propagation characteristics of lg across the tibetan plateau abstract we present the results of a study on the propagation of lg within the tibetan plateau we analyze over 1200 seismograms for lg propagation from 185 local and regional earthquakes recorded at distances from 150 to 2000 km 52 of which are located within the tibetan plateau although the propagation of lg has been observed across most of asia lg has not been observed for paths crossing the tibetan plateau we analyze paths that cross the plateau boundaries and paths contained entirely within the tibetan plateau lg is generated within the tibetan plateau and can propagate to epicentral distances of at least 600 km for events located outside of the tibetan plateau lg is either absent or severely diminished for paths that cross both the himalayan and kunlun ranges confirming that the margins of the plateau weaken lg transmission based on the observations from our qualitative analysis we invert lg amplitudes for event station paths that are confined to the tibetan plateau to estimate the quality factor q the inversion yields a frequency dependent q function q f 366 37 f 0 45 0 06 0 5 f 16 h z similar observations in other areas indicate that frequency dependent apparent q within the tibetan plateau is well below that expected for a typical continental interior instead it has a frequency dependence that is characteristic of a tectonically active region

frequency dependent seismic attenuation in the eastern united states as observed from the 2011 central virginia earthquake and aftershock sequence abstract ground shaking due to earthquakes in the eastern united states eus is felt at significantly greater distances than in the western united states wus and for some earthquakes it has been shown to display a strong preferential direction shaking intensity variation can be due to propagation path effects source directivity and or site amplification in this paper we use s and lg waves recorded from the 2011 central virginia earthquake and aftershock sequence in the central virginia seismic zone to quantify attenuation as frequency dependent q f in support of observations based on shaking intensity we observe high q values in the eus relative to previous studies in the wus with especially efficient propagation along the structural trend of the appalachian mountains our analysis of q f quantifies the path effects of the northeast trending felt distribution previously inferred from the u s geological survey usgs did you feel it data historic intensity data and the asymmetrical distribution of rockfalls and landslides

frequency dependent lg q within the continental united states frequency dependent crustal attenuation 1 q is determined for seven distinct physiographic tectonic regions of the continental united states using high quality lg waveforms recorded on broadband stations in the frequency band 0 5 to 16 hz lg attenuation is determined from time domain amplitude measurements in one octave frequency bands centered on the frequencies 0 75 1 0 3 0 6 0 and 12 0 hz modeling errors are determined using a delete j jackknife resampling technique the frequency dependent quality factor is modeled in the form of q q 0 f regions were initially selected based on tectonic provinces but were eventually limited and adjusted to maximize ray path coverage in each area earthquake data was recorded on several different networks and constrained to events occurring within the crust m b 3 5 in size a singular value decomposition inversion technique was applied to the data to simultaneously solve for source and receiver terms along with q for each region at specific frequencies the lowest crustal q was observed in northern and southern california where q is described by the functions q 152 37 f 0 72 0 16 and q 105 26 f 0 67 0 16 respectively the basin and range province pacific northwest and rocky mountain states also display lower q and a strong frequency dependence characterized by the functions q 200 40 f 0 68 0 12 q 152 49 f 0 76 0 18 and q 166 37 f 0 61 0 14 respectively in contrast in the central and northeast united states q functions are q 640 225 f 0 344 0 22 and q 650 143 f 0 36 0 14 respectively show a high crustal q and a weaker frequency dependence these results improve upon previous lg modeling by subdividing the united states into smaller distinct tectonic regions and using significantly more data that provide improved constraints on frequency dependent attenuation and errors a detailed attenuation map of the continental united states can provide significant input into hazard map mitigation both scattering and intrinsic attenuation mechanisms are likely to play a comparable role in the frequency range considered in the study

