Interplate earthquake

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An interplate earthquake occurs at the boundary between two tectonic plates. Earthquakes of this type account for more than 90 percent of the total seismic energy released around the world. [1] If one plate is trying to move past the other, they will be locked until sufficient stress builds up to cause the plates to slip relative to each other. The slipping process creates an earthquake with relative displacement on either side of the fault, resulting in seismic waves which travel through the Earth and along the Earth's surface. Relative plate motion can be lateral as along a transform fault boundary, vertical if along a convergent boundary (i.e. subduction or thrust/reverse faulting) or a divergent boundary (i.e. rift zone or normal faulting), and oblique, with horizontal and lateral components at the boundary. Interplate earthquakes associated at a subduction boundary are called megathrust earthquakes, which include most of the Earth's largest earthquakes. [2]

Contents

Intraplate earthquakes are often confused with interplate earthquakes, but are fundamentally different in origin, occurring within a single plate rather than between two tectonic plates on a plate boundary. The specifics of the mechanics by which they occur, as well as the intensity of the stress drop which occurs after the earthquake also differentiate the two types of events. Intraplate earthquakes have, on average, a higher stress drop than that of an interplate earthquake and generally higher intensity. [3]

Mechanics

Mechanically, interplate earthquakes differ from other seismic events in that they are caused by motion at the boundary between two tectonic plates. An interplate earthquake event occurs when the accumulated stress at a tectonic plate boundary are released via brittle failure and displacement along the fault.

There are three types of plate boundaries to consider in the context of interplate earthquake events: [4]

Precursory tremors

Scientists have determined that interplate earthquakes are sometimes preceded by an irregular occurrence of small tremors. [5] Precursory tremors are often associated with slow slip along a plate boundary. [5] These precursory tremors can sometimes be identified within days or weeks of an interplate earthquake event and allow researchers to anticipate interplate earthquakes and introduce strategies to mitigate damage.[ according to whom? ]

Differences with intraplate earthquakes

Beyond the inherent mechanical differences leading to interplate earthquake events and location of interplate earthquakes on plate boundaries, these seismic occurrences can be differentiated by other means.

Intensity

Interplate earthquakes differ from intraplate earthquakes in that the intensity of intraplate earthquakes exceed those of interplate earthquakes by nearly two points. [4] Using the Modified Mercalli Intensity scale, earthquakes are categorized descriptively on a scale from I (not felt) to XII (total destruction) based on observed effects of the seismic event. While the ground accelerations of these two types of events are similar, the resulting intensity of intraplate earthquakes is significantly greater than that of interplate earthquakes [4] due to the greater energy release (stress drop) across intraplate faults.

Stress drop

Stress drop is a measure of the stress across a fault before and after an earthquake rupture. While intraplate and interplate earthquakes obey similar length proportional scaling laws, interplate earthquakes exhibit stress drop values that are systematically smaller by a factor of 6. [6] This suggests that the boundaries between plates are significantly weaker than the plates themselves. [6] The reason for the measurable, systemic difference in stress drop between interplate and intraplate earthquakes is not entirely understood. [6] However, intraplate earthquake models show that stress is distributed uniformly across the fault whereas interplate earthquakes have stress concentrated in specific areas along the boundary. [7] Furthermore, interplate earthquakes release stress immediately, as compared to intraplate earthquakes which release stress gradually. [8]

Effects

Subduction erosion

Basal erosion, the process of removal of materials from the underside of the upper plate by the subducting plate, occurs at numerous, but not all, convergent margins. As the process of subduction erosion is not completely understood, a model has been proposed in which basal erosion is supplemented by cyclical, interplate earthquakes. [9] The model suggests that erosion does not occur gradually in subduction zones, but rather in brief episodes of elevated seismicity along the plate boundary.

