Global and Local Multiscale Analysis of Magnetic Susceptibility Data   总被引：3，自引：0，他引：3  

Maurizio?FediEmail author 《Pure and Applied Geophysics》2003,160(12):2399-2417

Geophysical well-logs often show a complex behavior which seems to suggest a multifractal nature. Multifractals are highly intermittent signals, with distinct active bursts and passive regions which cannot be satisfactorily characterized in terms of just second-order statistics. They need a higher-order statistical analysis. In contrast with monofractals which have a homogeneous scaling, multifractals may include singularities of many types. Here we describe how a multiscale analysis can be used to describe the magnetic susceptibility data scaling properties for a deep well (KTB, Germany), down to about 9000 m. A multiscale analysis describes the local and global singular behavior of measures or distributions in a statistical fashion. The global analysis allows the estimation of the global repartition of the various Holder exponents. As such, it leads to the definition of a spectrum, D(), called the singularity spectrum. The local analysis is related to the possibility of estimating the Lipschitz regularity locally, i.e., at each point of the support of a multifractal signal. The application of both approaches to the KTB magnetic susceptibility data shows a meaningful correlation between the sequence of Holder exponents vs. depth and the lithological units. The Holder exponents reach the highest values for gneiss units, intermediate ones for amphibolite units and the lowest values for variegated units. Faults are found to correspond to changes for H also when they are of intra-lithological type.  相似文献   

Mainshocks and aftershocks of the 2002 molise seismic sequence, southern Italy     

C. Chiarabba  P. De Gori  L. Chiaraluce  P. Bordoni  M. Cattaneo  M. De Martin  A. Frepoli  A. Michelini  A. Monachesi  M. Moretti  G. P. Augliera  E. D'Alema  M. Frapiccini  A. Gassi  S. Marzorati  P. Di Bartolomeo  S. Gentile  A. Govoni  L. Lovisa  M. Romanelli  G. Ferretti  M. Pasta  D. Spallarossa  E. Zunino 《Journal of Seismology》2005,9(4):487-494

In October and November 2002, the Molise region (southern Italy) was struck by two moderate magnitude earthquakes within 24 hours followed by an one month long aftershocks sequence. Soon after the first mainshock (October 31st, 10.32 UTC, M_w 5.7), we deployed a temporary network of 35 three-component seismic stations. At the time of occurrence of the second main event (November 1st, 15.08 UTC, M_w 5.7) the eight local stations already installed allowed us to well constrain the hypocentral parameters. We present the location of the two mainshocks and 1929 aftershocks with 2 < M_L < 4.2. Earthquake distribution reveals a E-trending 15 km long fault system composed by two main segments ruptured by the two mainshocks. Aftershocks define two sub-vertical dextral strike-slip fault segments in agreement with the mainshock fault plane solutions. P- and T-axes retrieved from 170 aftershocks focal mechanisms show a coherent kinematics: with a sub-horizontal NW and NE-trending P and T-axes, respectively. For a small percentage of focal mechanisms (∼ 10%) a rotation of T axes is observed, resulting in thrust solutions. The Apenninic active normal fault belt is located about 80 km westward of the 2002 epicentral area and significant seismicity occurs only 20-50 km to the east, in the Gargano promontory. Seismic hazard was thought to be small for this region because neither historical earthquake are reported in the Italian seismic catalogue or active faults were previously identified. In this context, the 2002 seismic sequence highlights the existence of trans-pressional active tectonics in between the extensional Apenninic belt and the Apulian foreland.  相似文献   

Lava effusion rates from hand-held thermal infrared imagery: an example from the June 2003 effusive activity at Stromboli     

Andrew Harris  Jon Dehn  Matt Patrick  Sonia Calvari  Maurizio Ripepe  Luigi Lodato 《Bulletin of Volcanology》2005,68(2):107-117