mapping crustal heterogeneity using lg propagation efficiency throughout the middle east mediterranean southern europe and northern africa in this paper we describe a technique for mapping the lateral variation of lg characteristics such as lg blockage efficient lg propagation and regions of very high attenuation in the middle east north africa europe and the mediterranean regions lg is used in a variety of seismological applications from magnitude estimation to identification of nuclear explosions for monitoring compliance with the comprehensive nuclear test ban treaty ctbt these applications can give significantly biased results if the lg phase is reduced or blocked by discontinuous structure or thin crust mapping these structures using quantitative techniques for determining lg amplitude attenuation can break down when the phase is below background noise in such cases lg blockage and inefficient propagation zones are often mapped out by hand with our approach we attempt to visually simplify this information by imaging crustal structure anomalies that significantly diminish the amplitude of lg the visualization of such anomalies is achieved by defining a grid of cells that covers the entire region of interest we trace lg rays for each event station pair which is simply the great circle path and attribute to each cell a value equal to the maximum value of the lg p coda amplitude ratio for all paths traversing that particular cell the resulting map from this empirical approach is easily interpreted in terms of crustal structure and can successfully image small blockage features often missed by analysis of raypaths alone this map can then be used to screen out events with blocked lg prior to performing q tomography and to avoid using lg based methods of event identification for the ctbt in regions where they cannot work for this study we applied our technique to one of the most tectonically complex regions on the earth nearly 9000 earthquake station raypaths traversing the vast region comprised of the middle east mediterranean southern europe and northern africa have been analyzed we measured the amplitude of lg relative to the p coda and mapped the lateral variation of lg propagation efficiency with the relatively dense coverage provided by the numerous crossing paths we are able to map out the pattern of crustal heterogeneity that gives rise to the observed character of lg propagation we observe that the propagation characteristics of lg within the region of interest are very complicated but are readily correlated with the different tectonic environments within the region for example clear strong lg arrivals are observed for paths crossing the stable continental interiors of northern africa and the arabian shield in contrast weakened to absent lg is observed for paths crossing much of the middle east and lg is absent for paths traversing the mediterranean regions that block lg transmission within the middle east are very localized and include the caspian sea the iranian plateau and the red sea resolution is variable throughout the region and strongly depends on the distribution of seismicity and recording stations lg propagation is best resolved within the middle east where regions of crustal heterogeneity on the order of 100 km are imaged e g south caspian sea and red sea crustal heterogeneity is resolvable but is poorest in seismically quiescent northern africa

attenuation of multiphase surface waves in the basin and range province part i lg and lg coda summary broad band data recorded by the lawrence livermore laboratory network are used to investigate whether or not lg q and lg coda q have similar values in the basin and range province of north america in order to retrieve spectral estimates of the broad band lg and lg coda signals a hybrid method is used which retains high fidelity at lower frequencies while strongly smoothing the spectral estimates and minimizing the number of spectral points at high frequencies a stochastic approach is used to model the lg signal and ambient noise and to analyse results from two station determinations of lg q in the basin and range the effects of ambient noise frequency dependent station site response and focusing defocusing on lg q inversion are analysed it is shown that after averaging spectral ratios determined from repeated observations over four two station paths a modest site effect will not cause significant errors in the resulting lg q relation using this inversion scheme and spectral ratio estimates averaged over those paths at frequencies between 0 2 and 2 5 hz we obtain the relation qlg f 267 f 56 f0 37 0 06 for the basin and range province further constraints on lg q were obtained from lg coda which due to the natural averaging effect of scattering is insensitive to effects of focusing defocusing to investigate the validity of the single isotropic scattering model for lg coda in the basin and range province we calculated ischrons for scatterers corresponding to later lg coda signals as required by the single scattering model it is found that when significant portions of these isochrons are oceanic lg coda amplitude decay becomes irregular and abnormally slow suggesting a strong scattering reflection effect caused by the rapidly changing crustal structure along the coast applying the single isotropic scattering model to lg coda records with isochrons mostly confined to the continental crust results in q f 275 f 26 f 0 36 0 03 which is nearly identical to our qlg relation this indicates that even in a complicated geological province a joint interpretation of the dynamic properties of lg and lg coda can be successful and fruitful inconsistent lg q and coda q relations found in earlier studies in the basin and range province may be attributed to different settings of parameter trade offs different seismic phases or different dynamic properties being used