Tsunamis

Earthquakes are a major factor in the creation of tsunami waves. As interplate earthquakes result in an immediate release of stress along a fault, they produce significant seismic energy and can cause seafloor uplift, generating large waves as the energy from the sudden slip along the fault is transferred to the overlying water body. However, the majority of interplate earthquakes are not intense enough to create tidal waves, with most tsunamis being caused by intraplate earthquakes or tsunami earthquakes due to their comparatively slow stress release regimes and proximity to the surface of the Earth. [10]

Major interplate earthquakes

Interplate earthquakes account for over 90% of all seismic energy released worldwide. [1] As such, their effects are widespread and interplate earthquake events are numerous. Earthquakes of magnitudes higher than 5 in populated regions are considered highly dangerous and pose a direct threat to human life and property. [4] Some of the largest, most devastating earthquakes that have occurred in the last century have been identified as interplate events. Some areas of the world that are particularly prone to interplate earthquakes due to the presence of prominent plate boundaries include the west coast of North America (especially California and Alaska), the northeastern Mediterranean region (Greece, Italy, and Turkey in particular), Iran, New Zealand, Indonesia, India, Japan, and parts of China.

Major earthquakes (magnitude ≥ 9.0) since 1900 [11]
DateLatitudeLongitudeDepth (km)MagnitudeLocation
2011-03-11 38.297142.373299.1near the east coast of Honshu, Japan
2004-12-26 3.29595.982309.1off the west coast of northern Sumatra
1964-03-28 60.908−147.339259.2Southern Alaska
1960-05-22 −38.143−73.407259.5Bio-Bio, Chile
1952-11-04 52.62359.77921.69off the east coast of the Kamchatka Peninsula, Russia

Major earthquakes (magnitude ≥ 9.0) since 1900 [11]

Interplate earthquake

See also

Related Research Articles

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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.

<span class="mw-page-title-main">Intraplate earthquake</span> Earthquake that occurs within the interior of a tectonic plate

An intraplate earthquake occurs in the interior of a tectonic plate, in contrast to an interplate earthquake on the boundary of a tectonic plate. They are relatively rare compared to the more familiar interplate earthquakes. Buildings far from plate boundaries are rarely protected with seismic retrofitting, so large intraplate earthquakes can inflict heavy damage. Examples of damaging intraplate earthquakes are the devastating 2001 Gujarat earthquake, the 2011 Christchurch earthquake, the 2012 Indian Ocean earthquakes, the 2017 Puebla earthquake, the 1811–1812 New Madrid earthquakes, and the 1886 Charleston earthquake. An earthquake that occurs within a subducting plate is known as an intraslab earthquake.

<span class="mw-page-title-main">Convergent boundary</span> Region of active deformation between colliding tectonic plates

A convergent boundary is an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a plane where many earthquakes occur, called the Wadati–Benioff zone. These collisions happen on scales of millions to tens of millions of years and can lead to volcanism, earthquakes, orogenesis, destruction of lithosphere, and deformation. Convergent boundaries occur between oceanic-oceanic lithosphere, oceanic-continental lithosphere, and continental-continental lithosphere. The geologic features related to convergent boundaries vary depending on crust types.

<span class="mw-page-title-main">Japan Trench</span> Oceanic trench part of the Pacific Ring of Fire off northeast Japan

The Japan Trench is an oceanic trench part of the Pacific Ring of Fire off northeast Japan. It extends from the Kuril Islands to the northern end of the Izu Islands, and is 8,046 metres (26,398 ft) at its deepest. It links the Kuril–Kamchatka Trench to the north and the Izu–Ogasawara Trench to its south with a length of 800 kilometres (497 mi). This trench is created as the oceanic Pacific plate subducts beneath the continental Okhotsk microplate. The subduction process causes bending of the down going plate, creating a deep trench. Continuing movement on the subduction zone associated with the Japan Trench is one of the main causes of tsunamis and earthquakes in northern Japan, including the megathrust Tōhoku earthquake and resulting tsunami that occurred on 11 March 2011. The rate of subduction associated with the Japan Trench has been recorded at about 7.9–9.2 centimetres (3.1–3.6 in)/yr.

