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SUMMARY We provide new results from a controlled-source seismic experiment on the deepest part of the Val Sesia crust–mantle section of the Ivrea–Verbano zone (IVZ) in the Italian Alps. The IVZ is a tilted, almost complete section through the continental crust and exposes gabbros and peridotites in the structurally deepest level, coinciding with high-resolution gravity anomalies imaging the Ivrea geophysical body. The seismic experiment SEIZE (SEismic imaging of the Ivrea ZonE) was conducted along two crossing profiles: an NNE-SSW profile of ∼11 km length and an E-W profile of ∼16 km length. 432 vibration points were recorded with 110 receivers resulting in 24 392 traveltime picks. Inversion methods using Markov chain Monte Carlo techniques have been used to derive an isotropic 3-D P-wave velocity model based on first break traveltimes (refracted phases) from controlled source seismic data. Resulting seismic P-wave velocities (Vp ) range from 4.5 to 7.5 km s−1, with an expected general trend of increasing velocities with depth. A sharp velocity change from low Vp in the West to high Vp in the East marks the Insubric Zone (ISZ), the Europe–Adria plate boundary. The most prominent feature of the 3-D tomography model is a high-velocity body (Vp increases from 6 to 7.5 km s−1) that broadens downwards. Its pointy shape peaks the surface East of Balmuccia at a location coincident with the exposed Balmuccia peridotite. Considering rock physics, high-resolution gravity and other geophysical data, we interpret this high-velocity body as dominantly composed of peridotite. The dimension of this seismically imaged peridotite material is far bigger than interpreted from geological cross-sections and requires a revision of previous models. The interpretation of ultramafic bodies in the IVZ as fragments of mantle peridotites interfingered in the crust during pre-Permian accretion is not supported by the new data. Instead, we revive a model that the contact between the Balmuccia peridotite and the Permian mafic magmas might represent a fossil continental crust–mantle transition zone.

The 1989 Mw 6.9 Loma Prieta earthquake is the first major event to occur along the San Andreas fault (SAF) zone in central California since the 1906 M 7.9 San Francisco earthquake. Given the complexity of this event, uncertainty has persisted as to whether this earthquake ruptured the SAF itself or a secondary fault. Recent work on the SAF in the Coachella Valley in southern California has revealed similar complexity, arising from a nonplanar, nonvertical fault geometry, and has led us to reexamine the Loma Prieta event. We have compiled data sets and data analyses in the vicinity of the Loma Prieta earthquake, including the 3D seismic velocity model and aftershock relocations of Lin and Thurber (2012), potential field data collected by the U.S. Geological Survey following the earthquake, and seismic refraction and reflection data from the 1991 profile of Catchings et al. (2004). The velocity model and aftershock relocations of Lin and Thurber (2012) reveal a geometry for the SAF that appears similar to that in the Coachella Valley (although rotated 180°): at Loma Prieta the fault dips steeply near the surface and curves with depth to join the moderately southwest-dipping main rupture below 6 km depth, itself also nonplanar. The SAF is a clear velocity boundary, with higher velocities on the northeast, attributable to Mesozoic accretionary and other rocks, and lower velocities on the southwest, attributable to Cenozoic sedimentary and volcanic rocks of the La Honda block. Rocks of the La Honda block have been offset right-laterally hundreds of kilometers from similar rocks in the southern San Joaquin Valley and vicinity, providing evidence that the curved northeast fault boundary of this block is the plate boundary. Thus, we interpret that the Loma Prieta earthquake occurred on the SAF and not on a secondary fault.

The underground of the northern German lowlands, located in the Central European Basin System (CEBS), is characterized by numerous Permian Zechstein salt structures, which are found at depths of up to more than 2000m. The lowlands were transgressed several times by the Scandinavian Ice Sheet during the Pleistocene glacial cycles. Several researchers have noted that there seems to be a spatial correlation between the positions of Weichselian end moraines in Northern Germany and subsurface salt structures. Thus, it was assumed that the pressure of the advancing ice sheet triggers salt tectonic movements, which in return influences the spatial configuration of the ice extent.Using high resolution laser scan digital elevation models, we have recently mapped more than 150 linear negative landforms (up to several km in length, up to 20 m in depth and up to more than 100 m in width) in northern Germany that we term “surface cracks” and which we interpret as surface expansion ruptures caused by ice sheet induced salt movements related to the last glacial cycle (Weichselian glaciation). This interpretation is based on: (1) geomorphological analyses, which also allow for a relative geochronological classification; (2) a reassessment of existing theoretical models on ice sheet induced salt movement, and; (3) new physical modeling experiments. Our results shed a new light on the geomorphology of the northern German young morainic landscapes, illustrating an active interplay between climate (glaciations) and loading-induced subsurface motions (buried salt structures).

We apply a transdimensional, hierarchical Markov chain Monte Carlo sampling algorithm (McMC) for 2-D cross-hole travel-time tomography in transversely isotropic media with vertical symmetry axis. The McMC approach has several advantages compared to classical inversion approaches: It is a global search, the high number of tested models allows the statistical analysis including the calculation of a reference model as well as uncertainty estimation, no initial models or regularization parameters are needed, the amount of data noise is automatically determined, and the model parametrization is data dependent and self-adjusting. For the forward solution a FD Fast Marching method utilizing second-order Godunov schemes is used. The performance of the approach is first tested on synthetic datasets to evaluate the potential and possible limitation to recover anisotropic models. We have shown that the recovery of models described by 2 anisotropic parameters (Thomsen parameters) and the vertical velocity is possible for observation scenarios with good distribution of sources and receivers. For more realistic observational geometries (i.e. cross-hole experiments), the recovery of the 3 parameters is limited, but still possible for example for the elliptical anisotropic case (ε = δ) or regarding the horizontal velocity. Finally we applied the McMC approach to a well-studied real cross-hole data set from the MALLIK 2002 research program and compared the results with previous conventional inversions.