simulation of earthquake ground motions in the eastern united states using deterministic physics based and site based stochastic approaches abstract earthquake ground motion recordings are scarce in the central and eastern united states ceus for large magnitude events and at close distances we use two different simulation approaches a deterministic physics based method and a site based stochastic method to simulate ground motions over a wide range of magnitudes drawing on previous results for the modeling of recordings from the 2011 m w 5 8 mineral virginia earthquake and using the 2001 m w 7 6 bhuj india earthquake as a tectonic analog for a large magnitude ceus event we are able to calibrate the two simulation methods over this magnitude range both models show a good fit to the mineral and bhuj observations from 0 1 to 10 hz model parameters are then adjusted to obtain simulations for m w 6 5 7 0 and 7 6 events in the ceus our simulations are compared with the 2014 u s geological survey weighted combination of existing ground motion prediction equations in the ceus the physics based simulations show comparable response spectral amplitudes and a fairly similar attenuation with distance the site based stochastic simulations suggest a slightly faster attenuation of the response spectral amplitudes with distance for larger magnitude events and as a result slightly lower amplitudes at distances greater than 200 km both models are plausible alternatives and given the few available data points in the ceus can be used to represent the epistemic uncertainty in modeling of postulated ceus large magnitude events

the shape of ground motion attenuation curves in southeastern canada the shape of the attenuation curve of the fourier spectrum of acceleration is established for southeastern canada from empirical data the dataset is comprised of 1200 digital vertical component seismograms from 100 earthquakes recorded on 30 stations of the eastern canada telemetered network the distance range of the observations is 10 to 1700 km focal depths are from 5 to 30 km results indicate that the attenuation curve has three distinct sections at distances less than 70 km corresponding to attenuation of the direct wave amplitudes decay slightly more rapidly than 1 r r 1 1 between 70 and 130 km where the direct wave is joined by sms spectral amplitudes are approximately constant beyond 130 km corresponding to the lg phase amplitudes decay at a rate that is consistent with r 0 5 and q 670 f 0 33 the findings support the hypothesis of burger et al 1987 that postcritical reflections from the moho discontinuity play an important role in determining the shape of the attenuation curve however the influence of sms is subtle allowing the shape to be approximated by simple functional forms for example the commonly assumed bilinear form r 1 r 0 5 with frequency dependent q fits well if the transition from direct wave to lg spreading is placed at approximately 60 km a linear form r 1 over all distances with constant q 2000 also provides a satisfactory fit overall we find little evidence for the dependence of attenuation on focal depth or tectonic province

soil morphology genesis and monolith construction of an acid sulfate soil with silica cementation in the us mid atlantic region abstract soil monoliths are powerful tools for soil education and for representing soils as they are found in the field they preserve and display major soil features and are portable the monolith herein described was collected from an active acid sulfate soil located near the western shore of the chesapeake bay in the coastal plain physiographic province in maryland us the key features of this profile include a silica cemented layer a sulfuric horizon prominent concentrations of jarosite and iron oxide glauconite and sulfidic materials the silica cemented layer similar to a duripan created a challenge for the collection of a soil monolith from this site this layer was disassembled fragments were cut to size and the layer was reassembled in a soil monolith containing the underlying and overlying soil horizons this appears to be the first published report of a method for creating a soil monolith in a silica cemented soil silica cementation in acid sulfate soils is rarely reported in the pedologic literature though cemented layers are occasionally reported in literature on sulfidic mine tailings by understanding silica cementation in acid sulfate soils we may be able to induce it as a management practice in mine tailings and other environmentally hazardous sites the goals of this study are to report on a method for creating soil monoliths from silica cemented soils to present explanations for the genesis of this unusual soil and to highlight how a pedologic study of this soil could lead to further experiments to mitigate some environmentally hazardous sites

lateral variation of pn and lg attenuation at the cdsn station lsa abstract the propagation efficiencies of the regional phases lg and pn are indicative of how active and recent tectonics influence crust and uppermost mantle properties respectively in this study regional scale lateral heterogeneity of lg and pn attenuation for the region in and around the southern tibetan plateau is investigated the data set is comprised of seismograms recorded at the chinese digital seismogram network cdsn station lsa from regional events with epicentral distances within 11 attenuation of lg and pn is calculated using spectral methods and assuming constant q lg and q pn models for the frequency bands 0 3 to 3 0 hz and 0 5 to 4 0 hz respectively lateral variation in attenuation is estimated by analyzing data on an event by event basis significant lateral variation is observed with q lg decreasing from about 520 for events south of lsa to about 340 for events north of lsa and q pn 670 for southern backazimuths while q pn 240 for northern events for pn this north south variation is consistent with other observations indicating partially melted upper mantle beneath north central tibet for lg the azimuthal variation in attenuation indicates that lg propagation as observed at lsa is efficient for paths crossing the southern boundary of the tibetan plateau relative to paths within the plateau itself