A safe, easy and rapid method to calculate lava effusion rates using hand-held thermal image data was developed during June 2003 at Stromboli Volcano (Italy). We used a Forward Looking Infrared Radiometer (FLIR) to obtain images of the active lava flow field on a daily basis between May 31 and June 16, 2003. During this time the flow field geometry and size (where flows typically a few hundred meters long were emplaced on a steep slope) meant that near-vertical images of the whole flow field could be captured in a single image obtained from a helicopter hovering, at an altitude of 750 m and ∼1 km off shore. We used these images to adapt a thermally based effusion rate method, previously applied to low and high spatial resolution satellite data, to allow automated extraction of effusion rates from the hand-held thermal infrared imagery. A comparison between a thermally-derived (0.23–0.87 m³ s⁻¹) and dimensionally-derived effusion rate (0.56 m³ s⁻¹) showed that the thermally-derived range was centered on the expected value. Over the measurement period, the mean effusion rate was 0.38±0.25 m³ s⁻¹, which is similar to that obtained during the 1985–86 effusive eruption and the time-averaged supply rate calculated for normal (non-effusive) Strombolian activity. A short effusive pulse, reaching a peak of ∼1.2 m³ s⁻¹, was recorded on June 3, 2003. One explanation of such a peak would be an increase in driving pressure due to an increase in the height of the magma contained in the central column. We estimate that this pulse would require the magma column to attain a height of ∼190 m above the effusive vent, which is approximately the elevation difference between the vent and the floor of the NE crater. Our approach gives an easy-to-apply method that has the potential to provide effusion rate time series with a high temporal resolution.Editorial responsibility: M. Carroll  相似文献   

The distribution of Cu(II) and the magnetic properties of the synthetic analogue of tetrahedrite: Cu12Sb4S13     

F. Di Benedetto  G. P. Bernardini  C. Cipriani  C. Emiliani  D. Gatteschi  M. Romanelli 《Physics and Chemistry of Minerals》2005,32(3):155-164

A wide investigation of the synthetic analogue of tetrahedrite, Cu₁₂Sb₄S₁₃, has been performed by a combination of several techniques, magnetisation and differential scanning calorimetric measurements, cw, and pulsed EPR spectroscopy, to obtain complementary information about the presence and the distribution of Cu(II). The high temperature susceptibility of the sample accounts for two Cu(II) per formula unit, in agreement with the charge balance. However, strong antiferromagnetic interactions, observed even at room temperature, are associated with a transition at 83(3) K. At lower temperatures a residual susceptibility is observed. At 4.2 K ESEEM experiments enabled observation of the chemical environment of the residual paramagnetic species. Cu(II) was found randomly distributed in the M(1) site. The statistical presence of nearest neighbouring Cu(II) ions justify the observed antiferromagnetic interactions and transition. Nevertheless, isolated paramagnetic ions have been determined below the Néel temperature: they are mainly located near the surface of the grains. A colour centre, previously observed in natural samples, has been also identified.  相似文献   

Strombolian explosive styles and source conditions: insights from thermal (FLIR) video   总被引：1，自引：3，他引：1  

Matthew R. Patrick  Andrew J. L. Harris  Maurizio Ripepe  Jonathan Dehn  David A. Rothery  Sonia Calvari 《Bulletin of Volcanology》2007,69(7):769-784

Forward Looking Infrared Radiometer (FLIR) cameras offer a unique view of explosive volcanism by providing an image of calibrated temperatures. In this study, 344 eruptive events at Stromboli volcano, Italy, were imaged in 2001–2004 with a FLIR camera operating at up to 30 Hz. The FLIR was effective at revealing both ash plumes and coarse ballistic scoria, and a wide range of eruption styles was recorded. Eruptions at Stromboli can generally be classified into two groups: Type 1 eruptions, which are dominated by coarse ballistic particles, and Type 2 eruptions, which consist of an optically-thick, ash-rich plume, with (Type 2a) or without (Type 2b) large numbers of ballistic particles. Furthermore, Type 2a plumes exhibited gas thrust velocities (>15 m s⁻¹) while Type 2b plumes were limited to buoyant velocities (<15 m s⁻¹) above the crater rim. A given vent would normally maintain a particular gross eruption style (Type 1 vs. 2) for days to weeks, indicating stability of the uppermost conduit on these timescales. Velocities at the crater rim had a range of 3–101 m s⁻¹, with an overall mean value of 24 m s⁻¹. Mean crater rim velocities by eruption style were: Type 1 = 34 m s⁻¹, Type 2a = 31 m s⁻¹, Type 2b = 7 m s⁻¹. Eruption durations had a range of 6–41 s, with a mean of 15 s, similar among eruption styles. The ash in Type 2 eruptions originates from either backfilled material (crater wall slumping or ejecta rollback) or rheological changes in the uppermost magma column. Type 2a and 2b behaviors are shown to be a function of the overpressure of the bursting slug. In general, our imaging data support a broadening of the current paradigm for strombolian behavior, incorporating an uppermost conduit that can be more variable than is commonly considered.  相似文献   

