ICEARRAY is an abbreviation for Icelandic Strong-motion Array. The ICEARRAY network is a seismic array of 14 strong-motion stations located within the South Iceland Seismic Zone. Each station consists of a

seismograph A seismometer is an instrument that responds to ground noises and shaking such as caused by earthquakes, volcanic eruptions, and explosions. They are usually combined with a timing device and a recording device to form a seismograph. The output ...

situated in a protective housing. The stations are spread across a geographical area of approximately 3 km² in the town of Hveragerdi in south-western

Iceland Iceland ( is, Ísland; ) is a Nordic island country in the North Atlantic Ocean and in the Arctic Ocean. Iceland is the most sparsely populated country in Europe. Iceland's capital and largest city is Reykjavík, which (along with its s ...

. Most of the units are located in the basements of residential buildings in Hveragerdi town centre, which is approximately 35 km southeast of Iceland's capital,

Reykjavík Reykjavík ( ; ) is the capital and largest city of Iceland. It is located in southwestern Iceland, on the southern shore of Faxaflói bay. Its latitude is 64°08' N, making it the world's northernmost capital of a sovereign state. With a po ...

. The ICEARRAY project is supported by the 6th Framework of the

European Commission The European Commission (EC) is the executive of the European Union (EU). It operates as a cabinet government, with 27 members of the Commission (informally known as "Commissioners") headed by a President. It includes an administrative body o ...

through the Marie Curie International Re-integration Grant, the Iceland Centre for Research and the

University of Iceland The University of Iceland ( is, Háskóli Íslands ) is a public research university in Reykjavík, Iceland and the country's oldest and largest institution of higher education. Founded in 1911, it has grown steadily from a small civil servants' s ...

Earthquake Engineering Research Centre.

Instruments

The instruments used in the seismic array are CUSP-3Clp

accelerometers An accelerometer is a tool that measures proper acceleration. Proper acceleration is the acceleration (the rate of change of velocity) of a body in its own instantaneous rest frame; this is different from coordinate acceleration, which is accele ...

manufactured by Canterbury Seismic Instruments Ltd. based in New Zealand. The instruments record three components of ground motion, i.e. one vertical and two horizontal components, over a high dynamic range.Halldórsson B, Sigbjörnsson R and Schweitzer J (2008) ICEARRAY: the first small-aperture, strong-motion array in Iceland. ''Journal of Seismology'', DOI 10.1007/s10950-008-9133-z The instruments are connected to a

GPS The Global Positioning System (GPS), originally Navstar GPS, is a Radionavigation-satellite service, satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of t ...

clock, ensuring a uniform time over the network. The instruments communicate via a wireless permanent

GPRS General Packet Radio Service (GPRS) is a packet oriented mobile data standard on the 2G and 3G cellular communication network's global system for mobile communications (GSM). GPRS was established by European Telecommunications Standards Insti ...

connection. This enables remote configuration of individual units and near real-time alerts and data uploading. An important feature that has been developed during the establishment of the array is a common triggering scheme. This feature was designed in collaboration with the manufacturers of the units. In the event of two or more units receiving an earthquake trigger, the common triggering feature activates the entire array to start recording. This scheme ensures complete data coverage and greatly reduces the need to filter out noise and manmade disturbances.

Geographical location

Iceland is located on the

Mid-Atlantic Ridge The Mid-Atlantic Ridge is a mid-ocean ridge (a divergent or constructive plate boundary) located along the floor of the Atlantic Ocean, and part of the longest mountain range in the world. In the North Atlantic, the ridge separates the North Ame ...

, the extensional

tectonic Tectonics (; ) are the processes that control the structure and properties of the Earth's crust and its evolution through time. These include the processes of mountain building, the growth and behavior of the strong, old cores of continents k ...

plate boundary Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large te ...

between the

North American Plate The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the Pacific ...

and the

Eurasian Plate The Eurasian Plate is a tectonic plate that includes most of the continent of Eurasia (a landmass consisting of the traditional continents of Europe and Asia), with the notable exceptions of the Indian subcontinent, the Arabian subcontinent and ...

