Review of Modeling Approaches to Groundwater Flow in Deformed Carbonate Aquifers

We discuss techniques to represent groundwater flow in carbonate aquifers using the three existing modeling approaches: equivalent porous medium, conduit network, and discrete fracture network. Fractures in faulted stratigraphic successions are characterized by dominant sets of sub-vertical joints. Grid rotation is recommended using the equivalent porous medium to match higher hydraulic conductivity with the dominant orientation of the joints. Modeling carbonate faults with throws greater than approximately 100 m is more challenging. Such faults are characterized by combined conduit-barrier behavior. The barrier behavior can be modeled using the Horizontal Flow Barrier Package with a low-permeability vertical barrier inserted to represent the impediment of horizontal flow in faults characterized by sharp drops of the piezometric surface. Cavities can occur parallel to the strike of normal faults generating channels for the groundwater. In this case, flow models need to account for turbulence using a conduit network approach. Channels need to be embedded in an equivalent porous medium due to cavities a few centimeters large, which are present in carbonate aquifers even in areas characterized by low hydraulic gradients. Discrete fracture network modeling enables representation of individual rock discontinuities in three dimensions. This approach is used in non-heavily karstified aquifers at industrial sites and was recently combined with the equivalent porous medium to simulate diffusivity in the matrix. Following this review, we recommend that the future research combines three practiced modeling approaches: equivalent porous medium, discrete fracture network, and conduit network, in order to capture structural and flow aspects in the modeling of groundwater in carbonate rocks.     

Structural evolution of the '41st parallel zone': Tyrrhenian Sea

The present study is based on the interpretation of more than 1300 km of 16 kJ sparker seismic profiles recorded in July 1990, during the Cruise T-41 of the Geological Institute of Urbino. The investigated area extends along the 41st parallel in the central Tyrrhenian Sea between the northern Sardinian margin to the west and the Latium–Campanian margin to the east. This zone, situated on continental crust, marks the boundary between the northern Tyrrhenian and the southern Tyrrhenian domains. A kinematic reconstruction is presented, based on the age-dating of the recognized structures (i.e. normal faults, reverse faults, anticline and flower structures). The evolution of the ‘41st parallel zone’ can be described in terms of polyphase tectonics characterized by different orientations of the stress field during time. The direction of the normal fault-trends, turned clockwise, striking NE–SW in the late Tortonian–Messinian, E–W in the early Pliocene, NNW–SSE in the late Pliocene and N–S during the Quaternary. The concurrence of compressional and strike-slip deformations suggests oblique shear motions across the 41st parallel. The occurrence of late Pliocene–Quaternary tectonic activity in the northern Tyrrhenian Sea, locally characterized by inversion tectonics, suggests active mechanisms (intraplate compression?) superimposed on the post-rift subsidence.     

Acoustically estimated size distribution of sperm whales (Physeter macrocephalus) off the east coast of New Zealand

ABSTRACT

The length-frequency distribution of sperm whales (Physeter macrocephalus) was studied on the east coast of NZ using passive acoustic recorders moored offshore of Kaikoura, Cape Palliser and Castlepoint. Sperm whale’s echolocation signals are unique among odontocete species. Their clicks are composed by multiple pulses resulting from the sound transmission within the whale head. The total length of the whales can be estimated by measuring the time delay between these pulses. A total of 997 length measurements were obtained from click trains using cepstral analysis (mean?=?14.6?m; min?=?9.6?m; max?=?18.3?m; std?=?1?m). The size-frequency distributions at all three locations were similar, although animals smaller than 12?m were not present offshore of Kaikoura. Animals of various sizes appeared to be present all year round, with no apparent seasonality in the occurrence of any size class.     

Eine durch Tiefengesteinskontakt veränderte Uranlagerstätte

Zusammenfassung Die vorliegende Untersuchung befaßt sich mit einer Uranvererzung der permischen Sandsteine, welche sich in unmittelbarer Nähe des granodioritisch-tonalitischen Adamello-Plutons befunden hat. Geographisch liegen diese Vererzungen im westlichen Teil des Massivs, etwa bei 2120 m ü. d. M. In bezug auf den Mineralbestand und die Verwachsungen ist zu betonen, daß eine wohl zu erwartende allgemeine Mobilisierung und Rekristallisation der ursprünglichen Vererzung- — und des Nebengesteins —, zusammen aber mit z. T. auffallend mangelhaften Gleichgewichtseinstellungen vor sich gegangen sind. Bemerkenswert ist u. a. die Neubildung einer noch nicht bekannten Vanadium- und Eisen-Silikat-Verbindung.

