57 documents found in 243ms
# 1
GEOFON Data Centre
Abstract: GEOFON (GEOFOrschungsNetz) is the global seismological broad-band network operated by the German GeoForschungsZentrum (GFZ). The GEOFON seismic network came into being in 1993 as one of the three pillars of the GEOFON program dedicated to Ernst von Rebeur-Paschwitz, proposer of a global earthquake monitoring system, who recorded the first teleseismic seismogram in Potsdam in 1889. The program and its seismic network were created to provide high quality broad-band data for scientific use and foster common standards in the seismological community. The network has evolved towards real-time data acquisition and distribution while keeping the high quality broad-band data in focus. Today the network plays a leading role in global real-time seismology providing valuable data for almost all fundamental and applied global/regional seismological research projects at GFZ and the wider seismological community. The GEOFON network is operated jointly with more than 50 international partners and in 2014 consists of about 80 active stations on all continents, but concentrated in Europe and the Mediterranean region as well as in the Indian Ocean. Station operation is mostly performed by local partners with GFZ guidance and logistic support, allowing the global network to be well-advanced technically while still extremely cost-effective. All stations are equipped with broad-band sensors (generally STS-2) that allow resolution of the complete seismic spectrum from small high-frequency local earthquakes to the largest global earthquakes. Data from all stations are freely redistributed in real-time for earthquake monitoring and tsunami warning centers immediately after acquisition at the GEOFON data centre via wired or satellite links. Archived data is also available. GEOFON is part of the Modular Earth Science Infrastructure (MESI) housed at GFZ.
# 2
Asch, Guenter • Tilmann, Frederik • Schurr, Bernd • Ryberg, Trond
Abstract: The integrated plate boundary in Chile (IPOC) combines 15 broadband stations with strong-motion sensors, GPS, strain sensors and magneto-telluric stations. The Chilean subduction zone setting provides a high background rate of seismicity (crustal, intermediate depth, and plate interface) in a region with exceptionally low ambient noise, particularly at higher frequencies. We have deployed seismic mini-arrays in the vicinity of IPOC stations PB02 and PB07, and installed a third array to the east of these stations near the village of Quillagua, such that all three arrays form a triangle. Each array has 10 elements and an aperture in the km range. The study area lies just to the north of the northern boundary of the rupture area of the Tocopilla earthquake of 2007 (Mw=7.7) and just above or slightly to the east of the downdip limit of plate interface seismicity. Installing the mini-arrays in the area of the existing IPOC has the following advantages: * Independent knowledge of background structure and seismicity from existing and ongoing studies. * Should any transients or other unusual signals be found in the array data, we can look for anomalous signals in geodetic and MT recordings, which will help to narrow down possible underlying mechanisms.
# 3
Heit, Ben • Yuan, Xiaohui • Jokat, Wilfried • Weber, Michael • Geissler, Wolfram
Abstract: The Etendeka continental flood-basalt province in northern Namibia, linked by the Walvis Ridge to the Tristan da Cunha hotspot, has great importance in global plate tectonic concepts, and is an ideal place to understand the role of the plume-lithosphere interaction during the break-up of the Southern Atlantic Ocean. Within this frame we operated an amphibian passive-source seismic network (WALPASS for Walvis Ridge Passive Source Experiment) in the region where the Walvis Ridge intersects with the continental margin of northern Namibia. The land network operated for over two years while the OBS stations were in operation for one year. The broadband seismic network is composed of 28 three-component land stations and 12 ocean-bottom stations. This configuration of stations will allow us to map the lithospheric and upper mantle structure in the ocean-continent transition beneath the passive continental margin of northern Namibia and to examine possible seismic anomalies related to the postulated hotspot track from the continent to the ocean along the Walvis Ridge. The acquired data should help clarify the velocity anomaly in the lowermost mantle caused by the Africa super plume and to improve the distribution of seismicity in this geophysically little studied region.
# 4
Ryberg, Trond • Haberland, Christian
Abstract: The Toba caldera is located in north Sumatra, Indonesia. It is part of the volcanic arc associated with the subduction of the Australian Plate beneath the Southeast-Asian Plate. The subduction zone, and the Sumatra Fault, a right lateral strike-slip fault which marks the plate boundary, are seismically active. In order to investigate the volcano-related seismic activity and image the volcano related structures (i.e. a potential magma chamber) using ambient noise techniques a dense seismic network was installed around Lake Toba between May and October 2008. The network, deployed within a German-Indonesian cooperation, comprised 42 continuously recording seismic stations equipped with three-component, short-period seismic sensors with 1 Hz natural frequency. The GPS-synchronised data loggers recorded at 100 samples per second for the experiment's time span of 6 months. During this time period local and regional seismicity was recorded. The array of stations covers an area of approx. 150 by 200 km with inter-station distances of about 20 km. The station distribution is quite irregular due to the difficult environmental conditions. Data from all stations are freely available from the GFZ seismological data archive.
# 5
Roessler, Dirk • Hiemer, Stefan • Bach, Christoph • Delavaud, Elise • Krueger, Frank • (et. al.)
