Coordinated optical and radar image measurements of noctilucent clouds and polar mesospheric summer echoes

Novel coincident 3-D radar, lidar and optical image measurements of dynamical structures in polar mesosphere summer echoes (PMSE) and noctilucent clouds (NLC) are presented. Common volume mesospheric measurements were made over central Alaska using the new Poker Flat Incoherent Scatter Radar (PFISR), a co-located Rayleigh lidar and remote, two-station digital image observations, enabling the first detailed investigation of the horizontal and vertical structures of NLC and PMSE. Coincident measurements were made of an unusual NLC display recorded on 10–11 August 2007, characterized by a broad luminous band that contained several prominent wave forms. Concurrent lidar and image measurements established the presence of NLC within the radar volume from ～09:00 UT (01:00 LT), when the solar depression angle was 10.4°, until dawn. Strong but intermittent PMSE were detected by PFISR, with distinct patchy structures that exhibited a similar southward motion as the NLC. Detailed comparison of the 3-D PMSE structures and the NLC lidar and image data have revealed striking similarities when account was taken of the NLC layer altitude, suggesting a direct link between their small-scale spatial signatures (within the current resolution of the radar measurements). At the same time, the lidar detected a sustained increase in the backscatter signal, while the imagers revealed the development of copious short horizontal wavelength (4.9 km) billow waves. We conclude that strong wind shears associated with the Kelvin–Helmholtz billow instabilities played a key role in the development of a neutral turbulence layer in close proximity to the NLC layer resulting in the strong but intermittent PMSE detected at 450 MHz on this occasion.     

First incoherent scatter radar observations of ionospheric heating on the second electron gyro-harmonic

We report first results from a unique experiment performed at the HIPAS ionospheric modification facility in conjunction with the Poker Flat incoherent scatter radar in Alaska. High-power radio waves at 2.85 MHz, which corresponds to the second electron gyro-harmonic at ~245 km altitude, were transmitted into the nighttime ionosphere. Clear evidence of F-region ionospheric electron temperature enhancements were found, for the first time at this pump frequency, maximizing when the pump frequency is close to the second gyro-harmonic and double resonance. This is consistent with previous pump-enhanced artificial optical observations. We estimate the plasma heating efficiency to be approximately double that for higher pump frequencies.     

Latitudinal and seasonal variability of the micrometeor input function: A study using model predictions and observations from Arecibo and PFISR

In this work, we use a semi-empirical model of the micrometeor input function (MIF) together with meteor head-echo observations obtained with two high power and large aperture (HPLA) radars, the 430 MHz Arecibo Observatory (AO) radar in Puerto Rico (18°N, 67°W) and the 450 MHz Poker flat incoherent scatter radar (PFISR) in Alaska (65°N, 147°W), to study the seasonal and geographical dependence of the meteoric flux in the upper atmosphere. The model, recently developed by Janches et al. [2006a. Modeling the global micrometeor input function in the upper atmosphere observed by high power and large aperture radars. Journal of Geophysical Research 111] and Fentzke and Janches [2008. A semi-empirical model of the contribution from sporadic meteoroid sources on the meteor input function observed at arecibo. Journal of Geophysical Research (Space Physics) 113 (A03304)], includes an initial mass flux that is provided by the six known meteor sources (i.e. orbital families of dust) as well as detailed modeling of meteoroid atmospheric entry and ablation physics. In addition, we use a simple ionization model to treat radar sensitivity issues by defining minimum electron volume density production thresholds required in the meteor head-echo plasma for detection. This simplified approach works well because we use observations from two radars with similar frequencies, but different sensitivities and locations. This methodology allows us to explore the initial input of particles and how it manifests in different parts of the MLT as observed by these instruments without the need to invoke more sophisticated plasma models, which are under current development. The comparisons between model predictions and radar observations show excellent agreement between diurnal, seasonal, and latitudinal variability of the detected meteor rate and radial velocity distributions, allowing us to understand how individual meteoroid populations contribute to the overall flux at a particular location and season.     