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In this paper is investigated a uranium deposit in permian sandstones, which was situated in immediate neighbourhood to the granodioritic-tonalitic Adamello-pluton. The deposit occurs in the western part of the massiv, at an altitude of 2100 meter. With regard to the mineral associations and the related intergrowths it should be pointed out that the obvious phenomena related to the mobilisation and the recrystallisation of the ore — and of the ore bearing rocks —, are sometimes characterized by an evidently uncomplete equilibrium. Remarkable is the formation of a still unknown vanadium- and ironbearing opaque mineral.

     

On the efficiency and effectiveness of automatic deep drainage systems during an extreme rainfall event: the Mendatica landslide case study (western Liguria,Italy)

Landslides - This study presents the employment of automatic deep drainage systems to stabilize the Mendatica landslide, one of the largest relict landslides of western Liguria (north-western...     

浅源强震至浅源特大地震震级M_e的快速测定

提出了根据20°～90°距离范围之内的宽频带远震P波信号快速测定浅源地震能量震级Me的新程序。为了完成这项工作,我们根据地球参考模型AK135Q用数字模拟方法计算了不同周期的频谱振幅衰减函数。根据这些函数,我们校正了远震记录频谱的传播路径效应,计算了地震辐射能量Es和震级Me。我们用累积的P波窗模拟实时或近实时的程序,并用61个浅源地震进行验证。结果表明,我们的方法可在地震发震时刻后的7～15min内迅速可靠地测定出震级Me因此,这一程序适用于快速反应系统的实施。     

A scheme to set preferred magnitudes in the ISC Bulletin

One of the main purposes of the International Seismological Centre (ISC) is to collect, integrate and reprocess seismic bulletins provided by agencies around the world in order to produce the ISC Bulletin. This is regarded as the most comprehensive bulletin of the Earth’s seismicity, and its production is based on a unique cooperation in the seismological community that allows the ISC to complement the work of seismological agencies operating at global and/or local-regional scale. In addition, by using the seismic wave measurements provided by reporting agencies, the ISC computes, where possible, its own event locations and magnitudes such as short-period body wave m _b and surface wave M _S . Therefore, the ISC Bulletin contains the results of the reporting agencies as well as the ISC own solutions. Among the most used seismic event parameters listed in seismological bulletins, the event magnitude is of particular importance for characterizing a seismic event. The selection of a magnitude value (or multiple ones) for various research purposes or practical applications is not always a straightforward task for users of the ISC Bulletin and related products since a multitude of magnitude types is currently computed by seismological agencies (sometimes using different standards for the same magnitude type). Here, we describe a scheme that we intend to implement in routine ISC operations to mark the preferred magnitudes in order to help ISC users in the selection of events with magnitudes of their interest.     

Addressing some critical aspects of the BepiColombo MORE relativity experiment

The Mercury Orbiter Radio science Experiment (MORE) is one of the experiments on-board the ESA/JAXA BepiColombo mission to Mercury, to be launched in October 2018. Thanks to full on-board and on-ground instrumentation performing very precise tracking from the Earth, MORE will have the chance to determine with very high accuracy the Mercury-centric orbit of the spacecraft and the heliocentric orbit of Mercury. This will allow to undertake an accurate test of relativistic theories of gravitation (relativity experiment), which consists in improving the knowledge of some post-Newtonian and related parameters, whose value is predicted by General Relativity. This paper focuses on two critical aspects of the BepiColombo relativity experiment. First of all, we address the delicate issue of determining the orbits of Mercury and the Earth–Moon barycenter at the level of accuracy required by the purposes of the experiment and we discuss a strategy to cure the rank deficiencies that appear in the problem. Secondly, we introduce and discuss the role of the Solar Lense–Thirring effect in the Mercury orbit determination problem and in the relativistic parameters estimation.