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  • American Geophysical Union  (2)
  • Deutsches GeoForschungsZentrum GFZ  (2)
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  • 1
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    Discrimination between induced, triggered and natural earthquakes close to hydrocarbon reservoirs: A probabilistic approach based on the modeling of depletion-induced stress changes and seismological source parameters. (2015)
    American Geophysical Union
    Details
    Publication Date: 2021-06-16
    Description: Earthquakes occurring close to hydrocarbon fields under production are often under critical view of being induced or triggered. However, clear and testable rules to discriminate the different events have rarely been developed and tested. The unresolved scientific problem may lead to lengthy public disputes with unpredictable impact on the local acceptance of the exploitation and field operations. We propose a quantitative approach to discriminate induced, triggered and natural earthquakes, which is based on testable input parameters. Maxima of occurrence probabilities are compared for the cases under question, and a single probability of being triggered or induced is reported. The uncertainties of earthquake location and other input parameters are considered in terms of the integration over probability density functions (pdf). The probability that events have been human-triggered/induced is derived from the modeling of Coulomb stress changes and a rate and state dependent seismicity model. In our case a 3D boundary element method has been adapted for the nuclei of strain approach to estimate the stress changes outside the reservoir, which are related to pore pressure changes in the field formation. The predicted rate of natural earthquakes is either derived from the background seismicity or, in case of rare events, from an estimate of the tectonic stress rate. Instrumentally derived, seismological information on the event location, source mechanism and the size of the rupture plane is of advantage for the method. If the rupture plane has been estimated, the discrimination between induced or only triggered events is theoretically possible if probability functions are convolved with a rupture fault filter. We apply the approach to three recent main-shock events: (1) the Mw 4.3 Ekofisk 2001, North Sea earthquake close to the Ekofisk oil field, the 2004 Mw 4.4 Rotenburg, Northern Germany earthquake in the vicinity of the Söhlingen gas field, and the Mw 6.1 Emilia 2012, Northern Italy earthquake in the vicinity of a hydrocarbon reservoir. The three test cases cover the complete range of possible causes: clearly “human-induced”, “not even human-triggered” and a third case in-between both extremes.
    Description: Published
    Description: 2491–2509
    Description: 6T. Sismicità indotta e caratterizzazione sismica dei sistemi naturali
    Description: JCR Journal
    Description: restricted
    Keywords: Induced seismicity ; probabilistic discrimination ; hydrocarbon field ; triggered earthquake ; seismic hazard ; earthquake ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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    PAPER (OA)
  • 2
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    New insights on volcanic and tectonic structures of the southern Tyrrhenian (Italy) from marine and land seismic data (2013)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: We present results from the first crustal seismic tomography for the southern Tyrrhenian area, which includes ocean bottom seismometer (OBS) data and a bathymetry correction. This area comprises Mt. Etna, the Aeolian Islands, and many volcanic seamounts, including the Marsili Seamount. The seismicity distribution in the area depends on the complex interaction between tectonics and volcanism. The 3-D velocity model presented in this study is obtained by the inversion of P wave arrival times from crustal earthquakes. We integrate travel time data recorded by an OBS network (Tyrrhenian Deep Sea Experiment), the SN-1 seafloor observatory, and the land network. Our model shows a high correlation between the P wave anomaly distribution and seismic and volcanic structures. Two main low-velocity anomalies underlie the central Aeolian Islands and Mt. Etna. The two volumes, which are related to the well-known active volcanism, are separated and located at different depths. This finding, in agreement with structural, petrography, and GPS data from literature, confirms the independence of the two systems. The strongest negative anomaly is found below Mt. Etna at the base of the crust, and we associate it with the deep feeding system of the volcano. We infer that most of the seismicity is generated in brittle rock volumes that are affected by the action of hot fluids under high pressure due to the active volcanism in the area. Lateral changes of velocity are related to a transition from the western to the central Aeolian Islands and to the passage from continental crust to the Tyrrhenian oceanic uppermost mantle.
    Description: Published
    Description: 3703–3719
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: open
    Keywords: ocean bottom seismometers ; southern Tyrrhenian Sea ; seismic tomography ; Aeolian Islands ; Etna ; oceanic continental crust ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.06. Subduction related processes ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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    PAPER (OA)
  • 3
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    Array in Wittewierum, Netherlands (2016)
    Deutsches GeoForschungsZentrum GFZ
    Details
    Publication Date: 2022-03-28
    Description: 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.
    Language: English
    Type: info:eu-repo/semantics/workingPaper
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    GFZ OAI
  • 4
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    Grundlagen der Geophysik - Lecture Notes (2015)
    Deutsches GeoForschungsZentrum GFZ
    Details
    Publication Date: 2020-02-12
    Description: Die vorliegenden Lecture Notes wurden im Rahmen von Vorlesungen und Praktika zwischen 1999 und 2014 an den Universitäten Frankfurt, Hamburg und Potsdam entwickelt, insbesondere als Zusatzmaterial meines Moduls Einführung in die Geophysik an der Universität Hamburg. Ziel dieser Vorlesung war die breite Einführung in die Grundlagen der Geophysik, von der großskaligen, globalen Geophysik bis zur kleinskaligen oberflächennahen und angewandten Geophysik. Das Manuskript ist vom Niveau her für Anfangssemester in einem Diplom- oder Bachelor-Studiengang in der Geophysik/Ozeanographie, den Geowissenschaften oder der Physik geeignet. Die Theorie-Kapitel sind auf wenige wichtige Formeln und elementare Ableitungen beschränkt. Meßinstrumente, Meßverfahren und Anwendungen werden ausführlich besprochen und durch Beispiele vertieft. Der erste Teil beginnt mit der Entstehung der Erde und der Planeten. Der innere Aufbau der Erde und die Dynamik der Erde folgen im dritten Kapitel. Unterkapitel sind hier bereits die globale Plattentektonik, der Wärmehaushalt der Erde und die Entstehung des Erdmagnetfeldes. Im vierten Kapitel folgt das Schwerefeld der Erde und die Ansätze der angewandten Gravimetrie. Der Sto↵ des fünften Kapitels umfasst die Geomagnetik und den remanenten Gesteinsmagnetismus. In den folgenden Kapiteln wird in weitere Verfahren der angewandten Geophysik eingeführt. Die Gleichstromelektrik wird ebenso behandelt wie Verfahren, die mit elektromagnetischen Wellen arbeiten. Dabei wird auch die Arbeitsweise des Bodenradar und der Magnetotellurik beschrieben. Im vorletzten Kapitel wird in seismische Verfahren eingeführt, die in der angewandten Geophysik eine wichtige Rolle spielen. Hierbei werden nötige Grundlagen der Theorie elastischer Wellen ebenso wie praktische Aspekte der geometrischen Ausbreitung von Raumwellen durch die Erde kurz beschrieben. Das letzte Kapitel ist den Erdbeben und der Seismologie gewidmet. Begleitende Übungsaufgaben sind auf Anfrage erhältlich.
    Language: German
    Type: info:eu-repo/semantics/book
    Format: application/pdf
    Format: application/pdf
    Format: application/pdf
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    GFZ OAI
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