The application of distributed acoustic sensing in borehole measurements allows for the use of fibre optic cables to measure strain. This is more efficient in terms of time and costs compared with the deploying of conventional borehole seismometers. Nevertheless, one known drawback for temporary deployment is represented by the freely hanging wireline cable slapping and ringing inside the casing, which introduces additional coherent coupling noise to the data. The present study proposes an explanation for the mechanism of noise generation and draws an analogy with similar wave propagation processes and phenomena, such as ghost waves in marine seismics. This observation allows to derive a ringing noise filter function, to study its behaviour and to consider known effects of the gauge length filter. After examining existing methods aimed at eliminating ringing noise and results of their application, we propose a two‐step approach: (1) developing a denoising method based on a matching pursuit decomposition with Gabor atoms and (2) subtracting the noise model for imaging improvement. The matching pursuit method focuses on decomposing the original input signal into a weighted sum of Gabor functions. Analysing Gabor atoms properties for frequency, amplitude and position in time provides the opportunity to distinguish parts of the original signal denoting noise caused by the vibrating cable. The matching pursuit decomposition applied to the distributed acoustic sensing‐vertical seismic profiling data at the geothermal test site Groß Schönebeck provides a versatile processing instrument for noise suppression., German Federal Ministry of Economic Affairs and Energy

The Groß Schönebeck site in the North German Basin serves as research platform for studying the geothermal potential of deeply buried Permian reservoir rocks and the technical feasibility to extract their geothermal heat. The structural setting of the site was investigated in more detail by studying a newly acquired 3D-seismic survey to improve the structural picture that was based on several old 2D seismic lines so far. The new data allows a revision of the geological interpretation of the site, enabling the set-up of a new reservoir model and providing base information for a possible further site development of the Permian and Permo-Carboniferous targets. The 3D seismic of Groß Schönebeck allows for the first time a consistent geological interpretation and model parameterization of the well-studied geothermal site. Main reflector horizons and the corresponding stratigraphic units were mapped and the structural pattern of the subsurface presented in the 8 km x 8 km x 4 km large seismic volume. While some fracture and fault patterns are visible in the upper Zechstein and post-Permian units, formerly hypothesized large offset faults are not present in the Rotliegend reservoir itself. However, a well-established graben-like structure at the top of the Zechstein succession is most likely related to broken anhydritic Zechstein stringers. Most reflectors above the salt show a rather undisturbed pattern. The main reservoir sandstone of the Dethlingen Formation (Rotliegend) was mapped and characterized. The base of the underlying Permo-Carboniferous volcanic rock sequence and hence its thickness could not be depicted reliably from the geophysical data. Based on the new seismic data and the available reconnaissance drilling, logging, and laboratory data of the Groß Schönebeck research site, the thickness and distribution of the sedimentary Rotliegend (with emphasis of the sandy reservoir section) and of the volcanic rock sequence was modelled and parameterized with petrophysical properties (i.e., total and effective porosity, fluid permeability, bulk density, thermal conductivity, thermal diffusivity, and specific heat capacity), providing a more realistic reservoir description. The data and interpretation constitute the basis for a better understanding of the dominating processes at the site and for future measures. Further site development could include a deepening of one well to give evidence on the volcanic rock sequence and consider deviated wells into favourable zones and the design of a fracture-dominated utilization approach.

In Deutschland leiden schatzungsweise 1-2% der Bevolkerung unter einer chronischen Wunde. Hierbei gilt es nicht nur an die haufigen Entitaten, sondern auch an seltenere ulzerierende Erkrankungen zu denken. Ein grundlegendes Verstandnis der Pathophysiologie bezuglich der Wundentstehung und Wundheilung hilft den Wundzustand richtig einschatzen zu konnen, um erforderliche diagnostische Schritte und eine phasengerechte Therapie einzuleiten. Die ABCDE-Regel stellt hierbei einen praktischen Leitfaden fur die Wunddiagnostik dar. Bei der klinischen Untersuchung interpretiert der Wundtherapeut entsprechend des Wunddreiecks den Wundgrund, den Wundrand und die Wundumgebung. Dieser Ansatz kann praktische therapeutische Entscheidungen, z.B. die Wahl der Wundauflage, vereinfachen. Nicht immer ist ein kausaler Therapieansatz moglich oder ausreichend. Vielmehr muss auf begleitende Faktoren geachtet und ein ganzheitliches und interdisziplinares Konzept erarbeitet werden. Hierbei kommt dem Hausarzt eine zentrale Schlusselrolle zu.

The Ivrea-Verbano Zone (IVZ) located in the Italian Alps is known as one of most complete archetypes of continental crust–upper mantle section on Earth (e.g. Pistone et al., 2017). Because of its accessibility at the surface it can be used as natural laboratory to improve the understanding of the crust–mantle transition zone. Several geophysical observables indicate the presence of mantle rocks (high density, high seismic velocity) in the shallow sub-surface (~ 1 km), commonly known as the “Bird’s Head” or Ivrea body (Berckhemer, 1968; Diehl et al., 2009; Scarponi et al., 2021). The project SEIZE images and characterizes the shallow upper crust at the Balmuccia site (Italy) providing depth, extent and shape of the outcropping Ivrea body as well as its rock properties. Our tomographic study covers the crust down to about 3 km depth, while seismic reflection imaging is possible down to 6 km depth or deeper. With SEIZE we contribute to the comprehensive ICDP Drilling program in the Ivrea-Verbano ZonE (DIVE, www.dive2ivrea.org).To tackle this task, a controlled source (vibroseis) seismic experiment was carried out in the region around Balmuccia in October 2020. The seismic survey comprised two crossing profiles with a total length of 28 km which ran along (NNE-SSW) and across (W-E) the Balmuccia peridotite. In total, 432 vibro points were acquired with a nominal distance of ~60 m which were recorded using a fix-spread (110 receivers, ~250 m spacing) and a roll-along setup (330 receivers, ~20 m spacing).To obtain a structural image of the shallow upper crust various seismic techniques are applied: The fix-spread data set is used to recover the velocity structure down to 3 km depth. By using a 3D Markov chain Monte Carlo travel time tomography a shallow, distinct high velocity body is imaged in 3D near Balmuccia, at the proposed drill site. Reflection seismic processing is applied to the roll-along data set. However, the difficult terrain setting (deep mountain valleys) results in complex wave propagation that is challenging for conventional processing methods (e.g. static and dynamic corrections, CDP stacking). Therefore, pre-stack migration techniques are applied enabling the imaging of steeply dipping structures.