PMSE observations at three different frequencies in northern Europe during summer 1994

Simultaneous observations of polar mesosphere summer echoes (PMSE) have been carried out during summer 1994 in northern Norway using three radars on different frequencies: the ALOMAR SOUSY radar at Andenes on 53.5 MHz, the EISCAT VHP radar at Tromsø on 224 MHz and the MF radar at Tromsø on 2.78 MHz. During the common measuring period in July/August 1994, PMSE could be detected at 224 and 53.5 MHz, and there are strong hints that PMSE also occur at 2.78 MHz. Reliable correlations between hourly backscattered power values indicate that the PMSE structures have zonal extensions of more than 130 km and can be detected at very different scales (half wavelength) between 0.67 (EISCAT VHP radar) and 54 m (MF radar). Using the wind values derived by the MF radar it can be shown that the mesospheric wind field influences the structure of PMSE. The diurnal variation of PMSE is strongly connected with tidal-wind components, whereas spatial differences of PMSE can partly be explained by the mean wind field.     

Inter-hemispheric asymmetry in polar mesosphere summer echoes and temperature at 69° latitude

An inter-hemispheric asymmetry is found in the characteristics of polar mesosphere summer echoes (PMSE) and upper mesosphere temperatures at conjugate latitudes (～69°) above Antarctica and the Arctic. The second complete mesosphere–stratosphere–troposphere (MST) radar summer observation season at Davis (68.6°S) revealed that PMSE occur less frequently, with lower strength and on average 1 km higher compared with their northern counterparts at Andenes (69.3°N). We consider the thermodynamic state of the mesosphere for conjoining hemispheric summers based on satellite and ground-based radar measurements, and show the mesopause region near ～80–87 km of the Southern Hemisphere (SH) to be up to 7.5 K warmer than its Northern Hemisphere (NH) counterpart. We show that this is consistent with our observation of asymmetries in the characteristics of PMSE and demonstrate how the mesosphere meridional wind field influences the existence and strength of the echoes in both hemispheres.     

Determination of physical and radiant meteor properties using PFISR interferometry measurements of head echoes

Over the past decade, High Power and Large Aperture (HPLA) radars have been widely utilized for the study of sub-millimeter extraterrestrial particles via the detection of the meteor head-echo. These observations have been a successful tool in the study of the sporadic meteor background, however, they have been limited by the lack of precise knowledge of the particle's location within the radar beam and its absolute trajectory and velocity. This limitation prevents for example the accurate determination of the meteors radiant and orbit. Interferometry measurements of the head-echo has been proven to be a detection technique that satisfies this need. Unfortunately very few radars are capable of performing them. We have developed a methodology which takes advantage of the multi-receiving capabilities of the 450 MHz Poker Flat Incoherent Scatter Radar (PFISR) enabling us to utilize the phased array of crossed-dipoles as an interferometer. This new PFISR capability allows us to determine the instantaneous position of meteors within the radar beam. This enables us to determine absolute velocities and ultimately meteor radiant and orbit around the Sun. In this work, we present initial results from 9 h of observations during which 142 particles were individually detected by the three different receiving channels simultaneously. For these meteors absolute velocities were obtained and meteor dynamical, physical and radiant properties were derived.     

40Ar / 39Ar geochronology constraints on late miocene weathering rates in Minas Gerais,Brazil

⁴⁰Ar / ³⁹Ar incremental heating ages for twenty one grains of cryptomelane, collected at 0, 42, 45, and 60 m depths in the Cachoeira Mine weathering profile, Minas Gerais, permit calculating long-term (10 Ma time scale) weathering rate (saprolitization rate) in SE Brazil. Pure well-crystallized cryptomelane grains with high K contents (3–5 wt.%) yield reliable geochronological results. The ⁴⁰Ar / ³⁹Ar plateau ages obtained decrease from the top to the bottom of the profile (12.7 ± 0.1 to 7.6 ± 0.1 Ma at surface; 7.6  ± 0.2 to 6.1 ± 0.2 Ma at 42 m; and 7.1 ± 0.2 to 5.9 ± 0.1 Ma at 45 m; 6.6 ± 0.1 to 5.2 ± 0.1 Ma at 60 m), yielding a weathering front propagation rate of 8.9 ± 1.1 m/m.y. From the geochronological results and the mineral transformations implicit by the current mineralogy in the weathering profiles, it is possible to calculate the saprolitization rate for the Cachoeira Mine lithologies and for adjacent weathering profiles developed on granodiorites and schists. The measured weathering front propagation rate yields a saprolitization rate of 24.9 ± 3.1 t/km²/yr. This average long-term (> 10 Ma) saprolitization rate is consistent with mass balance calculations results for present saprolitization rates in weathering watersheds. These results are also consistent with long-term saprolitization rates estimated by combining cosmogenic isotope denudation rates with mass balance calculations.     

