6 documents found in 136ms
# 1
Passarelli, Luigi • Heryandoko, Nova • Muzli • Rasmid • Zimmer, Martin • (et. al.)
Abstract: The Halmahera island belongs to the North Moluccas province (Maluku Utara), Indonesia. This K-shaped island is located in the eastern part of the Moluccas Sea, the only active arc-arc collision complex on the Earth. The western arm of the K forms a volcanic arc due to the former subduction of the Moluccas Sea plate underneath Halmahera. The region is characterized by intense seismic activity at crustal, intermediate depth, and along the subducting plate. At crustal level the Halmahera seismicity along the two eastern arms of the K show strike-slip faulting style. In November 2015 a localized intense and energetic seismic activity started around Jailolo volcano in the West Halmahera Regency. The seismic sequence intermittently lasted until February 2016 and hundreds of events were felt by the population and several buildings were destroyed and damaged by the shaking. The largest shocks of the sequence have been located by global agencies (GEOFON and GCMT) showing normal faulting style. The temporal evolution of the seismicity seems to be more swarm-like type activity instead of mainshock-aftershock sequence. In spring 2016 a research project has been funded by the German's Humanitarian Aid program in collaboration with BMKG, Indonesia, with the goal of understanding the origin of the intense seismic activity and the related hazard. In summer 2016 we instrumented the area with a dense seismic network composed of 29 short period and 6 broad-band seismometers. The instruments deployment aims at characterizing the seismicity of the Jailolo region in relationship with the 2015-2016 seismic activity. The network will help to understand the seismo-tectonic of the area and the relation between seismicity and the volcanic activity at Jailolo volcano and possible link with the 2015-2016 swarm. Should the seismic activity intensify as in November 2015, we can record it and narrow down the underlying physical mechanisms. Waveform data are available from the GEOFON data centre, under network code 7G, and are embargoed until the end of 2021.
# 2
Walter, Thomas • Gaete, Ayleen • Lara, Luis • Mikulla, Stefan • Kujawa, Christian • (et. al.)
Abstract: The network consistes in 6 stations surronding the fumarole field at Lastarria volcano. These stations were operative during one month with the final purpose of detect changes in the hydrothermal system triggered by passing of seismic waves produced by artificial explosions. Waveform data are available from the GEOFON data centre, under network code 2G, and are embargoed until 001 2019.
# 3
Haberland, Christian • Seneviratne, Mahinda • Dreiling, Jennifer
Abstract: A temporary seismic network was installed in Sri Lanka for a time period of 13 months. The stations were equipped with Earth Data EDR-210 digital recorders and Trillium 120 PA, Güralp C3E and Güralp CMG-3ESP broadband sensors. Main aim of the network is to shed light on the crustal and upper mantle structure beneath the island. Also local seismic activity is studied.
# 4
Cesca, Simone • López Comino, José Ángel • Kühn, Daniela • Dahm, Torsten
Abstract: A temporary installation has been realized in the Netherlands, in the region of the Groningen gas field. The objective of this installation is to test the usage of a conventional array layout for detection of microseismicity. The region of the Groningen gas field is an excellent test ground, since the operating company NAM (Nederlandse Aardolie Maatschappij) installed a multitude of shallow borehole stations from 2014 to 2017, of which 65 – in addition to the already existing shallow borehole stations installed by KNMI (Koninklijk Nederlands Meteorologisch Instituut) – were already online during the time of measurement, thus ensuring an earthquake catalogue that is complete down to low magnitudes during the time of array installation. The site for the installation was decided together with local parties involved in the seismicity monitoring, i.e. KNMI and NAM, and was located close to the village of Wittewierum. Stations were installed from the 12th of July 2016 to the 29th of August 2016 (49 days). The array was composed of 9 stations. The array was constructed in three concentric rings of 75 m, 150 m and 225 m diameter including a central station, but the geometry had to be adapted to the local conditions. Each station consisted of a broadband sensor (Trillium 120 s), an acquisition system (CUBE datalogger), a battery, and a GPS antenna. The entire system was installed at ~1 m depth (apart from GPS and transmission antennas), requiring only the digging of shallow holes, one for the installation of a thin concrete plate and the sensor, another one for a box containing the remaining instrumentation. The array stations recorded continuously with little outages; only station WAR1 stopped recording on the 22nd of August and station WAR7 stopped recording from 20th to 22nd of August. Waveform data is available from the GEOFON data centre, under network code 1C, and is fully open.
# 5
Larose, Eric
Abstract: The experiments are performed down the Edward Bailey valley, in the Renland peninsula, Scoresby Sund, Greenland. General purpose: ambient seismic noise recordings are obtained to characterize the geometry/structure of the valley the geometry/structure of the glaciers the microseismicity of the glacier, the friction process, crack orientation and mechanisms the seismic activity of glacial rivers, the relation between hydrological flow and noise spectrum the localization and characterization of sub-glacial flow from surface recordings. Seismic stations were composed of 3C broadband Trillium compact seismometer, a Cube datalogger and a 12V (D-cell types, stacked) battery pack.The experiment splits into three surveys performed at three different sites, one after the other, from july to august 2016. In the first experiment, we deploy 11 stations, 9 of them on a flat sandy area covering, partly, immobile ice that seems to be blocked between the Bailey Glacier (upstream) and the Apusinikajik glacier (downstream). The 9 sensors are placed a few hundreds of meters from the Apusinikajik lateral front, the last 2 are placed on the glacier next to the collapsing front. In the second and third experiment (chronologically speaking), we deploy 10 and 8 stations, respectively. Each deployment is performed along a Bailey valley transect. The first one intercepts the front-end of the glacier and the sub-glacial river exit (flow of several m3/s). The second transect is performed some 850m upstream. Waveform data are available from the GEOFON data centre, under network code 3H, and are embargoed until summer of 2019.
# 6
Wigger, P. • Salazar, P. • Kummerow, J. • Bloch, W. • Asch, G. • (et. al.)
Abstract: We installed a temporary seismic network that consists of two sub-nets in order to monitor micro-seismicity at the Atacama and West Fissure Fault System in Northern Chile. The net around the West Fissure Fault System was operated during the period between November 2005 and November 2009 and again from March 2010 until March 2012. The net around the Atacama Fault System recorded from March 2010 to March 2012. Both sub-nets consist of surface stations with 3-component seismometers of type Mark L4-1Hz. The data recording is continuous at a sample rate of 200Hz, with a few time intervals recorded at only 100 Hz. Data loggers are Earth Data PR-24. Power is supplied by 60W solar panels with a 12V battery backup. The seismic monitoring system around the West Fissure Fault System covers an area of approx. 100 times 80 km at elevations between 3000m and 5000m a.s.l. and consists of an average of 11 seismic stations. The seismic monitoring system around the Atacama Fault System covers an area of approx. 40 times 30km around the Salar Grande salt lake at elevations between 600m and 1000m a.s.l. and consists of 10 surface stations. The network recorded waveforms of over 7,000 weak seismic events. These microearthquakes witness a variety of seismogenic processes such as deformation due to tectonic stress, fluid migration or metamorphic mineral reactions. They occur along major fault zones mapped at the surface, in the continental crust, at the interface between the South American and the Nazca plate and in the oceanic crust and mantle. Waveform data is available from the GEOFON data centre, under network code 8F, and is {embargoed until Jan 2022}.
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