. It is also located over a deep-seated

mantle plume A mantle plume is a proposed mechanism of convection within the Earth's mantle, hypothesized to explain anomalous volcanism. Because the plume head partially melts on reaching shallow depths, a plume is often invoked as the cause of volcanic hot ...

known as the

Iceland hotspot The Iceland hotspot is a hotspot which is partly responsible for the high volcanic activity which has formed the Iceland Plateau and the island of Iceland. Iceland is one of the most active volcanic regions in the world, with eruptions occur ...

, which causes dynamic uplift of the

Iceland Plateau The Iceland Plateau or Icelandic Plateau is an oceanic plateau in the North Atlantic Ocean consisting of Iceland and its contiguous shelf and marginal slopes. The landscape is constantly experiencing deformation due to the continual addition of ma ...

, with associated

volcanism Volcanism, vulcanism or volcanicity is the phenomenon of eruption of molten rock (magma) onto the surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics, and volcanic gases erupt through a break in the surface called ...

and

seismicity Seismicity is a measure encompassing earthquake occurrences, mechanisms, and magnitude at a given geographical location. As such, it summarizes a region's seismic activity. The term was coined by Beno Gutenberg and Charles Francis Richter in 19 ...

. The line of the Mid-Atlantic Ridge is offset by two transform zones in Iceland, the South Iceland Seismic Zone (SISZ) in the south and the Tjornes Fracture Zone in the north. The town of Hveragerdi is located at the western end of the SISZ, an area of considerable seismicity.

Background

The South Iceland Seismic Zone (SISZ) has been the location of numerous large destructive

earthquakes An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from ...

in the past. The SISZ is an east-west trending transform zone approximately 70 km long and 10–20 km wide. Destructive earthquake sequences in this region usually consist of several earthquakes exceeding a

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

of 6.5 and with their epicentres located on north-south trending faults. Such a sequence started on 17 June 2000 at 15:40 local time with an earthquake of magnitude 6.5. It was followed on 21 June 2000 at 00:51 by a magnitude 6.4 event. Earthquake-induced damage was widespread, although fortunately there was no loss of life and no serious injuries.

Purpose

The potential of these large destructive earthquakes occurring is a constant threat to local and national

infrastructure Infrastructure is the set of facilities and systems that serve a country, city, or other area, and encompasses the services and facilities necessary for its economy, households and firms to function. Infrastructure is composed of public and priv ...

, such as pipelines, electrical power transmission, roads, dams and bridges. The

spatial variability Spatial variability occurs when a quantity that is measured at different spatial locations exhibits values that differ across the locations. Spatial variability can be assessed using spatial descriptive statistics such as the range. Let us sup ...

of earthquake ground motions is a key aspect when designing infrastructure. It can have a dramatic effect on the response of structures and the extent of damage.Zanardo G, Hao H, Modena C (2002) Seismic response of multi-span simply supported bridges to a spatially varying earthquake ground motion. ''Earthquake Engineering and Structural Dynamics'' 31: 1325–1345 In order to estimate the effects, it is necessary to develop models from data recorded on a seismograph array. This is the reason why the ICEARRAY was created. The models developed from the data recorded on the ICEARRAY have enabled the first reliable assessment of earthquake effects on infrastructure in the SISZ. The data also provides a physically realistic description of fault rupture. The models and simulations developed can be applied in other regions and the methods used provide a link between seismology and

earthquake engineering Earthquake engineering is an interdisciplinary branch of engineering that designs and analyzes structures, such as buildings and bridges, with earthquakes in mind. Its overall goal is to make such structures more resistant to earthquakes. An earth ...

References

External links

ICEARRAY websiteEarthquake Engineering Research Centre websiteCanterbury Seismic Instruments website
Earthquake and seismic risk mitigation Earthquake engineering