Detection of large scale TIDs associated with the dayside cusp using SuperDARN data

Variations in the dayside ionosphere parameters as a result of a large-scale acoustic gravity wave (LS AGW) were studied for the 17 February 1998 substorm using the super dual auroral radar network (SuperDARN) measurements. This event was characterised by a sharp rise in the AE index with a maximum of ～900 nT. The source of the disturbance responsible for the LS AGW appears to have been located within the plasma convection throat and in the dayside cusp region. The location of the source was obtained from studies of a number of datasets including high-latitude convection maps, data from 4 DMSP satellites and networks of ground-based magnetometers. The propagation of the LS AGWs caused quasi-periodic variations in the skip distance (with an amplitude up to 220–260 km) of the ground backscatter measured by up to 6 SuperDARN radars, including Goose Bay and Kapuskasing, resulting in two large-scale travelling ionospheric disturbances (LS TIDs). The LS TIDs had wave periods of 1.5 and 2 h, a velocity of ～400 m/s for both, and wavelengths of 2200 and 2900 km, respectively. These quasi-periodic variations were also present in the peak electron density and height of the F2 layer measured by the Goose Bay ionosonde. The numerical simulation of the inverse problem show good agreement between Goose Bay radar and Goose Bay ionosonde measurements. But these LS TIDs would be difficult to deduce from the ground based ionospheric station data alone, because h_mF2 variations were 10–40 km only and f_OF2 variations between 10% and 20%. The results demonstrate how important SuperDARN radars can be, and that this is a more powerful technique than routine ground-based sounding for studies of weak quasi-periodic variations in the dayside subauroral ionosphere related to LS AGW.     

TEC variations over the Mediterranean before and during the strong earthquake (M = 6.5) of 12th October 2013 in Crete,Greece

In this paper, the total electron content (TEC) data from eight global positioning system (GPS) stations of the EUREF network, provided by IONOLAB (Turkey), were analyzed using discrete Fourier analysis to investigate the TEC variations over the Mediterranean before and during the strong earthquake of 12th October 2013, which occurred west of Crete, Greece. In accordance with the results of similar analyses in the area, the main conclusions of this study are the following: (a) TEC oscillations in a broad range of frequencies occur randomly over an area of several hundred km from the earthquake and (b) high frequency oscillations (f ⩾ 0.0003 Hz, periods T ⩽ 60 m) may point to the location of the earthquake with questionable accuracy. The fractal characteristics of the frequency distribution may point to the locus of the earthquake with higher accuracy. We conclude that the lithosphere–atmosphere–ionosphere coupling (LAIC) mechanism through acoustic or gravity waves could explain this phenomenology.     

Time-Domain Moment Tensors for shallow (h ≤ 40 km) earthquakes in the broader Aegean Sea for the years 2006 and 2007: The database of the Aristotle University of Thessaloniki

We present a catalog of moment tensor (MT) solutions and moment magnitudes, M_w, for 119 shallow (h ≤ 40 km) earthquakes in Greece and its surrounding lands (34°N–42°N, 19°E–30°E) for the years 2006 and 2007, computed with the 1D Time-Domain Moment Tensor inversion method (TDMT_INV code of Dreger, 2003). Magnitudes range from 3.2 ≤ M_w ≤ 5.7. Green's functions (GF) have been pre-computed to build a library, for a number of velocity profiles applicable to the broader Aegean Sea region, to be used in the inversion of observed broad band waveforms (10–50 s). All MT solutions are the outcome of a long series of tests of different reported source locations and hypocenter depths. Quality factors have been assigned to each MT solution based on the number of stations used in the inversion and the goodness of fit between observed and synthetic waveforms. In general, the focal mechanisms are compatible with previous knowledge on the seismotectonics of the Aegean area. The new data provide evidence for strike-slip faulting along NW–SE trending structures at the lower part of Axios basin, close to the heavily industrialized, and presently subsiding, region of the city of Thessaloniki. Normal faulting along E–W trending planes is observed at the Strimon basin, and in Orfanou Gulf in northern Greece. A sequence of events in the east Aegean Sea close to the coastline with western Anatolia sheds light on an active structure bounding the north coastline of Psara–Chios Islands about 20–25 km in length exhibiting right lateral strike-slip faulting.     