Subsurface imaging of the critical zone, where are regolith is produced from bedrock, plays a significant role in understanding the geological and biological interaction at depths. The depth where we can find the intact bedrock is also often referred to as the weathering front. In the scheme of the EarthShape project, we assess one of the hypotheses which link the advance of weathering front to different climate conditions. We present the seismic investigation result from Santa Gracia National Reserve, Chile, one of the main EarthShape sites, which is in a transitional area between the arid to the semi-arid climatic zone. We investigate the weathering profile of this area by acquiring a 500 m long near-surface seismic profile using weight drop sources and 3-component geophones. With the acquired data, we perform two different seismic imaging methods: 1) Body wave tomography, and 2) Multichannel Analysis of Surface Wave (MASW) with Bayesian inversion. Both methods allow us to image the P- and S-wave velocity of the subsurface down to 80 and 60 meters depth, respectively. In addition to the absolute velocity models, we also produce the vertical velocity gradient model, which also provides us with extra tools in interpreting the weathering structure. The resulting models were then validated by existing borehole data located in the middle of the profile. Using the 87 meters deep borehole information, we identified three major layers in the weathering profiles: saprolite, weathered bedrock, and bedrock. The layers were identified by the different seismic velocities, which represent different stages of weathering in the subsurface. Across the profile, the identified weathering front can be traced down to 30 meters depth and is relatively parallel to the surface topography. The interpreted weathering layers also correlate with existing geochemical analysis of the borehole coring and even another perspective in the multi-disciplinary interpretation of the weathering zone. Accordingly, seismic imaging of the critical zone using different methods allows us to improve the critical zone interpretation, either as a combined or independent approach in regions without borehole data available.

Loading and unloading effects of the Scandinavian Ice Sheet triggered halotectonic movements in Northern Germany. We present newly detected geomorphological features���termed surface cracks���which indicate a relation between ice sheet-induced salt movement and surface processes. As a part of the Central European Basin System, numerous Zechstein salt structures are abundant in the North German Basin. On the basis of high-resolution digital terrain data, more than 160 surface cracks were mapped in Northern Germany, which were grouped into 30 clusters. Almost all of the surface cracks occur above the top regions of Zechstein salt structures. The surface cracks can be several kilometres long, up to more than 20 m deep and more than 100 m wide. The comparison of the shape of the salt structures and the orientation of the cracks reveals a geometric dependency, indicating that the cracks preferably occur near the crest margins of the salt structures. Furthermore, 3D seismic data from two sites show that subsurface faults originating from salt movement exist beneath the surface cracks. We interpret the cracks as surface ruptures due to ice sheet-induced halotectonic movements. The cracks occur in a variety of Quaternary sediments and landforms. This indicates that widespread halokinetic movements occurred in the region after the last (Weichselian) deglaciation and likely before the thawing of the permafrost, possibly in a time frame from c. 30���20 ka until c. 15 ka.

The ongoing preference for dark colours in parquet and furniture is a driving force for colour modification of bright wood species. The treatment of oak wood with gaseous ammonia (fuming) leads to dark colours, but residual ammonia in the wood may lead to bonding failures with resins, odour nuisance and thus customer complaints. The focus of the present paper is the determination and emission of remaining ammonia in fumed oak. A fast and convenient approach based on Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy was developed to replace the currently applied time-consuming and complex determination procedures. The integrated area of the infrared (IR) region between 1575 and 1535 cm−1 shows a relationship with the coefficient of determination (R2=0.76) to the residual ammonia content determined by the micro-chamber/thermal extractor (μCTE) method. The prediction accuracy was further improved by partial least square regression calculations. Promising models with high R2 (0.85), low root mean square error of cross-validation (RMSE-CV=1.08%) with five principal components were established and already integrated successfully into the production as input control. FTIR-ATR spectroscopy proved to be a simple and fast predictive method to estimate residual ammonia in fumed oak.

We present a new workflow for the localization of seismic events which is based on a diffraction stacking approach. In order to address the effects from complex source radiation patterns, we suggest to compute diffraction stacking from a characteristic function (CF) instead of stacking the original waveform data. A new CF, which is called in the following mAIC (modified from Akaike Information Criterion) is proposed. We demonstrate that both P- and S-wave onsets can be detected accurately. To avoid cross-talk between P and S waves due to inaccurate velocity models, we separate the P and S waves from the mAIC function by making use of polarization attributes. Then, the final image function is represented by the largest eigenvalue as a result of the covariance analysis between P-and S-image functions. Results from synthetic experiments show that the proposed diffraction stacking provides reliable results. The workflow of the diffraction stacking method was finally applied to local earthquake data from Sumatra, Indonesia. Recordings from a temporary network of 42 stations deployed for nine months around the Tarutung pull-apart basin were analysed. The seismic event locations resulting from the diffraction stacking method align along a segment of the Sumatran Fault. A more complex distribution of seismicity is imaged within and around the Tarutung basin. Two lineaments striking N-S were found in the centre of the Tarutung basin which support independent results from structural geology.

Intelligent packaging is an emerging technology, aiming to improve the standard communication function of packaging. Radio frequency identification (RFID) assisted smart packaging is of high interest, but the uptake is limited as the market needs cost-efficient and sustainable applications. The integration of screen printed antennas and RFID chips as smart labels in reusable cardboard packaging could offer a solution. Although paper is an interesting and recyclable material, printing on this substrate is challenging as the ink conductivity is highly influenced by the paper properties. In this study, the best paper/functional silver ink combinations were first selected out of 76 paper substrates based on the paper surface roughness, air permeance, sheet resistance and SEM characterization. Next, a flexible high frequency RFID chip (13.56 MHz) was connected on top of screen printed antennas with a conductive adhesive. Functional RFID labels were integrated in cardboard packaging and its potential application as reusable smart box for third party logistics was tested. In parallel, a web-based software application mimicking its functional abilities in the logistic cycle was developed. This multidisciplinary approach to developing an easy-scalable screen printed antenna and RFID-assisted smart packaging application is a good example for future implementation of hybrid electronics in sustainable smart packaging. ispartof: MATERIALS vol:14 issue:19 ispartof: location:Switzerland status: published

Understanding geochemical processes is an important part of geothermal exploration to get information about the source and evolution of geothermal fluids. However, in most cases knowledge of fluid properties is based on few parameters determined in samples from the shallow subsurface. This study presents a new approach that allows to conclude from the combination of a variety of these data on processes occurring at depth in a geothermal reservoir. The neural network clustering technique called “self-organizing maps” (SOMs) successfully distinguished two different geothermal settings based on a hydrochemical database and disclosed the source, evolution and flow pathways of geothermal fluids. Scatter plots, as shown in this study, are appropriate presentations of element concentrations and the chemical interaction of water and rock at depth. One geological setting presented here is marked by fault dominated fluid pathways and minor influence of volcanic affected fluids with high concentrations of HCO3, Ca and Sr. The second is a magmatically dominated setting showing strong alteration features in volcanic rocks and accommodates acidic fluids with high SO4 and Si concentrations. Former studies, i.e., Giggenbach (1988), suggested Cl, HCO3 and SO4 to be generally the most important elements for understanding hydrochemical processes in geothermal reservoirs. Their relation has been widely used to classify different water types in geothermal fields. However, this study showed that non-standard elements are at least of same importance to reveal different fluid types in geothermal systems. Therefore, this study is an extended water classification approach using SOM for element correlations. SOM have been proven to be a successful method for analyzing even relatively small hydrochemical datasets in geothermal applications.

