ICEARRAY
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{{Short description, Icelandic seismic array 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 displacement and shaking such as caused by quakes, volcanic eruptions, and explosions. They are usually combined with a timing device and a recording device to form a seismograph. The out ...
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 a Nordic countries, Nordic island country between the Atlantic Ocean, North Atlantic and Arctic Oceans, on the Mid-Atlantic Ridge between North America and Europe. It is culturally and politically linked with Europe and is the regi ...
. 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 city, capital and largest city in Iceland. It is located in southwestern Iceland on the southern shore of Faxaflói, the Faxaflói Bay. With a latitude of 64°08′ N, the city is List of northernmost items, the worl ...
. The ICEARRAY project is supported by the 6th Framework of the
European Commission The European Commission (EC) is the primary Executive (government), executive arm of the European Union (EU). It operates as a cabinet government, with a number of European Commissioner, members of the Commission (directorial system, informall ...
through the Marie Curie International Re-integration Grant, the Iceland Centre for Research and the
University of Iceland The University of Iceland ( ) 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' school to a modern co ...
Earthquake Engineering Research Centre.


Instruments

The instruments used in the seismic array are CUSP-3Clp
accelerometers An accelerometer is a device that measures the proper acceleration of an object. Proper acceleration is the acceleration (the rate of change of velocity) of the object relative to an observer who is in free fall (that is, relative to an inertia ...
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) is a satellite-based hyperbolic navigation system owned by the United States Space Force and operated by Mission Delta 31. It is one of the global navigation satellite systems (GNSS) that provide geol ...
clock, ensuring a uniform time over the network. The instruments communicate via a wireless permanent
GPRS General Packet Radio Service (GPRS), also called 2.5G, is a mobile data standard on the 2G cellular communication network's Global System for Mobile Communications, global system for mobile communications (GSM). Networks and mobile devices wit ...
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 boundary, divergent or constructive Plate tectonics, plate boundary) located along the floor of the Atlantic Ocean, and part of the List of longest mountain chains on Earth, longest mountai ...
, the extensional
tectonic Tectonics ( via Latin ) are the processes that result in the structure and properties of the Earth's crust and its evolution through time. The field of ''planetary tectonics'' extends the concept to other planets and moons. These processes ...
plate boundary Plate tectonics (, ) is the scientific theory that the Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concept of , an idea developed durin ...
between the North American Plate and the Eurasian Plate. 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 ho ...
known as the
Iceland hotspot The Iceland hotspot is a hotspot that is partly responsible for the high volcanic activity that has formed the Iceland Plateau and the island of Iceland. It contributes to understanding the geological deformation of Iceland. Iceland is one ...
, 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, volcanicity, or volcanic activity is the phenomenon where solids, liquids, gases, and their mixtures erupt to the surface of a solid-surface astronomical body such as a planet or a moon. It is caused by the presence of a he ...
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 194 ...
. 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 earthquakealso called a quake, tremor, or tembloris 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 c ...
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 pri ...
, 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


References


External links


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