Abstract: Earthquake swarms occur frequently in Vogtland/West Bohemia at the German-Czech border. The link between these earthquakes and magmatic fluids that escape at the surface has been debated and investigated. The Rohrbach/Vogtland seismic array, installed by the University of Potsdam, Germany, was a small-aperture array that monitored the major earthquake swarm in 2008 and the background seismicity between October 16, 2008 and March 18, 2009. The array consisted of 11 stations equipped with MarsLite data loggers and Lennartz Le3D-5s seismometers. Data were recorded in continuous mode at 250 Hz. Sensors were buried in the ground at 0.5 m depth. High-precision station coordinates were obtained using differential GPS measurements. The array data has been used for analyses of earthquakes and seismic structures. Waveform data is fully open.
# 6
Passarelli, Luigi • Roessler, Dirk • Aladino, Govoni • Maccaferri, Francesco • Moretti, Milena • (et. al.)
Abstract: The temporary Pollino Seismic Experiment, FDSN network code 4A, monitored the earthquake swarm in the Pollino Range region, Italy, between November 2012 and September 2014. The region is located at the transition from the Southern Apennines chain to the Calabrian arc. Striking a volume of about 20x20x15 km, the swarm started in October 2010, culminated in an Mw=5.2 event on 25 October 2012, and has continued since with a variable rate of activity. The area represents a seismic gap as there are no documented historical M>6 earthquakes during the last thousand years. The tectonic structures of the area are poorly known. The experiment was part of a collaborative effort made by the German Research Centre for Geosciences (GFZ) and the Istituto Nazionale di Geofisica e Vulcanologia (INGV) within the framework of the NERA and CCMP-Pompei projects. The 4A network consisted of 9 stations including 6 short-period and 3 broadband instruments, provided by GFZ. The permanent seismic network was complemented by the 9 GFZ stations and 5 IV stations temporarily installed by INGV. The short-period stations had Mark L-4C3D sensors with EDL digitizers. The broadband stations were equipped with STS2.5 seismometers and RefTek RT130S digitizers. Five short period and one broadband (CSA0 to CSA5) were installed in a small-aperture array in the west of the range. The other three stations (broadband: CSB, CSC and short period: CSD) were installed around the swarm area. The array and the network stations recorded in continuous mode at 200 Hz and at 100 Hz, respectively. The sensors were buried in the ground at 0.5 m depth except for CSB and CSD which were installed on the surface. High-precision station coordinates were obtained by using differential GPS measurements. The data have been used to analyze the earthquakes and seismogenetic structures and to discern the characteristics of the swarm sequence.
# 7
Roessler, Dirk • Passarelli, Luigi • Govoni, Aladino • Bautz, Ralf • Dahm, Torsten • (et. al.)
Abstract: The temporary Extended Pollino Seismic Experiment (FDSN network code Y4) monitored the earthquake swarm in the Pollino Range region, Italy, between September 2014 and April 2015. The experiment followed the Pollino Seismic Experiment, 2012-2014 (network code: 4A) [1] in the same area, further enhancing the detection and analysis capabilities there. It was part of a collaborative effort made by the German Research Centre for Geoscience (GFZ) and the Istituto Nazionale di Geofisica e Vulcanologia (INGV) within the CCMP-Pompei, FEFI and NERA projects. The Pollino Range region is located at the transition from the Southern Apennines chain to the Calabrian arc. Striking a volume of about 20x20x15 km, the swarm started in October 2010, culminated in a Mw=5.2 on 25 October 2012 and has continued since with a variable rate of activity. The area represents a seismic gap as there are no documented historical M>6 earthquakes during the last thousand years. The tectonic structures of the area are poorly known. The Y4 network consisted of 19 stations including 14 broadband and five short-period instruments. All instruments were provided by the Geophysical Instrument Pool Potsdam (GIPP) and the CCMP-Pompei project at GFZ and INGV. They were complemented by another four temporary IV stations installed by INGV. The short-period stations had Mark L-4C3D sensors with EDR digitizers. The broadband stations were equipped with STS2.5 seismometers and RefTek RT130S digitizers or Güralp CMG-ESP or Güralp CMG-40T seismometers and EDR digitizers. Eleven broadband (CSA0 to CSA10) were installed in a small-aperture detection array in the west of the range. The other 8 stations (broadband: CSB, CSE, CSD0 and short period: CSF, CSG, CSH, CSI, CSK) formed a network in the swarm area. The array and the network stations recorded in continuous mode at 200 Hz. The sensors were buried in the ground at 0.5 m depth except for CSB, CSE and CSD0 which were installed on the surface. High-precision station coordinates were obtained by using differential GPS measurements. The data have been used to analyze the earthquakes and seismogenetic structures and to discern the characteristics of the swarm sequence. Waveform data will be fully open after April 2017. [1] Pollino Seismic Experiment, 2012-2014, doi:10.14470/9N904956
# 8
Wilde-Piórko, Monika • Geissler, Wolfram H. • Plomerová, Jaroslava • Knapmeyer-Endrun, Brigitte • Grad, Marek • (et. al.)