evaluation of nga west2 and chinese ground motion prediction equations for developing seismic hazard maps of mainland chinaevaluation of nga west2 and chinese gmpes for developing seismic hazard maps of mainland china

three dimensional compressional wave attenuation tomography for the crust and uppermost mantle of northern and central california i present a frequency independent three dimensional 3 d compressional wave attenuation model indicated by quality factor qp for the crust and uppermost mantle of northern and central california the tomographic inversion used t values measured from amplitude spectra of 80 988 p wave arrivals of 3247 events recorded by 463 network stations through a 3 d seismic velocity model the model has a uniform horizontal grid spacing of 15 km and the vertical node intervals range between 2 and 10 km down to 45 km depth in general the resulting qp values increase with depth and agree with the surface geology at shallow depth layers the most significant features observed in the qp model are the high qp values in the sierra nevada mountains and low qp anomalies in the western fault zones low qp values are also imaged in owens valley and long valley at shallow depths and the cape mendocino region in the lower crust 25 km depth an overall contrast of qp values across the fault is observed in the creeping parkfield and cholame carrizo sections of the san andreas fault the new 3 d qp model provides an important complement to the existing regional scale velocity models for interpreting structural heterogeneity and fluid saturation of rocks in the study area

attenuation of high frequency shear waves in the crust measurements from new york state south africa and southern california we compare the attenuation of high frequency 3 30 hz shear waves for crustal paths in new york state south africa and southern california over source receiver distances of about 10 400 km the data consist of digital recordings of s waves 5 100 km and lg waves 100 400 km produced by earthquakes we use a coda normalization method to remove the effects of site amplification and source excitation from the amplitudes of the s and lg waves over the entire distance range studied 10 400 km the amplitude decay of 3 hz shear wave energy is considerably less for the tectonicaily stable areas of new york and south africa than for the tectonicaily active region of southern california high frequency 30 hz s wave attenuation is significantly less for new york and south africa than for southern california for distances between 15 and 90 km we parameterize the decay with distance r of coda normalized shear wave amplitudes with a frequency independent q and geometrical spreading exponent where geometrical spreading is proportional to r for new york state the s wave amplitude decay 3 30 hz is well described by a frequency independent q of 2100 330 490 and of 1 3 0 1 the decay of lg wave amplitudes from 3 to 15 hz in the new york state region is fit with a frequency independent q of 1600 280 330 of 0 70 0 2 the s wave amplitudes 3 30hz in south africa yield a q of 1500 190 380 and of 1 3 0 1 fixing the geometrical spreading at r 0 5 produces an lg wave q estimate at 3 hz in south africa of 360 50 80 this lg wave q is low considering that south africa is a cratonic tectonicaily stable area the s wave amplitudes from southern california are described with a frequency independent q of 800 150 240 and a large geometrical spreading exponent of of 1 9 0 2 we find an lg wave q at 3 hz of 260 30 for southern california after constraining the geometrical spreading at r 0 5

a comprehensive pollen and tephra based chronostratigraphic model for the late glacial and holocene period in the french massif central this paper discusses about 250 conventional c 14 ages obtained on peat and gyttja samples that apply to pollen features or tephra beds in the massif central region of france a method to estimate the migration periods of eight late glacial to holocene pollen features typical of the massif central is described a review of all c 14 ages pertaining to tephras of this region enabled the most appropriate age or age range of the tephras to be estimated the chronostratigraphic relationships between pollen features and tephras are discussed and a new comprehensive stratigraphic model is presented the model shows that pollen features are diachronous and should not be used therefore as proxy stratigraphic markers copyright c 1996 inqua elsevier science ltd

average attenuation of 0 7 5 0 hz lg waves and magnitude scale determination for the region bounding the western branch of the east african rift summary the investigation of lg attenuation characteristics in the region bounding the western branch of the east african rift system using digital recordings from a seismic network located along the rift between lake rukwa and lake malawi is reported a set of 24 recordings of lg waves from 12 regional earthquakes has been used for the determination of anelastic attenuation q lg and regional body wave magnitude m blg scale the events used have body wave magnitudes m b between 4 6 and 5 5 which have been determined teleseismically and listed in isc bulletins the data were timedomain displacement amplitudes measured at 10 diverent frequencies 0 7 5 0 hz q lg and its frequency dependence g in the region can be represented in the form q lg 186 2 6 5 f 0 78 0 05 this model is in agreement with models established in other active tectonic regions the lg wave based magnitude formula for the region is given by m blg log a 3 76 0 38 log d 5 72 1 06 where a is a half peak topeak maximum amplitude of the 1 s lg wave amplitude in microns and d is the epicentral distance in kilometres magnitude results for the 12 regional earthquakes tested are in good agreement with the isc body wave magnitude scale