At the geothermal test site near Groß Schönebeck (NE German Basin), a new 3D seismic reflection survey was conducted to study geothermal target layers at around 4 km depth and 150°C. We present a workflow for seismic facies classification and modelling which is applied to a prospective sandstone horizon within the Rotliegend formation. Signal attributes are calculated along the horizon using the continuous Morlet wavelet transform. We use a short mother wavelet to allow for the temporal resolution of the relatively short reflection signals to be analysed. Time‐frequency domain data patterns form the input of a neural network clustering using self‐organizing maps. Neural model patterns are adopted during iterative learning to simulate the information inherent in the input data. After training we determine a gradient function across the self‐organizing maps and apply an image processing technique called watershed segmentation. The result is a pattern clustering based on similarities in wavelet transform characteristics. Three different types of wavelet transform patterns were found for the sandstone horizon. We apply seismic waveform modelling to improve the understanding of the classification results. The modelling tests indicate that thickness variations have a much stronger influence on the wavelet transform response of the sandstone horizon compared with reasonable variations of seismic attenuation. In our interpretation, the assumed thickness variations could be a result of variable paleo‐topography during deposition of predominantly fluvial sediments. A distinct seismic facies distribution is interpreted as a system of thicker paleo‐channels deposited within a deepened landscape. The results provide constraints for the ongoing development of the geothermal test site., Federal Ministry for Economic Affairs and Energy http://dx.doi.org/10.13039/501100006360

The Klaipeda Geothermal Demonstration Plant (KGDP), Lithuania, exploits a hypersaline sodium-chloride (salinity c. 90 g/L) groundwater from a 1100 m deep Devonian sandstone/siltstone reservoir. The hydrogen and oxygen stable isotope composition is relatively undepleted (δ18O=c. -4.5‰), while the δ34S is relatively “heavy” at +18.9‰. Hydrochemical and isotopic data support the existing hypothesis that the groundwater is dominated by a hypersaline brine derived from evapoconcentrated seawater, modified by water-rock interaction and admixed with smaller quantities of more recent glacial meltwater and/or interglacial recharge. The injectivity of the two injection boreholes has declined dramatically during the operational lifetime of the KGDP. Initially, precipitation of crystalline gypsum led to a program of rehabilitation and the introduction of sodium polyphosphonate dosing of the abstracted brine, which has prevented visible gypsum precipitation but has failed to halt the injectivity decline. While physical or bacteriological causes of clogging are plausible, evidence suggests that chemical causes cannot be excluded. Gypsum and barite precipitation could still occur in the formation, as could clogging with iron/manganese oxyhydroxides. One can also speculate that inhibitor dosing could cause clogging of pore throats with needles of calcium polyphosphonate precipitate.

We analyzed the noise recordings of a short-period seismic network to derive a shallow crustal S-wave velocity model at the Sumatra Fault in Northern Sumatra, Indonesia. By correlating the noise of 40 seismic stations' recording for 9 months, we could recover Rayleigh waves from vertical component recordings with sufficient signal-to-noise ratio. Group velocities of the Rayleigh waves could be determined in the period range from 0.71 to 4.4 s. These group velocities were used to invert for 2D group velocity maps at specific periods. Finally, the derived group velocity maps were inverted for a 3D S-wave velocity model. This model shows a region of a strong velocity decrease off the Great Sumatran Fault Zone, at the northeastern margin of the young Tarutung pull-apart basin. This observed low velocity block coincides with a caldera-like morphological feature which is interpreted as the surface expression of a hidden volcanic caldera. Considering the surface manifestations of geothermal activity around this anomaly, we conclude that the caldera is still acting as a heat source. On the other hand, the weak morphological expression at the surface indicates a certain age of the caldera which might be older than the Tarutung pull-apart basin. The findings provide important constraints on general concepts for the formation of pull-apart basins along the Sumatran fault and their relation to volcanism.

For the first time a dense seismic network (AcehSeis) consisting of 30 short-period seismic stations was installed for 10 months from July 2014 in order to record crustal earthquakes in Central Aceh, Northern Sumatra, following the hazardous earthquake with magnitude Mw. 6.1, July 2nd, 2013. The objective of this research is to investigate the active fault characteristics derived from local earthquake data combined with a digital elevation model. The network recorded more than 1790 local events occurring along the main Great Sumatran Fault (GSF) and its secondary faults. Local earthquakes with azimuthal gap angles greater than 180° were excluded to avoid non-unique earthquake locations. Therefore from all recorded earthquakes, 1127 local earthquakes were used for further seismological analysis. A method of simultaneous earthquake relocation and 1D velocity determination was applied to obtain better location of earthquakes. The output of the first relocated seismicity was then relocated again by using a double difference relocation method. After relocation, earthquakes are concentrated in a narrow zone along the active fault, indicating the reliability of the earthquake location. We then determined the focal mechanism of earthquakes, based on the first polarity picks. The seismicity distribution correlates with the well-known GSF and its main secondary faults. Earthquake locations also clearly revealed several active segments which include the Batee, Beutong, Tangse-Geumpang, Lampahan, Aceh and Seulimeum, and Nisam faults. Also less-known faults as the Pamue and Atu Lintang-Peusangan faults are imaged. In Northern Aceh an unknown earthquake cluster associated with an active fault, the Nisam Fault was detected, which is also visible in the topography. The seismicity along GSF is offset at around 96.7 E, constrained by the nearly N-S striking Atu Lintang-Peusangan Fault confirming the segmentation of GSF at this longitude. The Aceh segment and the Seulimum Fault in the northernmost region of the network are both active and clearly imaged by the seismicity. The Pamue and the Lampahan Faults seem to be the splay of GSF as indicated by identical strike direction as the GSF. The Lampahan fault is characterized by NW-SE seismicity lineation, which is in agreement with the focal mechanisms. The Laut Tawar Lake could be a part of the Lampahan Fault that is also offset at ∼96.7 E at the line of the Atu Lintang-Peusangan fault. The Burni Geureudong Fault on the other hand strikes ENE-WSW which suggests a conjugate fault of the Lampahan Fault.