A geological transect from Kun Lun to Karakorum (Sinkiang, China): the western termination of the Tibetan Plateau. Preliminary note     

Maurizio Gaetani  Guido Gosso  Ugo Pognante 《地学学报》1990,2(1):23-30

A geological-geophysical expedition (Ev-K2–CNR 1988) visited the area from West Kun Lun to Karakorum (K2–Gasherbrum). Seven tectonic units including sedimentary, magmatic and metamorphic rocks were distinguished in this area; the northernmost are suggested to belong to the Kun Lun and Qiangtang Microplates. The sedimentary sequence of Shaksgam is proved to extend from the Permian to the Jurassic, with Carboniferous and Cretaceous ages more doubtful. This sequence shows intermediate affinities between the Karakorum and the Qiangtang. The two southernmost units belong to the Karakorum Microplate. The Karakorum Fault Zone comprises a complex pattern of faults and thrusts, with brittle deformation and uplifting of granitoid bodies.  相似文献   

An Observational Method to Prevent Cross-Talk and Calibrate Mof-Based Instruments     

Maria Magrì  Maurizio Oliviero  Giuseppe Severino 《Solar physics》2005,232(1-2):159-170

We present a method for calibrating every instrument working with magneto-optical filter (MOF) technology, in order to take into account the effect in the observations due to the aging of the vapour cells. The method allows the evaluation of some characteristics of the transmission profile by modelling the blue and/or the red line intensity images acquired with the MOF system. In particular, it reveals the presence of unwanted spurious transmissions and prevents cross-talk between the intensity and velocity fluctuations. The method also gives information about the position of the “working point” of the instrument, i.e. the average wavelength position of its transmission profile, which is necessary for estimating the right solar atmospheric layer observed by the MOF. This analysis is powerful and fast: applied before every observing campaign, it enables setting Q the most suitable value for the cell temperature, which is one of the parameters that controls the MOF transmission profile.  相似文献   

Evaluation of local amplification in the seismic microzonation: comparison between punctual multidisciplinary integrated studies and macroseismic methods in Fivizzano's area (Toscana, Italy)     

Patrizio Signanini  Vittorio D'Intinosante  Maurizio Ferrini  Mario L. Rainone 《Geotechnical and Geological Engineering》2004,22(2):227-244

In the seismic microzonation the evaluation of the local amplification issue may be solved using different methodological approaches. Taking the hint from the studies made within VEL project framework, sponsored by Tuscany Region on Fivizzano's area we are herewith comparing the results of geotechnical and geophysical integrated multidisciplinary studies with the existing data available from previous studies, mainly using a macroseismic approach, on the same area. This qualitative method does not seem to be able to make any forecasting on the scale whereas generally microzoning is performed. On the contrary, the knowledge of the geological-technical model of the investigated area, obtained by punctual multidisciplinary integrated studies, allows a direct collection of the data to insert in input step of numerical modelling, aimed to local effects evaluation. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Daily Milan Temperature and Pressure Series (1763–1998): Completing and Homogenising the Data     

Maurizio Maugeri  Letizia Buffoni  Barbara Delmonte  Adriana Fassina 《Climatic change》2002,53(1-3):119-149

Daily meteorological observations have been made at the Brera astronomical observatory in Milan since 1763. Even if the data have always been collected at this observatory, the Milan series are far from being homogeneous as several changes were made to instruments, station location and observation methods. Within this context, the purpose of the paper is to discuss data homogenisation. Homogenisation is based both on objective information extracted from the station history (direct methodology) and on some statistical estimates (indirect methodology). Homogenisation by indirect methodology is mainly performed by comparison with other series whereas, if no other homogeneous series are available, it is based on the hypothesis that some statistics, such as the daily temperature range or the day to day variability, have no significant trends within some selected periods. Besides homogenisation also the completion of the series is discussed. Theresulting series are complete and homogenised daily minimum, mean and maximum temperatures and complete and homogenised daily mean pressures. They all cover the period 1763–1998.  相似文献   

The edge dislocation problem in a layered elastic medium   总被引：2，自引：0，他引：2  

Eleonora Rivalta  Walter Mangiavillano  Maurizio Bonafede 《Geophysical Journal International》2002,149(2):508-523

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