Systematic tapping of independent magma chambers during the 1 Ma Kidnappers supereruption

The 1.0 Ma Kidnappers supereruption (~ 1200 km³ DRE) from Mangakino volcanic centre, Taupo Volcanic Zone, New Zealand, produced a large phreatomagmatic fall deposit followed by an exceptionally widespread ignimbrite. Detailed sampling and analysis of glass shards and mineral phases have been undertaken through a proximal 4.0 m section of the fall deposit, representing the first two-thirds of erupted extra-caldera material. Major and trace element chemistries of glass shards define three distinct populations (types A, B and C), which systematically change in proportion through the fall deposit and are inferred to represent three magma types. Type B glass and biotite first appear at the same level (~ 0.95 m above base) in the fall deposit suggesting later tapping of a biotite-bearing magma. Plagioclase and Fe–Ti oxide compositions show bimodal distributions, which are linked to types A and B glass compositions. Temperature and pressure (T–P) estimates from hornblende and Fe–Ti oxide equilibria from each magma type are similar and therefore the three magma bodies were adjacent, not vertically stacked, in the crust. Most hornblende model T–P estimates range from 770 to 840 °C and 90 to 170 MPa corresponding to storage depths of ~ 4.0–6.5 km. Hornblende model T–P estimates coupled with in situ trace element fingerprinting imply that the magma bodies were individually well mixed, and not stratified. Compositional gaps between the three glass compositional types imply that no mixing between these magmas occurred. We interpret these data, coupled with the systematic changes in shard compositional proportions through the fall deposit, to reflect that three independent melt-dominant bodies of magma contributed large (A, ~ 270 km³), medium (B, ~ 90 km³) and small (C, ~ 40 km³) volumes (as reflected in the fall deposits) and were systematically tapped during the eruption. We propose that the systematic evacuation of the three independent magma bodies implies that there was tectonic triggering and linkage of eruptions. Our results show that supereruptions can be generated by near simultaneous multiple eruptions from independent magma chambers rather than the evacuation of a large single unitary magma chamber.     

Gravity waves in the mesopause region observed by meteor radar: 1. A simple measurement technique

A simple new technique for measuring gravity-wave activity using meteor radars is described. The technique uses the variance of horizontal wind velocities measured by individual meteors as a proxy for the activity of the gravity-wave field. It is sensitive to gravity waves with horizontal wavelengths of up to about 400 km and periods up to about 3 h. The technique can be used to investigate the vertical structure of the gravity-wave field at heights between approximately 80 and 100 km and with a time resolution of approximately 6 h. The technique is demonstrated using data from an all-sky meteor radar based at Rothera, Antarctica (68°S, 68°W). Observations made over Rothera for 2006 and 2007 reveal a seasonal behaviour with a semi-annual cycle in wave activity. Wave activity maximises in summer and winter and minimises at the equinoxes. Monthly mean gravity-wave activity increases with height in all seasons except in summer when gravity-wave variances show little or no increase with height below 90 km. Comparisons between the gravity-wave activity determined by this meteor-variance technique and other measurements at similar latitudes in the Antarctic reveal generally good agreement.     

Geoelectrical constraints on radar probing of shallow water-saturated zones within karstified carbonates in semi-arid environments

Shallow carbonates are of utmost importance as potential sources of groundwater in karstified semi-arid terrains. Ground-Penetrating Radar (GPR) is being increasingly used as a prominent mapping tool in such environments. However, its potential in exploring and identifying shallow water-saturated zones (WSZs) in carbonates is constrained by the geoelectrical properties of carbonate soils as a function of moisture content. We report results of a case study that includes laboratory geoelectrical characterization and their comparison to in situ GPR attenuation measurements performed on Cretaceous Edwards Formation rudist mounds in central Texas, which we hypothesize as analogs for water-bearing formations in semi-arid karstified carbonate terrains. Dielectric measurements on field-collected rock samples carried out in the laboratory under controlled conditions of moisture saturation suggest that real and imaginary parts of dielectric constants of rocks with higher porosity and/or permeability have steeper dependence on pore moisture content; they produce better dielectric contrasts but allow shallower penetration. Our analyses suggest that within carbonates, dielectric contrasts improve with decrease in sounding frequency and/or increase in moisture content; and the relationship between dielectric permittivity and moisture content may be represented by 3rd order polynomial equations. GPR surveys using a wide-band 400 MHz antenna reveal subsurface mound morphologies with heights of ～ 1–2 m and basal diameters of ～ 8–10 m resembling outcrop analogs. Each mound appears to be composed of smaller amalgamated lithounits that seem geoelectrically similar. Amplitudes decays of the backscattered radar signal correlate to moisture distribution. Measuring the differences in signal attenuation allows differentiation between saturated and non-saturated zones. Velocity analyses of GPR profiles enable estimation of moisture distribution in the vicinity of the mounds. Optimal delineation and production of high-resolution GPR data up to a depth of ～ 10 m were observed for a sounding frequency of ～ 250 MHz with moisture content of ～ 5% by weight. Below this moisture level, the dielectric contrast is insufficient to uniquely identify water-saturated zones from the surrounding geoelectrical context, and above it, the radar signal is substantially attenuated leading to a total inefficiency of the method.     