measurement of frequency dependent lg attenuation in the great basin measurement of the spatial decay of spectral amplitudes of the higher mode seismic surface wave train lg indicates that in the great basin the apparent seismic quality factor q is a function of frequency observations along a 300 km profile recording of a nuclear explosion yield the function q 206 0 68 over the band 0 3 10 0 hz similar analysis using numerous recordings of earthquakes along paths which provide a good average sampling of the great basin crust gives q 214 15 0 54 0 09 for 0 3 5 0 hz if the crustal sampling by lg energy from nuclear explosions surface sources is primarily in the shallow crust as has been suggested then these results indicate a greater frequency dependence of apparent q there than at depth

summary of the gk15 ground motion prediction equation for horizontal pga and 5 damped psa from shallow crustal continental earthquakes we present a revised ground motion prediction equation gmpe for computing medians and standard deviations of peak ground acceleration pga and 5 damped pseudospectral acceleration psa response ordinates of the horizontal component of randomly oriented ground motions to be used for seismic hazard analyses and engineering applications this gmpe is derived from the expanded next generation attenuation nga west 1 database see data and resources 1 chiou et al 2008 the revised model includes an anelastic attenuation term as a function of quality factor q to capture regional differences in far source beyond 150 km attenuation and a new frequency dependent sedimentary basin scaling term as a function of depth to the 1 5 km s shear wave velocity isosurface to improve ground motion predictions at sites located on deep sedimentary basins the new graizer kalkan 2015 gk15 model developed to be simple is applicable for the western united states and other similar shallow crustal continental regions in active tectonic environments for earthquakes with moment magnitudes m 5 0 8 0 distances 0 250 km average shear wave velocities in the upper 30 m v s 30 200 1300 m s and spectral periods t 0 01 5 s our aleatory variability model captures interevent between event variability which decreases with magnitude and increases with distance the mixed effect residuals analysis reveals that the gk15 has no trend with respect to the independent predictor parameters compared to our 2007 2009 gmpe the pga values are very similar whereas spectral ordinates predicted are larger at t 0 2 s and they are smaller at longer periods 1 sec 21

regionalization of crustal coda q in the continental united states a contour map of crustal q sub 0 values for the entire united states is presented based on a scattering model to explain the coda waves of local and near regional earthquakes these coda q sub 0 values are in good agreement with q of lg waves data are obtained from over 250 local earthquakes with most magnitudes between 3 0 and 5 0 recorded by 25 wwssn and 27 lrsm stations throughout the continental united states these two sets of data provide a range of frequencies from 0 5 to 3 5 hz a frequency dependence of q is observed in the range of frequencies considered a power law dependence of the form q q sub 0 f f sub 0 sup eta is assumed the value of frequency dependence eta is found to be maximum in the tectonically active western united states and least in the stable regions of the central and south central united states the lowest q sub 0 values are obtained in the western united states with values ranging from 140 to 200 in the coastal plains average crustal q sub 0 values for the basin and range province vary from 200 to 300 increasing gradually to 400 in the colorado plateau region q sub 0 valuesmore in the columbia plateau vary from 200 to 400 q sub 0 values increase very rapidly along the central and southern rocky mountains from 400 to 800 east of the rocky mountains q sub 0 values increase gradually in the interior plains to a maximum value of around 1300 in the mississippi embayment region farther east q sub 0 values decrease gradually to an almost constant value of 1000 along the appalachian mountains coastal regions of eastern and northeastern united states have a crustal q sub 0 value between 900 to 700 regions of north central and gulf coastal plains show low q sub 0 values ranging from 600 to 400 and less the source factor b f sub p a measure of the intensity of scattering was obtained for several different regions of the continental united states regions of high q sub 0 values exhibit low intensity of scattering less