The North German Basin is one of the three major type localities in Germany for deep geothermal energy. Here, the pore space is the dominant parameter, in contrast to fractures (Rhine Graben) and karst (Molasse Basin). To further develop the geothermal research platform Groß Schönebeck located in the Northeast German Basin, a subset of the North German Basin, we investigated the geological structure and the existence of possible fault systems in the subsurface. For this purpose, we carried out a high-resolution 3-D reflection seismic survey at the location to overcome methodical restrictions of the few 2-D seismic profiles that cross the area of interest, such as spatial focusing effects and fault imaging. The survey area extends 8 km × 8 km at the surface and focusses down to reservoir depths at 4 km. With four vibrators as source (12–96 Hz sweep, 12 s duration), we used a source line spacing of 700 m and a receiver line spacing of 400 m with both 50 m source and geophone spacing. Data processing encompassed CRS (Common Reflection Surface) stacking, post-stack time migration and depth conversion. We observed a smooth doming of the Zechstein salt from 0.6 to 1 km thickness above the continuous top of the Rotliegend Group at around 4 km depth, and the Mesozoic horizons above appear as mainly continuous reflection surfaces with gentle undulations and occasional normal faulting. We highly resolved the supra-salt sequences in the study area for the first time, which allowed us image an almost complete suite of reflectors mapped in other parts of the Northeast German Basin. However, less resolved, lower frequency images are encountered deeper than ~ 4 km. Two important factors for further field development are that we do not observe an apparent influence of crustal-scale faults, which were expected from former conceptual models for the region, and that at the current status of work, the reservoir does not show a fracture-dominated character.

The Campanian-Maastrichtian formation was studied and defined in a Pelagian basin, mainly, in the Sidi El Kilani oil field. The carbonates of the Abiod formation are considered as a potential reservoir for several years. The present study aims to characterize the lateral variation in thickness and lithology of the Abiod reservoir based on borehole lithology logs and electrical well logging. This chalky carbonate shows a relevant porosity and permeability variance. Furthermore, the subsurface data have allowed recognizing the internal architecture of Pelagian Basin which is a stable domain, but also a rather a complex structural domain. The sedimentary facies of the Abiod formation (Campanian-Maastrichtian) have been guided by the existence of deep faults and older structures which evolved into major E-W and N-S faults and characterize the geodynamic structures and tectonic framework. The structural framework based on the major structures controls the existence of the deep reservoir and its distribution in the basin. Throughout the reservoir of the Abiod formation, areas are widespread where there is relevant thickness and relevant porosity, particularly along the major faults corridors and in the summit parts of the main anticlines.

The San Andreas fault (SAF) is one of the most studied strike‐slip faults in the world; yet its subsurface geometry is still uncertain in most locations. The Salton Seismic Imaging Project (SSIP) was undertaken to image the structure surrounding the SAF and also its subsurface geometry. We present SSIP studies at two locations in the Coachella Valley of the northern Salton trough. On our line 4, a fault‐crossing profile just north of the Salton Sea, sedimentary basin depth reaches 4 km southwest of the SAF. On our line 6, a fault‐crossing profile at the north end of the Coachella Valley, sedimentary basin depth is ∼2–3 km and centered on the central, most active trace of the SAF. Subsurface geometry of the SAF and nearby faults along these two lines is determined using a new method of seismic‐reflection imaging, combined with potential‐field studies and earthquakes. Below a 6–9 km depth range, the SAF dips ∼50°–60° NE, and above this depth range it dips more steeply. Nearby faults are also imaged in the upper 10 km, many of which dip steeply and project to mapped surface fault traces. These secondary faults may join the SAF at depths below about 10 km to form a flower‐like structure. In Appendix D, we show that rupture on a northeast‐dipping SAF, using a single plane that approximates the two dips seen in our study, produces shaking that differs from shaking calculated for the Great California ShakeOut, for which the southern SAF was modeled as vertical in most places: shorter‐period (T

Within a seismic reflection processing work flow, the common-reflection-surface (CRS) stack can be applied as an alternative for the conventional normal moveout (NMO) or the dip moveout (DMO) stack. The advantages of the CRS stack include (1) data-driven automatic determination of stacking operator parameters, (2) imaging of arbitrarily curved geological boundaries, and (3) significant increase in signal-to-noise (S/N) ratio by stacking far more traces than used in a conventional stack. In this paper we applied both NMO and CRS stackings to process a sparse 3D seismic data set acquired within a geothermal exploration study in the Polish Basin. The stacked images show clear enhancements in quality achieved by the CRS stack in comparison with the conventional stack. While this was expected from previous studies, we also found remarkable improvements in the quality of seismic attributes when the CRS stack was applied instead of the conventional stack. For the major geothermal target reservoir (Lower Jurassic horizon Ja1), we present a comparison between both stacking methods for a number of common attributes, including root–mean–square (RMS) amplitudes, instantaneous frequencies, coherency, and spectral decomposition attributes derived from the continuous wavelet transform. The attribute maps appear noisy and highly fluctuating after the conventional stack, and are clearly structured after the CRS stack. A seismic facies analysis was finally carried out for the Ja1 horizon using the attributes derived from the CRS stack by using self-organizing map clustering techniques. A corridor parallel to a fault system was identified, which is characterized by decreased RMS amplitudes and decreased instantaneous frequencies. In our interpretation, this region represents a fractured, fluid-bearing compartment within the sandstone reservoir, which indicates favorable conditions for geothermal exploitation.