Optical dating of the upper 22 m of cored sediments from Daihai Lake,northern China

Daihai Lake is one of the largest lakes in the mid-latitude of northern China. Previous environmental change investigations using the sediments from the lake have been mainly focused on the last 13 ka. In 2006, we drilled an 80-m borehole on the southwest coast of the lake. Here we report the results of initial optical dating of the upper 22-m sediments from the core. Most of the samples allow separation of the 4–11 μm fine-grained and 45–63 μm medium-grained quartz, both of which were used for equivalent dose (D_e) determination. Dose recovery test experiments with the single-aliquot regeneration-dose (SAR) protocol indicate that a preheat at 240 °C for 10 s combined with a cut-heat of 240 °C is suitable for these samples. The D_e values show marked discrepancy between the two grain size fractions with the fine-grained quartz yielding up to over 50% higher D_e values than the medium ones for some samples. We consider the OSL ages for the samples from upper ～10 m to be overestimated. The main cause of the overestimation is attributed to the incomplete bleaching of the sediment grains at deposition. The OSL ages for the lower part of the sequence are considered to be reasonable age estimates which provide useful temporal constrains on the deposition of the sediments for the period of 20–40 ka.     

Model track studies on fouled ballast using ground penetrating radar and multichannel analysis of surface wave

Ballast fouling is created by the breakdown of aggregates or outside contamination by coal dust from coal trains, or from soil intrusion beneath rail track. Due to ballast fouling, the conditions of rail track can be deteriorated considerably depending on the type of fouling material and the degree of fouling. So far there is no comprehensive guideline available to identify the critical degree of fouling for different types of fouling materials. This paper presents the identification of degree of fouling and types of fouling using non-destructive testing, namely seismic surface-wave and ground penetrating radar (GPR) survey. To understand this, a model rail track with different degree of fouling has been constructed in Civil engineering laboratory, University of Wollongong, Australia. Shear wave velocity obtained from seismic survey has been employed to identify the degree of fouling and types of fouling material. It is found that shear wave velocity of fouled ballast increases initially, reaches optimum fouling point (OFP), and decreases when the fouling increases. The degree of fouling corresponding after which the shear wave velocity of fouled ballast will be smaller than that of clean ballast is called the critical fouling point (CFP). Ground penetrating radar with four different ground coupled antennas (500 MHz, 800 MHz, 1.6 GHz and 2.3 GHz) was also used to identify the ballast fouling condition. It is found that the 800 MHz ground coupled antenna gives a better signal in assessing the ballast fouling condition. Seismic survey is relatively slow when compared to GPR survey however it gives quantifiable results. In contrast, GPR survey is faster and better in estimating the depth of fouling.     

The Late Eocene 187Os / 188Os excursion: Chemostratigraphy,cosmic dust flux and the Early Oligocene glaciation