Abstract: The Teisseyre-Tornquist Zone (TTZ) as part of the Trans-European Suture Zone (TESZ) is one of the most prominent suture zones in Europe separating the young Palaeozoic platform from the much older Precambrian East European craton. The knowledge of deep structure of the TESZ is very important for the understanding of various tectonic processes in Europe. The PASSEQ 2006-2008 seismic experiment was performed thanks to a big international effort of 17 institutions from 10 countries. A total of 139 three-component temporary short-period and 49 temporary broadband seismic stations provided continuous recordings between May 2006 and June 2008 with the main period of recordings during 2007, in an array about 1200 km long and 400 km wide running from Germany through the Czech Republic and Poland to Lithuania. The average spacing between all stations was about 60 km, attaining about 20 km in the central part. The configuration of the seismic network was a compromise among needs of different seismic methods. The dense central profile allows the use of modern passive 2-D imaging techniques, while the distribution of broadband sensors was designed for surface wave and receiver function studies of the upper mantle down to the transition zone in a wide frequency range. Waveform data is fully open, with network code 7E.
# 9
GFZ German Research Centre for Geosciences • Institut des Sciences de l’Univers-Centre National de la Recherche CNRS-INSU
Abstract: The IPOC seismic network is part of the Integrated Plate boundary Observatory Chile (IPOC), a European-Chilean network of institutions and scientists organizing and operating a distributed system of instruments and projects dedicated to the study of earthquakes and deformation at the continental margin of Chile. In particular, the seismic network is jointly operated by the GFZ German Research Centre for Geosciences, Potsdam, Germany; the Institut de Physique du Globe Paris, France (IPGP); the Chilean National Seismological Centre (CSN); the Universidad de Chile, Santiago, Chile (UdC); and the Universidad Católica del Norte, Antofagasta, Chile (UCNA). The subduction plate boundary between the South American and the oceanic Nazca plates exhibits some of the largest earthquakes on Earth. The IPOC goal is to improve the understanding of both the physical mechanisms underlying these processes and the natural hazards induced by them. The observatory is designed to monitor the plate boundary system from the Peru-Chile border to south of the city of Antofagasta, from the coast to the high Andes, capturing both great and small earthquakes in this region. A key component of IPOC is its multi-parameter observatories, where at each site a suite of different physical parameters are measured continuously. So far about 20 such multi-parameter stations are installed. All of these sites are equipped with STS-2 broadband seismometers and accelerometers. Additional instrumentation at some of the stations includes continuous GPS, electric and magnetic field (MT), surface inclination, and climate (temperature, air pressure, humidity). Most sites transmit their data in near-real time using a suite of communication channels (VSAT, WiFi, telemetry etc.). Seismic instruments are deployed on concrete pedestals in bedrock caverns (a few meters deep) to measure ground shaking from earthquakes or other sources that last from a tiny fraction of a second to several hours. Strong-motion sensors are deployed next to the broadband sensors to increase the dynamic range and for earthquake engineering applications. Broadband data are freely distributed in real-time and archive data is also available. This DOI encompasses all IPOC seismic data; data is available under FDSN network code CX.
# 10
Tilmann, Frederik • Yuan, Xiaohui • Rümpker, Georg • Rindraharisaona, Elisa
Abstract: The island of Madagascar occupies a key region in both the assembly and the multi-stage breakup of Gondwanaland, itself part of the super-continent Pangaea. Madagascar consists of an amalgamation of continental material, with the oldest rocks being of Archaean age. Its ancient fabric is characterised by several shear zones, some of them running oblique to the N-S trend, in particular in the south of the island. More recently during the Neogene, moderate volcanism has occurred in the Central and Northern part of the island, and there are indications of uplift throughout Eastern Madagascar over the last 10 Ma. Although Madagascar is now located within the interior of the African plate and far away from major plate boundaries (>1000 km from the East African rift system and even further from the Central and South-West Indian Ridges), its seismic activity indicates that some deformation is taking place, and present-day kinematic models based on geodetic data and earthquake moment tensors in the global catalogues identify a diffuse N-S-oriented minor boundary separating two microplates, which appears to pass through Madagascar. In spite of the presence of Archaean and Proterozoic rocks continent-wide scale studies indicate a thin lithosphere (<120 km) throughout Madagascar, but are based on sparse data and cannot resolve the difference between eastern and western Madagascar. We have operated an ENE-WSW oriented linear array of 25 broadband stations in southern Madagascar, extending from coast to coast and sampling the sedimentary basins in the west as well as the metamorphic rocks in the East, cutting geological boundaries seen at the surface at high angle. The array crosses the prominent Bongolava-Ranotsara shear zone which is thought to have been formed during Gondwanaland assembly. The array recorded the magnitude 5.3 earthquake of January 25, 2013 which occurred just off its western edge. In addition, in May 2013 we have deployed 25 short period sensors in the eastern part of the study area, where there is some so-far poorly characterised seismicity. Waveform data is available from the GEOFON data centre, under network code ZE, and is embargoed until DEC 2018.
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