mechanisms of seismic attenuation in the crust scattering and anelasticity in new york state south africa and southern california the envelopes of high frequency seismograms from earthquakes in new york state south africa and southern california are analyzed to determine how much of the observed attenuation of shear waves in the crust is caused by anelasticity and how much is produced by scattering from small scale heterogeneities for seismograms from new york and south africa there is a systematic enrichment of high frequency energy that develops in the coda relative to the direct s or l sub g waves the author uses the growth with source receiver distance of the high frequency energy in the coda relative to the direct wave to estimate the scattering attenuation of the crust and the relative time decay of high frequency energy in the coda to determine the anelastic attenuation using the estimate of l sub g wave q as a constraint he finds that the scattering q in the crust of new york is either independent of frequency or increases with frequency f slower than f sup 0 3 a similar analysis for south africa indicates that scattering is the major cause of the observed s wave attenuation of high frequency energy 30 hz at local distances 100 km for southern california the extent of the scattering attenuation is unclear from the data more although the relatively steep coda decay of southern california implies that anelastic attenuation is stronger there than in new york or south africa for southern california and new york state the 3 hz coda q taken from the late coda 50 110 s is comparable to the l sub g wave q however the 3 hz coda q for south africa over these lapse times is about 5 times the estimated l sub g wave q for all three areas the frequency dependence of the coda q does not match the frequency dependence of the s wave q and for new york and south africa it changes with lapse time less

lg wave propagation and crustal structure differences near denmark and the north sea summary recordings of regional earthquakes near denmark and the north sea have been collected in an attempt to find the lg wave propagation properties in the area propagation paths of lengths between 300 and 1100km are investigated the amplitudes of the lg waves and the other seismic phases in the seismograms are compared the propagation paths are classified according to whether the lg wave propagation compared to p and s wave propagation is good intermediate or poor it is noted that there is a distinct regional pattern in the lg wave attenuation the lg wave propagation is poor across the north sea the north sea is surrounded by areas of good continental lg wave propagation except towards the south east in the netherlands and western germany an area in skagerrak is characterized by good but slow propagation of a surface wave similar to lg since this is exactly the area of a cluster of earthquakes in skagerrak it is suggested that the two phenomena are caused by the same structural inhomogeneities in the area just off the coast of north western denmark the lg wave propagation is as good in the northern part of denmark as it is in the fennoscandian shield the extent to which the propagation is poor across the north sea is dependent on the frequency of the lg waves observed with different seismographs the lg waves are more attenuated relative to the other seismic phases the higher the frequency is between 0 25 and 2 hz as the structural differences between the fennoscandian bedrock area and the norwegian danish basin with 8 10 km of sediments has no effect on the lg wave propagation it is suggested that the structural anomalies causing the poor lg wave propagation across the north sea are deep crustal anomalies possibly significant variations in crustal thickness it is likely that such deep crustal differences are located along the most prominent upper crustal differences in the sedimentary grabens in the middle of the north sea the poor propagation across the north sea is similar to that observed across a sedimentary basin in eastern greenland which also developed mainly before seafloor spreading separated greenland from europe the frequency dependent propagation of the lg waves is explainable in terms of surface wave propagation across structural boundaries as well as in terms of anelastic attenuation

variability of crustal attenuation in the northeastern united states from lg waves high quality digital seismograms from eight pairs of collocated earthquakes in the northeastern united states were analyzed to determine accurate source spectrum corner frequencies this was accomplished by applying the empirical green s function method to regional pg and lg or sg phases recorded by vertical component seismographs of the u s national seismographic network usnsn and the lamont doherty cooperative seismographic network lcsn stations the frequency band used was 0 5 16 hz for usnsn and 1 30 hz for lcsn records the source spectrum corner frequencies for the eight larger earthquakes of the event pairs magnitudes between mb lg 2 5 4 1 range from about 4 3 to 16 3 hz based on the comer frequencies obtained independently from the empirical green s function analysis sg or lg wave displacement amplitude spectra up to 30 hz were used to determine the crustal average q factors along 87 event station paths these paths crossed diverse tectonic features in the northeastern united states and were in the epicentral distance range of 41 to 1394 km we found that within the northeastern united states the crustal average qlg we obtained was frequency dependent and showed spatial variability which correlated fairly well with the major tectonic features in the region our attenuation measurements indicated low lg attenuation in the adirondack mountains with exposed precambrian grenville basement with qlg 905 f0 40 high lg attenuation in the central appalachian province with qlg 561 586 f0 46 0 47 and an intermediate lg attenuation in northern new england appalachians with q 705 f0 41