A passive seismic experiment with 42 short-period stations was setup for 10 months from May 2011 within a 20–30 km radius covering the Tarutung basin and the northern part of the Sarulla graben along the seismically active Sumatran fault (North Sumatra, Indonesia). The objective of the project is to investigate the geothermal setting based on the Vp and Vp/Vs structures and the distribution of seismicity. We recorded 2856 local earthquakes by at least 8 stations which were reduced to 809 events having gap angle less than 180°. The initial earthquake locations were determined using simultaneous inversion for hypocenters and 1D velocity structure followed by 3D tomographic inversion. The resulting seismicity distribution, Vp and Vp/Vs structure reveal systematic differences between the Tarutung basin and the Sarulla graben. The Tarutung pull-apart basin is characterized by a complex structure reflected by a broader distribution of seismicity compared with the very narrow, rather vertical hypocenter distribution in the Sarulla graben, which was formed by fault-perpendicular extension and not by pull-apart tectonics. High Vp/Vs values near to the surface are imaged within the Sarulla graben and northeast of the Tarutung basin. These features are interpreted as fluid bearing sediments with fracturing indicating potentially favorable conditions for geothermal exploitation. The localized fluid flow northeast of Tarutung could be explained by the releasing step-over structure of the pull-apart basin and resulting dilatational stress regime in this part of the basin. Heat sources are assumed to be located at greater depth in association with magmatic activities accompanying the subduction process, and the heat is transported along the Sumatran fault to shallow depth.

We present a three-dimensional (3-D) P-wave attenuation (Qp) model for the geodynamically active swarm earthquake area of West Bohemia/Vogtland in the Czech/German border region. Path-averaged attenuation t* is calculated from amplitude spectra of time windows around the P-wave arrivals of local earthquakes. Average t/t* value or Qp for stations close to Nový Kostel are very low (

In 2010, project CoCoCo (incipient COntinent-COntinent COllision) recorded a 650 km long amphibian N-S wide-angle seismic profile, extending from the Anatolian plateau across southern Turkey and Cyprus to just south of the Eratosthenes Seamount (ESM). The aim of the project is to reveal the impact of the transition from subduction to continent-continent collision of Africa with Anatolia. Arrival picking, finite-differences ray-tracing and inversion of the offshore and on-offshore data produced a tomographic model across southern Cyprus, the accretionary wedge and the ESM. The main features of this model are (1) crustal P-velocities predominantly lower than 6.5 km/s beneath the ESM, (2) crustal thickness between 28 and 37 km, (3) an upper crustal reflection at 5 km depth beneath the ESM, (4) the likely presence of oceanic crust south of the ESM and a transform margin north of it and (5) a 12 km thick ophiolite sequence on Cyprus. Land shots on Turkey, also recorded on Cyprus, gravity data and geological and previous seismic investigations allow to derive a layered velocity model beneath Anatolia and the northern part of Cyprus. The main features of this model are (1) Moho depths of 38–45 km beneath the Anatolian plateau, (2) an upper and lower crust with large lateral changes in velocity and thickness, (3) a north-dipping subducting plate below Cyprus with a steepening of the dip-angle of the plate at about 45 km depth. Thus, the wide-angle seismic and gravity data provide detailed insights into the 2-D geometry and velocity structures associated with the Cyprus Arc collision zone. Finally, integrated analysis of the geophysics and geology allows a comprehensive interpretation of the crustal structure related to the collision process.

Near‐vertical faults can be imaged using reflected refractions identified in controlled‐source seismic data. Often theses phases are observed on a few neighboring shot or receiver gathers, resulting in a low‐fold data set. Imaging can be carried out with Kirchhoff prestack depth migration in which migration noise is suppressed by constructive stacking of large amounts of multifold data. Fresnel volume migration can be used for low‐fold data without severe migration noise, as the smearing along isochrones is limited to the first Fresnel zone around the reflection point. We developed a modified Fresnel volume migration technique to enhance imaging of steep faults and to suppress noise and undesired coherent phases. The modifications include target‐oriented filters to separate reflected refractions from steep‐dipping faults and reflections with hyperbolic moveout. Undesired phases like multiple reflections, mode conversions, direct P and S waves, and surface waves are suppressed by these filters. As an alternative approach, we developed a new prestack line‐drawing migration method, which can be considered as a proxy to an infinite frequency approximation of the Fresnel volume migration. The line‐drawing migration is not considering waveform information but requires significantly shorter computational time. Target‐oriented filters were extended by dip filters in the line‐drawing migration method. The migration methods were tested with synthetic data and applied to real data from the Waltham Canyon fault, California. The two techniques are applied best in combination, to design filters and to generate complementary images of steep faults.

Black shales are organic-rich rocks with the potential to contain oil or gas. On the Danish island Bornholm, Lower Palaeozoic black shales at shallow depth ([Formula: see text]) have a high maturity and a high total organic carbon content. We carried out seismic measurements in the southern part of Bornholm in October 2010 along two profiles to study the seismic properties of the shallow-lying black shales. The profiles were located as near as possible to existing borehole locations for geologic control, and were arranged perpendicular to each other to allow an estimate of the 3D structure of the subsurface. We analyzed the data using P-wave traveltime tomography and obtained 2D P-wave velocity models with a good resolution up to a depth of 100 m. Based on borehole information and the geologic setting, three formations can be identified in the tomography models: (a) the Komstad Limestone Formation with a thickness of about 4 m, (b) the Alum Shale Formation with a total thickness of 33 m, and (c) the Læså Formation consisting of sandstones. The Alum Shale appears as a low velocity zone between the Komstad Limestone at the top and the Læså Sandstone Formation beneath. All layers dip southwestward. We observed good agreements between borehole-logging data, acoustic velocity measurements of Alum Shale samples in the laboratory, and our P-wave velocity tomograms.

SUMMARY A seismic reflection/refraction survey across the San Andreas fault near Parkfield, California, has refined our knowledge of the upper crustal structure of the central California Coast Ranges at the San Andreas Fault Observatory at Depth (SAFOD). The survey consisted of a 46-km-long line of seismographs (25–50 m spacing) and 63 explosions (25–200 kg; nominal spacing of 500 m, with some gaps). The traveltimes of refracted P and S waves from the explosions constitute independent data sets of relatively high quality that were inverted to produce P- and S-wave velocity models (Vp, Vs) along the profile, extending to as much as 5 km depth. The Vp and Vs models show a prominent lateral drop in velocities a few hundred metres northeast of SAFOD, between the drill hole and the San Andreas fault. The Vp model shows particularly well a southwest-dipping velocity inversion beneath SAFOD, the top of which correlates with a fault penetrated by the drill hole that separates granitic rocks above from sedimentary rocks below. In addition to Vp and Vs models, a Vp/Vs model was derived. A Vp/Vs ratio lower than 1.73 is seen only at depth, in a narrow zone beginning at the target earthquakes for SAFOD and extending downward and northeastward into the North America Plate. Clusters in the parameter space spanned by Vp/Vs ratios and Vp can be identified by two different methods, one more intuitive analytical method and one more abstract method based on neural network techniques. These clusters are correlated to different rock types, based on laboratory and in situ data. These clusters are remapped back into x–z plane along the profile. Prominent features mapped this way include Salinian granitic rocks beneath and west of SAFOD, and a body of sedimentary rocks faulted beneath these granitic rocks along what we and others interpret to be a branch of the Buzzard Canyon Fault (BCF) system. These sedimentary rocks extend from this fault to the San Andreas fault system. Unfortunately, our cluster analysis shows no significant discontinuity at the San Andreas fault, owing presumably to the fact that the San Andreas fault is located within sedimentary rocks having similar elastic properties. This paper is an attempt to ‘downward’ continue a geological map by geophysical means based on elastic properties of rock samples from the region.

