a comparison of modeling approaches for steady state unconfined flow abstract the dupuit forchheimer the fully saturated flow and the variably saturated flow models are compared for problems involving steady state unconfined flow through porous media the variably saturated flow model is the most comprehensive of the three and requires more parameters the performances of the three models are compared for different soil properties problem dimensions and flow geometries there are certain types of problems where the simpler models may yield satisfactory results for soils with large pores and or broad pore size density functions the variably saturated flow model solutions to steady state problems approach those of the fully flow model owing to the manner in which the soil water retention curve and relative permeability function respectively affect the variably saturated flow model solutions for problems of significant size the fully saturated flow model may be sufficient as the effects of the vadose zone are relatively diminished for problems with radial symmetry e g steady flow to a well the fully saturated flow model performs well because the variably saturated flow model is relatively insensitive to the parameters describing the soil properties as the amount of vadose zone flow compared with the total flow is relatively insignificant in such problems

aftershock sequence of the 1994 mw 6 8 liwa earthquake indonesia seismic rupture process in a volcanic arc we present the aftershock activity following the february 15 1994 mw 6 8 earthquake which was strongly felt in southern sumatra indonesia near the great sumatran fault gsf at this place the slip rate is supposed to be low neverthless three m 6 events occurred along this segment during this century no significant instrumental microseismicity has ever been recorded there we use data from both the regional indonesian network and a local seismic array operating 11 days after the mainshock during one month aftershocks mostly locate in a broad zone of 55 20 km near two active nw trending strike slip segments of the gsf separated by a recent caldera suwoh during the experiment the nw segment from suwoh up to 15 km se of the ranau lake caldera an old right stepover pull apart was very active as first suggested by the aftershock distribution and the lack of coseismic rupture at the surface the 20 focal mechanisms determined provide evidence for various post seismic stress adjustments on secondary faults located in the ranau suwoh paleo pull apart graben less than 20 of the aftershocks are directly linked to the main rupture a nearly pure right lateral strike slip faulting reaching 25 km depth a narrow seismic gap underlines the active volcanic area of suwoh we conclude that the rupture process along the gsf is controlled both by volcanism and structures and that the volcanic activity affects the mechanical properties of the crust only in a narrow zone

earthquake history of the sumatran fault indonesia since 1892 derived from relocation of large earthquakes abstract we map the fault planes of m 7 0 earthquakes along the sumatran fault in sumatra western indonesia for the period since 1892 to obtain precise hypocenter locations of large earthquakes and identify fault planes of m 7 0 earthquakes we relocated 27 m 6 0 earthquakes from 1921 to 2012 using the modified joint hypocenter determination method we found that six m 7 0 events appear to have occurred on segments of the sumatran fault as follows kumering for the 1933 m s 7 5 event the northwestern and southeastern parts of tripa for the 1935 m s 7 0 and 1936 m s 7 2 events respectively the southeastern half of sunda for the april 1943 m s 7 1 event ketaun for the first m s 7 3 event of the june 1943 doublet and suliti and sumani for the second m s 7 6 event of the june 1943 doublet we also identified the faults of four m 7 0 earthquakes between 1892 and 1920 by using information on crustal deformation and damage distributions from the results of earthquake locations between 1892 and 2012 and the corresponding fault lengths of m 7 0 earthquakes we have interpreted the large m 7 0 earthquake history of the sumatran fault for the past 120 years possible seismic gaps for m 7 0 earthquakes along the sumatran fault are the northern half of the sunda segment and the semangko dikit sianok barumun toru renun aceh and seulimeum segments

