotspot, the Iceland plume. The plume is believed to have caused the formation of Iceland itself, the island first appearing over the ocean surface about 16 to 18 million years ago. The result is an island characterized by repeated volcanism and geothermal phenomena such as geysers.
Earthquake forecasting is a branch of the science of seismology concerned with the probabilistic assessment of general earthquake seismic hazard, including the frequency and magnitude of damaging earthquakes in a given area over years or decades. While forecasting is usually considered to be a type of prediction, earthquake forecasting is often differentiated from earthquake prediction, Earthquake forecasting estimates the likelihood of earthquakes in a specific timeframe and region, while earthquake prediction attempts to pinpoint the exact time, location, and magnitude of an impending quake, which is currently not reliably achievable.Wood & Gutenberg (1935). Kagan says: "This definition has several defects which contribute to confusion and difficulty in prediction research." In addition to specification of time, location, and magnitude, Allen suggested three other requirements: 4) indication of the author's confidence in the prediction, 5) the chance of an earthquake occurring anyway as a random event, and 6) publication in a form that gives failures the same visibility as successes. Kagan & Knopoff define prediction "to be a formal rule where by the available space-time-seismic moment manifold of earthquake occurrence is significantly contracted ...."</ref> Both forecasting and prediction of earthquakes are distinguished from earthquake warning systems, which, upon detection of an earthquake, provide a real-time warning to regions that might be affected.
The 2008 Illinois earthquake was one of the largest earthquakes ever recorded in the Midwest state of Illinois. This moderate strike-slip shock measured 5.2 on the moment magnitude scale and had a maximum Mercalli intensity of VII (Very strong). It occurred at 04:36:59 local time on April 18 near Bellmont and Mount Carmel, Illinois, within the Wabash Valley Seismic Zone. Earthquakes in this part of the country are often felt at great distances.
The 2004 Al Hoceima earthquake occurred on 24 February at 02:27:47 local time near the coast of northern Morocco. The strike-slip earthquake measured 6.3 on the moment magnitude scale and had a maximum perceived intensity of IX (Violent) on the Mercalli intensity scale. Between 628 and 631 people were killed, 926 injured, and up to 15,000 people were rendered homeless in the Al Hoceima-Imzourene-Beni Abdallah area.
The 2002 Bou'in-Zahra earthquake occurred on 22 June 2002. The epicenter was near the city of Bou'in-Zahra in Qazvin Province, a region of northwestern Iran which is crossed by several major faults that is known for destructive earthquakes. The shock measured 6.5 on the Mwc scale, had a maximum Mercalli intensity of VIII (Severe), and was followed by more than 20 aftershocks. At least 230 people were killed and 1,500 more were injured.
Glacial earthquakes refer to a type of seismic event, with a magnitude of about 5, resulting from glacial calving events. The majority of glacial earthquake activity can be seen in the late summer and are found in Antarctica, Alaska, and Greenland. About 90% of these occur in Greenland. Glacial earthquakes occur most frequently in July, August, and September in Greenland. Seismographs are analyzed by scientists to identify and locate glacial earthquakes.
The 1992 Cairo earthquake, also known as the Dahshur earthquake, occurred at 15:09 local time on 12 October, with an epicenter in the Western Desert near Dahshur, Giza, 35 km (22 mi) south of Egypt's capital and most populous city, Cairo. The earthquake had a magnitude of either 5.8 or 5.9, but was unusually destructive for its size, causing 561 deaths and injuring 12,392 people. It also made over 30,000 families homeless in tens of cities and villages across 16 governorates, in Greater Cairo, the Delta, and northern Upper Egypt. It was the most damaging seismic event to affect Egypt since 1847.
The 1887 Sonora earthquake occurred at 22:13 UTC on 3 May in the Teras mountain range of northwestern Mexico. It was widely felt, with some damage being recorded up to 200 kilometers (120 mi) from the epicenter in both Mexico and the United States. The earthquake had an estimated magnitude of 7.6 and caused 42 casualties in the town of Bavispe and 51 overall. It was the only historical earthquake to cause considerable damage in Arizona. The 1887 Tombstone Arizona newspapers mentioned lesser quakes (aftershocks) on August 27, 1887, and November 11, 1887.
This is a list of different types of earthquake.
The 1716 Algiers earthquake was part of a seismic sequence which began in February and ended in May 1716. The largest and most destructive shock occurred on February 3 with an estimated moment magnitude of 7.0. The earthquakes with an epicenter thought to be in the Algiers region had a maximum European macroseismic scale (EMS-98) intensity of IX (Destructive), killing approximately 20,000 people. The earthquake was felt in Catania and Syracuse on the Italian island Sicily.