SUMMARY Joint interpretation of models from seismic tomography and inversion of magnetotelluric (MT) data is an efficient approach to determine the lithology of the subsurface. Statistical methods are well established but were developed for only two types of models so far (seismic P velocity and electrical resistivity). We apply self-organizing maps (SOMs), which have no limitations in the number of parameters considered in the joint interpretation. Our SOM method includes (1) generation of data vectors from the seismic and MT images, (2) unsupervised learning, (3) definition of classes by algorithmic segmentation of the SOM using image processing techniques and (4) application of learned knowledge to classify all data vectors and assign a lithological interpretation for each data vector. We apply the workflow to collocated P velocity, vertical P-velocity gradient and resistivity models derived along a 40 km profile around the geothermal site Gros Schonebeck in the Northeast German Basin. The resulting lithological model consists of eight classes covering Cenozoic, Mesozoic and Palaeozoic sediments down to 5 km depth. There is a remarkable agreement between the litho-type distribution from the SOM analysis and regional marker horizons interpolated from sparse 2-D industrial reflection seismic data. The most interesting features include (1) characteristic properties of the Jurassic (low P-velocity gradients, low resistivity values) interpreted as the signature of shales, and (2) a pattern within the Upper Permian Zechstein layer with low resistivity and increased P-velocity values within the salt depressions and increased resistivity and decreased P velocities in the salt pillows. The latter is explained in our interpretation by flow of less dense salt matrix components to form the pillows while denser and more brittle evaporites such as anhydrite remain in place during the salt mobilization.

Automated event localisation results could be improved by transforming amplitudes of waveform to characteristic functions such as trace envelope, STA/LTA, kurtosis and power density function. The goal of this study is to evaluate the performance of Akaike Information Criterion (AIC) function in providing accurate seismic event locations when it is used as the characteristic function. We tested the method to passive seismic data acquired in a local earthquake study around the Sumatran fault, Indonesia. By picking the maximum semblance as event location, our results show that the seismic events delineate Sumatran fault well. We also compared the located seismic events with those computed using the well known STA/LTA characteristic function. By using double-difference results as reference, we found that the located seismic events associated with AIC showing better focusing than STA/LTA results.

Declines in Atlantic bluefin tuna stocks (ABFT, Thunnus thynnus), due to extensive over-fishing, have been widely publicized in recent decades. To counteract this trend, regulatory measures have been introduced by the fisheries managers, aiming at the rebuilding of ABFT stocks. However, apart from difficulties in controlling the implementation of these measures, fisheries management is limited in its capabilities to track their efficiency due to major uncertainties in the stock assessment. Indeed, there is a general need of reliable indicators of ABFT abundance. Aerial surveys may provide a helpful tool for the abundance monitoring of this highly exploited fish species. They are frequently used for the abundance assessment of marine mammals and also by fishermen to detect epipelagic fish, such as tunas. The aim of this thesis was to address these issues and to create a robust fishery-independent abundance index for ABFT through aerial surveys. To achieve this goal, the focus was set on (i) the assessment of factors that potentially affect the detectability of ABFT during the aerial surveys, (ii) the habitat use of ABFT, i.e. their horizontal and vertical behaviour as well as the factors driving it, and (iii) the integration of the knowledge gained through these analyses in the development of a robust index of ABFT abundance. Surveys were conducted from 2000 onwards in the Gulf of Lions, an important nursery ground for ABFT in the Northwestern Mediterranean Sea. Line transect modelling of the sighting data revealed significant effects of detectability changes on abundance estimates, related to the observer teams employed, the size of detected ABFT schools and the sea state during the aerial surveys. Derived estimates of ABFT abundance confirmed a significant increase from 2003 to 2009, likely reflecting the success of recently implemented management measures (e.g. minimum landing size of 30 kg since 2007). To assess behavioural effects on abundance estimates, auxiliary archival tagging experiments, conducted since 2007, focused on the presence and surface availability of ABFT during the aerial surveys, and aimed to identify factors influencing these variables. The data gained from these experiments demonstrated seasonal changes in the migratory behaviour of ABFT, but also a high area and surface presence of ABFT in the study zone during the survey period (August–October), supporting the reliability of the abundance index. Surface presence of ABFT decreased with the breakdown of the thermal stratification of the water column (mid-November), when the fish left the survey zone and moved South. By contrast, deep diving behaviour was particularly frequent during months of high biological productivity (February--May), although deep and unusual long spike dives were also observed during late summer in relation to thermal fronts. However, the variability in the migration patterns indicates a strong opportunistic component in both, the horizontal and vertical behaviour of ABFT, probably related to the availability of food resources. Apart from ABFT, the aerial surveys also allowed an abundance monitoring of fin whales (Balaenoptera physalus) and striped dolphins (Stenella coeruleoalba) as well as an analysis of their co-occurrence with ABFT. In fact, similar to ABFT, the presence of these species appeared to be related to the high productivity and mesoscale activity of the study zone, improving our understanding of their habitat use, essential for the conservation of these much less abundant and endangered species. Regarding the stock assessment of ABFT, the results gained through this thesis prove the feasibility to derive robust fishery independent abundance indicators for ABFT through aerial surveys, providing the theoretical and methodological background for an extension of these efforts for a more sustainable management of the stocks of this species.; Le déclin du thon rouge de l'Atlantique nord-est et de Méditerranée (ABFT, Thunnus thynnus) qui faisait suite à une forte surexploitation a été largement médiatisé au cours de la dernière décennie. Pour contrer cette tendance et reconstituer ce stock, d’importantes mesures de gestion ont été mises en place à partir de 2007. En dehors des difficultés liées à leur mise en œuvre et à leur contrôle, la gestion des pêcheries thonières est aussi limitée dans les capacités à suivre précisément les variations d’abondance de ces espèces dont les observations reposent principalement sur les données de pêche. Le manque d’indice d’abondance fiable fait que l’évaluation du thon rouge, comme celle des autres espèces de poissons grands pélagiques, est entachée d’importantes incertitudes. Cependant, les suivis aériens pourraient permettre de fournir un indice d’abondance du thon rouge. Ils sont en effet fréquemment utilisés pour l'évaluation de l'abondance des mammifères marins et aussi par les pêcheurs pour détecter les poissons épipélagiques, comme les thons. Dans ce contexte général, cette thèse a pour objectifs : (i) d'évaluer des facteurs qui affectent potentiellement la détectabilité des thons pendant les suivis aériens, (ii) d’analyser leur comportement horizontal et vertical et les facteurs environnementaux qui l’influencent, et (iii) d’intégrer les connaissances acquises pour développer un indice abondance robuste du thon rouge en Méditerranée Nord Occidentale. Les analyses reposent sur des suivis aériens conduits depuis 2000 dans le golfe du Lion, une zone de nourricerie importante pour le thon rouge. Une modélisation des données basée sur le « distance sampling » montre des effets significatifs des observateurs, de la taille des bancs de thons et de l'état de la mer sur l’estimation d’abondance. Cette étude confirme par ailleurs une augmentation importance des abondances entre 2003 et 2009, probablement en réponse aux mesures de gestion mises en œuvre depuis 2007 (notamment la taille minimale de débarquement de 30 kg). Pour évaluer les effets du comportement sur les estimations d'abondance, une étude a porté sur les trajectoires de thons issues du marquage électronique. Ces analyses montrent une disponibilité des thons rouge ainsi qu’une présence en surface dans la zone et la période (Août-Octobre) des suivis aériens ; résultat confortant la fiabilité de l’indice d’abondance. On note également des changements saisonniers du comportement, avec un approfondissement des thons à partir de mi-Novembre correspondant à la dé-stratification de la colonne d’eau. Le comportement de plongée profonde était particulièrement fréquent pendant les mois de forte productivité biologique (février-Mai), mais des plongées profondes ont également été observées à la fin de l'été en relation avec des fronts thermiques. La variabilité des schémas migratoires sur l’horizontale et du comportement sur la verticale indique une forte composante opportuniste, probablement liée à la disponibilité des ressources alimentaires. Les résultats obtenus durant cette thèse démontrent la faisabilité d’obtenir un indice d’abondance de thon rouge robuste à partir des suivis aériens (donc indépendants des données de pêche) et fournissent un cadre théorique et méthodologique pour une extension de ce type de suivi afin de diminuer les incertitudes autour de l’évaluation de ce stock. Outre le thon rouge, les suivis aériens ont également permis un suivi du rorqual commun (Balaenoptera physalus) et des dauphins rayés (Stenella coeruleoalba). La présence des mammifères marins semble également être liée à la productivité élevée et l'activité méso-échelle de la zone d'étude. Si les dauphins présentent une distribution spatiale en partie corrélée à celle du thon rouge, les rorquals ne présentent pas de forte co-occurrence avec le thon rouge, résultat qui confirmerait une certaine proximité des régimes alimentaires des thons et des dauphins.