<span class="mw-page-title-main">Cascadia subduction zone</span> Convergent plate boundary that stretches from northern Vancouver Island to Northern California

The Cascadia subduction zone is a 960 km (600 mi) fault at a convergent plate boundary, about 100–200 km (70–100 mi) off the Pacific coast, that stretches from northern Vancouver Island in Canada to Northern California in the United States. It is capable of producing 9.0+ magnitude earthquakes and tsunamis that could reach 30 m (98 ft). The Oregon Department of Emergency Management estimates shaking would last 5–7 minutes along the coast, with strength and intensity decreasing further from the epicenter. It is a very long, sloping subduction zone where the Explorer, Juan de Fuca, and Gorda plates move to the east and slide below the much larger mostly continental North American plate. The zone varies in width and lies offshore beginning near Cape Mendocino, Northern California, passing through Oregon and Washington, and terminating at about Vancouver Island in British Columbia.

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<span class="mw-page-title-main">Kamchatka earthquakes</span> Earthquakes in the Kamchatka Peninsula, far eastern Russia

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<span class="mw-page-title-main">Aleutian Trench</span> An oceanic trench along the southern coastline of Alaska and the Aleutian islands

The Aleutian Trench is an oceanic trench along a convergent plate boundary which runs along the southern coastline of Alaska and the Aleutian islands. The trench extends for 3,400 kilometres (2,100 mi) from a triple junction in the west with the Ulakhan Fault and the northern end of the Kuril–Kamchatka Trench, to a junction with the northern end of the Queen Charlotte Fault system in the east. It is classified as a "marginal trench" in the east as it runs along the margin of the continent. The subduction along the trench gives rise to the Aleutian Arc, a volcanic island arc, where it runs through the open sea west of the Alaska Peninsula. As a convergent plate boundary, the trench forms part of the boundary between two tectonic plates. Here, the Pacific plate is being subducted under the North American plate at a dip angle of nearly 45°. The rate of closure is 7.5 centimetres (3 in) per year.

At 20:55 PET on 25 September 2005, an earthquake measuring Mw  7.5 or ML  7.0 struck the Department of Loreto in Peru, resulting in 20 fatalities and 266 injuries, with 1,316 homes damaged or destroyed, mostly in the town of Lamas. It had a maximum perceived intensity of VI (Strong) on the Modified Mercalli Intensity Scale.

A slow earthquake is a discontinuous, earthquake-like event that releases energy over a period of hours to months, rather than the seconds to minutes characteristic of a typical earthquake. First detected using long term strain measurements, most slow earthquakes now appear to be accompanied by fluid flow and related tremor, which can be detected and approximately located using seismometer data filtered appropriately. That is, they are quiet compared to a regular earthquake, but not "silent" as described in the past.

The 1992 Cape Mendocino earthquakes occurred along the Lost Coast of Northern California on April 25 and 26. The three largest events were the M7.2 thrust mainshock that struck near the unincorporated community of Petrolia midday on April 25 and two primary strike-slip aftershocks measuring 6.5 and 6.6 that followed early the next morning. The sequence encompassed both interplate and intraplate activity that was associated with the Mendocino triple junction, a complex system of three major faults that converge near Cape Mendocino. The total number of aftershocks that followed the events exceeded 2,000.

The 1935 Sumatra earthquake occurred at 09:35 local time on 28 December. It had a magnitude of Mw 7.7 and a maximum felt intensity of VII (Damaging) on the European macroseismic scale. It triggered a minor tsunami.

This is a list of different types of earthquake.

The 1981 Playa Azul earthquake occurred on October 24, 1981, at 21:22 local time. It was located near Playa Azul, Michoacán, Mexico. The magnitude of the earthquake was Mw 7.2, or Ms 7.3. Three deaths were reported, two from Michoacán and one from Mexico City. Some buildings were damaged in both Michoacán and Mexico City. A small tsunami was registered in Acapulco with a maximum height of 9 cm.

The 1965 Valparaíso earthquake struck near La Ligua in Valparaíso Region, Chile, about 140 km (87 mi) from the capital Santiago on Sunday, March 28 at 12:33 local time. The moment magnitude (Mw ) 7.4–7.6 earthquake killed 400–500 people and inflicted US$1 billion in damage. Many deaths were from El Cobre, a mining location that was wiped out after a series of dam failures caused by the earthquake spilled mineral waste onto the area, burying hundreds of residents. The shock was felt throughout the country and along the Atlantic coast of Argentina.