three dimensional p wave velocity structure beneath the indonesian region abstract we present the p wave seismic tomography image of the mantle to a depth of 1200 km beneath the indonesian region the artb inversion method is applied to a dataset of 118 203 p wave travel times of local and teleseismic events taken from isc bulletins although the resolution is sufficient for detailed discussion in only a limited part of the study region the results clarify the general tectonic framework in this region and indicate a possible remnant seismic slab in the lower mantle structures beneath the philippine islands and the molucca sea region are well resolved and high velocity zones corresponding to the slabs of the molucca sea and philippine sea plates are well delineated seismic zones beneath the manila negros and cotabato trenches are characterized by high velocity anomalies although shallow structures were not resolved the molucca sea collision zone and volcanic zones of the sangihe and philippine arcs are dominated by low velocity anomalies the philippine sea slab subducts beneath the philippine islands at least to a depth of 200 km and may reach depths of 450 km the southern end of the slab extends at least to about 6 n near southern mindanao in the south the two opposing subducting slabs of the molucca sea plate are clearly defined by the two opposing high velocity zones the eastward dipping slab can be traced about 400 km beneath the halmahera arc and may extend as far north as about 5 n unfortunately resolution is not sufficient to reveal detailed structures at the boundary region between the halmahera and philippine sea slabs the westward dipping slab may subduct to the lower mantle although its extent at depth is not well resolved this slab trends n s from about 10 n in the philippine islands to northern sulawesi a ne sw trending high velocity zone is found in the lower mantle beneath the molucca sea region this high velocity zone may represent a remnant of the former subduction zone which formed the sulawesi arc during the miocene the blocks along the sunda and banda arcs are less well resolved than those in the philippine islands and the molucca sea region nevertheless overall structures can be inferred the bowl shaped distribution of the seismicity of the banda arc is clearly defined by a horseshoe shaped high velocity zone the tomographic image shows that the indian oceanic slab subducts to a depth deeper than 300 km i e deeper than its seismicity beneath andaman islands and sumatra and may be discontinuous in northern sumatra along southern sumatra java and the islands to the east the slab appears to be continuous and can be traced down to at least a depth of the deepest seismicity where it appears to penetrate into the lower mantle

the capillary fringe and its effect on water table response abstract shallow water tables are often observed to respond in a highly disproportionate manner to precipitation events that is the magnitude of the response is often much greater than would be predicted on the basis of the specific yield of the geologic material and the amount of rainfall physical arguments are presented to show that if the capillary fringe the zone of tension saturation extends to ground surface then the addition of a very small amount of water can result in an immediate and large rise in the water table the arguments are supported by a field experiment in which the addition of 0 3 cm of water caused the water table to rise 30 cm in 0 25 min thus demonstrating the large and highly transient influence of the capillary fringe on the position of the water table the evidence in this study as well as recent work of others suggests that the capillary fringe effect could have a major influence on the process of stream flow generation contaminant transport to surface waters and contaminant transport in hydrogeologic regimes having shallow water tables it is further shown that calculations of groundwater recharge and consumptive use based on water table response and an assumed specific yield could be substantially in error

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

one century of tectonic deformation along the sumatran fault from triangulation and global positioning system surveys an analysis combining historical triangulation and recent global positioning system gps survey measurements in west and north sumatra indonesia reveals a detailed slip history along the central part of the sumatran fault the arc parallel components of the combined velocity field are consistent with slip rates inferred from gps data ranging from 23 to 24 mm yr between 1 0 s and 1 3 n the sumatran fault appears to be characterized by deep locking depths of the order of 20 km and the occurrence of large mw 7 earthquakes the long term 1883 1993 strains show simple right lateral shear with rates similar to gps measured 1989 1993 strain rates coseismic deformation due to the 1892 tapanuli and 1926 padang panjang earthquakes estimated from triangulation measurements taken before and after the events indicates that the main shocks were significantly larger than previously reported the 1892 earthquake had a likely magnitude of mw 7 6 while the 1926 events appear to be comparable in size to the subsequent m 7 1943 events and an order of magnitude higher than previously reported

revision of magnitudes of large shallow earthquakes 1897 1912 abstract in previous research trace amplitudes of surface wave maxima recorded by undamped milne seismographs were used to determine the surface wave magnitudes ms of large shallow earthquakes which occurred prior to 1912 for this purpose the effective gain of these instruments was calibrated by using the surface wave magnitudes ms gr which were calculated from the unpublished worksheets for seismicity of the earth of gutenberg and richter in this paper the real quality of ms gr is critically re evaluated by using independent sets of data it is found that ms gr for the period 1904 1909 is considerably overestimated the average excess from the real ms is 0 5 units for 1904 1906 0 4 for 1907 0 3 for 1908 1909 and 0 0 for 1910 1912 this overestimation is so systematic and large that the previous results are all redetermined the average effective gain of milne instruments is revised to be 21 9 previously the gain depended on ms this revision results in systematic reduction in the previously assigned magnitudes the revised values of ms for 264 shallow earthquakes with ms 6 8 and over in the period 1897 1912 inclusive are listed the present revision is large enough to preclude the possibility of the high activity of large shallow earthquakes around the turn of the century the present results have a direct effect on all the magnitude catalogues of shallow earthquakes which occurred prior to 1909