The Dead Sea is a prime location to study the structure and development of pull‐apart basins. We analyzed tomographic models of Vp, Vs, and Vp/Vs using self‐organizing map clustering techniques. The method allows us to identify major lithologies by their petrophysical signatures. Remapping the clusters into the subsurface reveals the distribution of basin sediments, prebasin sedimentary rocks, and crystalline basement. The Dead Sea basin shows an asymmetric structure with thickness variation from 5 km in the west to 13 km in the east. Most importantly, we identified a distinct, well‐defined body under the eastern part of the basin down to 18 km depth. Considering its geometry and petrophysical signature, this unit is interpreted as a buried counterpart of the shallow prebasin sediments encountered outside of the basin and not as crystalline basement. The seismicity distribution supports our results, where events are concentrated along boundaries of the basin and the deep prebasin sedimentary body. Our results suggest that the Dead Sea basin is about 4 km deeper than assumed from previous studies.

In this paper, nuclear magnetic resonance (NMR) downhole logging data are analyzed with a new strategy to study gas hydrate-bearing sediments in the Mackenzie Delta (NW Canada). In NMR logging, transverse relaxation time (T2) distribution curves are usually used to determine single-valued parameters such as apparent total porosity or hydrocarbon saturation. Our approach analyzes the entire T2 distribution curves as quasi-continuous signals to characterize the rock formation. We apply self-organizing maps, a neural network clustering technique, to subdivide the data set of NMR curves into classes with a similar and distinctive signal shape. The method includes (1) preparation of data vectors, (2) unsupervised learning, (3) cluster definition, and (4) classification and depth mapping of all NMR signals. Each signal class thus represents a specific pore size distribution which can be interpreted in terms of distinct lithologies and reservoir types. A key step in the interpretation strategy is to reconcile the NMR classes with other log data not considered in the clustering analysis, such as gamma ray, hydrate saturation, and other logs. Our results defined six main lithologies within the target zone. Gas hydrate layers were recognized by their low signal amplitudes for all relaxation times. Most importantly, two subtypes of hydrate-bearing shaly sands were identified. They show distinct NMR signals and differ in hydrate saturation and gamma ray values. An inverse linear relationship between hydrate saturation and clay content was concluded. Finally, we infer that the gas hydrate is not grain coating, but rather, pore filling with matrix support is the preferred growth habit model for the studied formation.

Imaging techniques which provide the spatial distribution of microseismic events are increasingly used to monitor the behaviour of geothermal reservoirs during production. As seismometers are installed for longer time, the volume of recorded data volumes are getting too large to apply classical approaches of seismological event localization. We developed a seismic event localization method which is called “shift delay and stack” (SDS) which is based on the depth migration of a characterstic function (CF) derived from the recorded wavefield. The depth location of the event is determined based on the global maximum of a coherency function. We also introduce a new kurtosis-based CF which enhances the onset of the P-wave arrivals. No picking is needed to apply the SDS method for event localization, hence data preparation and processing time can be reduced. The SDS method is applied to the microseismic data recorded at a geothermal field in Indonesia. The results show that the SDS method is capable of producing reliable event locations. The location uncertainty can be deduced from the results. Two previously known N-S trending faults are successfully detected by the algorithm. Moreover, the extension of the productive reservoir volume can be identified by our investigation.