On January 30, 1973, at 15:01 (UTC–6), a magnitude 7.6 earthquake struck 35.3 km (21.9 mi) 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.

The 1852 Banda Sea earthquake struck on 26 November at 07:40 local time, affecting coastal communities on the Banda Islands. It caused violent shaking lasting five minutes, and was assigned XI on the Modified Mercalli intensity scale in the Maluku Islands. A tsunami measuring up to 8 m (26 ft) slammed into the islands of Banda Neira, Saparua, Haruku and Ceram. The tsunami caused major damage, washing away many villages, ships and residents. At least 60 people were killed in the earthquake and tsunami. The earthquake had an estimated moment magnitude of 7.5 or 8.4–8.8, according to various academic studies.

<span class="mw-page-title-main">2021 Chignik earthquake</span> 7th largest earthquake in the US

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The 2021 Loyalty Islands earthquake was a 7.7 magnitude earthquake that struck offshore between Vanuatu and New Caledonia on February 11, 2021, at 00:19 local time. It is the 4th largest earthquake of 2021.

The 1843 Nias earthquake off the northern coast of Sumatra, Indonesia caused severe damage when it triggered a tsunami along the coastline. The earthquake with a moment magnitude (Mw ) of 7.8 lasted nine minutes, collapsing many homes in Sumatra and Nias. It was assigned a maximum modified Mercalli intensity of XI (Extreme).

References

  1. 1 2 Bolt, Bruce (August 2005), Earthquakes: 2006 Centennial Update – The 1906 Big One (Fifth ed.), W. H. Freeman and Company, p. 150, ISBN   978-0716775485
  2. ↑ Hardebeck, Jeanne L. (11 September 2015). "Stress orientations in subduction zones and the strength of subduction megathrust faults". Science. 349 (6253): 1213–1216. doi:10.1126/science.aac5625. PMID   26359399. S2CID   6190394.
  3. ↑ Kato, Naoyuki (December 2009). "A possible explanation for difference in stress drop between intraplate and interplate earthquakes". Geophysical Research Letters. 36 (23): L23311. Bibcode:2009GeoRL..3623311K. doi:10.1029/2009gl040985. S2CID   129296599.
  4. 1 2 3 4 Bellam, S. S. (2012). Assessment of Interplate and Intraplate Earthquakes (Doctoral dissertation, Texas A & M University).
  5. 1 2 Bouchon, Michel; Durand, Virginie; Marsan, David; Karabulut, Hayrullah; Schmittbuhl, Jean (2013), "The long precursory phase of most large interplate earthquakes", Nature Geoscience, 6 (4): 299–302, Bibcode:2013NatGe...6..299B, doi:10.1038/ngeo1770
  6. 1 2 3 Scholz, C. H., Aviles, C. A., & Wesnousky, S. G. (1986). Scaling differences between large interplate and intraplate earthquakes. Bulletin of the Seismological Society of America, 76(1), 65–70.
  7. ↑ Kato, N. (2009). A possible explanation for difference in stress drop between intraplate and interplate earthquakes. Geophysical Research Letters,36(23). doi:10.1029/2009gl040985
  8. ↑ Li, Qingson; Liu, Mian; Zhang, Qie; Sandvol, Eric (2007), "Stress evolution and seismicity in the central-eastern United States: Insights from geodynamic modeling", Continental Intraplate Earthquakes: Science, Hazard, and Policy Issues, 425: 153, doi:10.1130/2007.2425(11), ISBN   978-0-8137-2425-6
  9. ↑ Wang, K., Hu, Y., Huene, R. V., & Kukowski, N. (2010). Interplate earthquakes as a driver of shallow subduction erosion. Geology,38(5), 431–434. doi:10.1130/g30597.1
  10. ↑ "Earthquake | Intra and Inter-plate seismic events". sms-tsunami-warning.com. Retrieved 2018-05-26.
  11. 1 2 "USGS Earthquake Hazards Program". United States Geological Survey. Retrieved 2018-05-31.
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