steady state analysis of unsaturated flow above a shallow water table aquifer drained by ditches the one dimensional pressure head profile above a fixed water table was studied for different steady infiltration rates as shown in previous studies when the infiltration rate qin is less than the soil saturated hydraulic conductivity ks this profile can be divided into two parts 1 from the water table surface z0 to an elevation z the pressure head varies from 0 to a value h such as k h qin 2 above the elevation z the pressure head is constant and equal to h above the water table the zone where the pressure head is variable has been called transition zone its height is shown to be highly variable and to depend on soil properties as well as on the infiltration rate this transition zone is not the capillary fringe as defined by gillham gillham r w 1984 the capillary fringe and its effect on water table response j hydrol 67 307 324 numerical experiments performed with hydrus 2d for the case of a water table drained by parallel ditches have shown that the height of the transition zone is similar in the one dimensional profile and in the two dimensional system as long as the local slope of the water table is small this result is important since in a two dimensional system the transition zone is the place where all the horizontal component of the unsaturated flow occurs the ratio of the horizontal component of the unsaturated flow vs the total horizontal flow in both the unsaturated and saturated zones has been computed for a given soil this ratio decreases as the infiltration rate increases for a given infiltration rate the soil with the thinnest transition zone transfers the largest amount of water above the water table

an examination of computed steady state water table heights in unconfined aquifers dupuit forchheimer estimates and exact analytical results abstract the precision with which water table heights are given by the dupuit forchheimer analysis is examined by comparing calculated water table heights with those obtained by exact solution of laplace s equation for boundary conditions that are approximately the same in both cases the dupuit forchheimer solutions for flow through a vertically sided earth bank with no tail water and for drainage to parallel ditches sunk to a horizontal impermeable floor approximate to that given by kozeny s parabola solution for groundwater flow to a horizontal toe drain and to that given by engelund s solution for drainage of uniform rainfall to horizontal drains respectively except in the vicinity of the drains in both situations the water table height given by the analytical solutions immediately above the beginning of the horizontal drains is a good estimate of the height of the seepage surface that the dupuit forchheimer analysis ignores it is argued that the dupuit forchheimer analysis gives water table heights closer to the true values when there is tail water when water seeps from ditches to feed evaporation from the soil surface there is no seepage surface and the dupuit forchheimer water table prediction is not very different from the true value for soils with hydraulic conductivity varying with height the girinsky potential allows water table heights to be calculated making use of the dupuit forchheimer assumption and gives more accurate estimates when the hydraulic conductivity increases with height

source model of an earthquake doublet that occurred in a pull apart basin along the sumatran fault indonesia summary on 2007 march 6 an earthquake doublet occurred along the sumatran fault indonesia the epicentres were located near padang panjang central sumatra indonesia the first earthquake with a moment magnitude m w of 6 4 occurred at 03 49 utc and was followed two hours later 05 49 utc by an earthquake of similar size m w 6 3 we studied the earthquake doublet by a waveform inversion analysis using data from a broadband seismograph network in indonesia jisnet the focal mechanisms of the two earthquakes indicate almost identical rightlateral strike slip faults consistent with the geometry of the sumatran fault both earthquakes nucleated below the northern end of lake singkarak which is in a pull apart basin between the sumani and sianok segments of the sumatran fault system but the earthquakes ruptured different fault segments the first earthquake occurred along the southern sumani segment and its rupture propagated southeastward whereas the second one ruptured the northern sianok segment northwestward along these fault segments earthquake doublets in which the two adjacent fault segments rupture one after the other have occurred repeatedly we investigated the state of stress at a segment boundary of a fault system based on the coulomb stress changes the stress on faults increases during interseismic periods and is released by faulting at a segment boundary on the other hand the stress increases both interseismically and coseismically and may not be released unless new fractures are created accordingly ruptures may tend to initiate at a pull apart basin when an earthquake occurs on one of the fault segments the stress increases coseismically around the basin the stress changes caused by that earthquake may trigger a rupture on the other segment after a short time interval we also examined the mechanism of the delayed rupture based on a theory of a fluidsaturated poroelastic medium and dynamic rupture simulations incorporating a rheological velocity hardening effect these models of the delayed rupture can qualitatively explain the observations but further studies especially based on the rheological effect are required for quantitative studies