High resolution records (ca. 100 kyr) of Os isotope composition (¹⁸⁷Os / ¹⁸⁸Os) in bulk sediments from two tropical Pacific sites (ODP Sites 1218 and 1219) capture the complete Late Eocene ¹⁸⁷Os / ¹⁸⁸Os excursion and confirm that the Late Eocene ¹⁸⁷Os / ¹⁸⁸Os minimum, earlier reported by Ravizza and Peucker-Ehrenbrink [Earth Planet. Sci. Lett. 210 (2003) 151–165], is a global feature. Using the astronomically tuned age models available for these sites, it is suggested that the Late Eocene ¹⁸⁷Os / ¹⁸⁸Os minimum can be placed at 34.5 ± 0.1 Ma in the marine records. In addition, two other distinct features of the ¹⁸⁷Os / ¹⁸⁸Os excursion that are correlatable among sections are proposed as chemostratigraphic markers which can serve as age control points with a precision of ca. ± 0.1 Myr. We propose a speculative hypothesis that higher cosmic dust flux in the Late Eocene may have contributed to global cooling and Early Oligocene glaciation (Oi-1) by supplying bio-essential trace elements to the oceans and thereby resulting in higher ocean productivity, enhanced burial of organic carbon and draw down of atmospheric CO₂. To determine if the hypothesis that enhanced cosmic dust flux in the Late Eocene was a cause for the ¹⁸⁷Os / ¹⁸⁸Os excursion can be tested by using the paired bulk sediment and leachate Os isotope composition; ¹⁸⁷Os / ¹⁸⁸Os were also measured in sediment leachates. Results of analyses of leachates are inconsistent between the south Atlantic and the Pacific sites, and therefore do not yield a robust test of this hypothesis. Comparison of ¹⁸⁷Os / ¹⁸⁸Os records with high resolution benthic foraminiferal δ¹⁸O records across the Eocene–Oligocene transition suggests that ¹⁸⁷Os flux to the oceans decreased during cooling and ice growth leading to the Oi-1 glaciation, whereas subsequent decay of ice-sheets and deglacial weathering drove seawater ¹⁸⁷Os / ¹⁸⁸Os to higher values. Although the precise timing and magnitude of these changes in weathering fluxes and their effects on the marine ¹⁸⁷Os / ¹⁸⁸Os records are obscured by recovery from the Late Eocene ¹⁸⁷Os / ¹⁸⁸Os excursion, evidence of the global influence of glaciation on supply of Os to the ocean is robust as it has now been documented in both Pacific and Atlantic records.     

Using full-flash narrowband energy for ranging of lightning ground strokes

We demonstrate that narrowband measurements can be used for rudimentary ranging of cloud-to-ground lightning flashes. The system at present responds to both intra-cloud and cloud-to-ground lightning; ranging is demonstrated for a subset of flashes known to be cloud-to-ground lightning. The system uses a ferrite-core antenna with a length of about 4 cm and diameter 4 mm, and operates on a narrow band at about 1 MHz, close to the HF band (3–30 MHz). It downmixes the signal to audio frequencies and operates in a manner which is very similar to an AM radio. The system triggers on all impulses which exceed a given adjustable threshold above the ambient noise level, and records 1 s of data. Such a system was used to collect lightning-caused electromagnetic disturbances during summer 2006 in Finland. The output is compared to two scientifically verified references: a flat-plate broadband antenna measuring the vertical electric field and a commercial lightning location network giving flash location. A key aim of the system is to reduce the information to as few parameters as possible. Peak intensity and full-flash energy were used as simple parameters. It is shown that accurate flash-by-flash ranging is not possible with this method; however, it is shown that the method can be used to track clusters of ground flashes within a range of about 50–100 km with an accuracy of about 10 km.     

FeSi melting curve up to 70 GPa

The melting curve of iron monosilicide, FeSi, has been determined in a laser-heated diamond anvil cell from 6 up to 70 GPa by direct visual observation of the continuous laser-speckle motion in the liquid state. At 12 GPa and 1700 K, a discontinuous change in the slope of the melting curve indicates the first-order phase transition between the ?-FeSi (B20) and the CsCl-type FeSi structures (B2). During the phase transition the coordination number of both, Fe and Si atoms, increases from 7 to 8. Above this pressure, the melting curve rises steeply but shows significant flattening at higher pressures. A comparison with the melting curve of Fe shows that both curves cross at 32 ± 3 GPa, FeSi having higher melting temperatures (about 100 K) at high pressures.     

Velocity dispersion in fractured rocks in a wide frequency range

Experimental measurements of fracture-induced seismic waves velocity variations at frequencies ~ 1 kHz, ~ 40 kHz and ~ 1 MHz were performed directly in the field at the rocky outcrop and in the laboratory on specific rock samples collected from the outcrops. The peridotite–lherzolite outcrop appeared macroscopically uniform and contained three systems of visible parallel sub-vertical fractures. This rock has substantial bulk density and higher than average value of seismic wave velocity. The presence of fracture systems gives rise to its velocity anisotropy. The seismic waves passing through the rock fractures are subject to velocity dispersion and frequency dependent attenuation. Our data, obtained from field and laboratory measurements, were compared with theoretical model predictions. In this model we successfully used displacement discontinuity approach. For the velocity dispersion evaluation we used multi-frequency measurements. The a priori observation of orientations and densities of fracture sets allowed evaluation of their stiffness. Our approach revealed that the first arrivals of seismic waves can be used for evaluation of P-wave group velocities, the specific case, in which we expect anomalous velocity dispersion. Our observations contribute to the issue of up-scaling of well-log derived velocities in fractured rock to the scale of standard seismic exploration frequencies.