magnitudes of large shallow earthquakes from 1904 to 1980 abstract in order to obtain a uniform magnitude catalogue surface wave magnitudes ms and broad band body wave magnitudes mb have been determined for large shallow earthquakes from 1904 to 1980 in making the catalogue homogeneous the author consistently adheres to the original definitions of ms and mb given by gutenberg 1945 and gutenberg and richter 1956 the determinations of ms and mb are all based on the amplitude and period data listed in gutenberg and richter s unpublished notes bulletins from stations worldwide and other basic information mb is measured on broad band instruments in periods of 8 s consistency of the magnitude determinations from these different sources is carefully checked in detail more than 900 shallow shocks of magnitude 7 and over are catalogued the meaning of the magnitude scales in various catalogues is examined in terms of ms and mb most of the magnitudes listed by gutenberg and richter 1954 in their seismicity of the earth are basically ms for large shocks shallower than 40 km but are basically mb for large shocks at depths of 40 60 km the surface wave magnitudes given by earthquake data reports are higher than ms by 0 2 unit whether the combined horizontal amplitude or the vertical amplitude is used mb and the currently used 1 s body wave magnitude are measured at different periods and should not be directly compared

distribution of slip at the northern sumatran fault system we model spatial variations in horizontal displacements of 117 geodetic sites measured during annual surveys in 1989 1996 with the global positioning system gps as elastic strain across a locked strike slip fault to infer the contemporary slip rate locking depth and location of the sumatran fault sf in northern sumatra 1 s 3 n gps derived slip rate estimates increase slightly northward from 23 plus or minus 3 mm yr at 0 8 deg s to 26 plus or minus 2mm yr at 2 7 n they agree with geologic estimates north of the equator but at 0 5 s they are about 10 mm yr higher strain appears to be distributed asymmetrically about the fault south of 2 n about 5 mm yr of shear is required within the offshore forearc west of the fault to achieve a closer agreement of fault locations inferred from gps velocities with geologically identified traces of the sf locking depth estimates are on the order of 10 20 km the western branch of the major fault bifurcation near 1 n slips at a rate five times higher than the eastern branch the two main strands of the fault at the northwestern tip of sumatra 5 5 n appear to be nearly free of horizontal strain significant slip must occur away from the two strands probably further east at two other geologically active branches the banda aceh embayment is extruded to the northwest at a rate of 5 plus or minus 2 mm yr within the estimated velocity uncertainties of several mm yr fault normal deformation along the sf is insignificant almost strain free the northern part of the back arc basin is part of a rigid sunda shelf while the northern forearc is subjected to 8 plus or minus 5 x 10 exp 8 yr of extension nearly parallel to the arc

whole mantle p wave travel time tomography abstract a method of tomographic inversion to obtain three dimensional velocity perturbations in the earth s whole mantle has been developed and applied to more than two million p wave arrival time data reported by international seismology center isc the model is parameterized with 32 768 blocks the divisions in latitude longitude and radius are 32 64 and 16 respectively horizontal cell size is 5 6 5 6 the layer thicknesses vary with depth 29 km just below the surface and 334 km just above the core mantle boundary starting from a spherically symmetric earth model we obtained a three dimensional model using the following iterative procedures first we relocated all the events second we backprojected the residual into the whole mantle third we refined the spherically symmetric earth model the solutions have been converged in five iterations we adopted the following techniques in the backprojection procedure the first order smoothness was introduced as a damping which makes the solution independent of the starting model and its apparent fluctuation minimal the basic equations for delay times and smoothness are solved using the conjugate gradient method an iterative method which guarantees the convergence of solution into the exact least squares solution the weight on the smoothness i e the damping factor was objectively determined by a simplified cross validation technique the final solution was obtained as an average of the ten solutions each of which was derived from one tenth of the total data set the reliability of the solution is examined in two ways 1 mapping the resolution given by the reconstruction of checkerboard patterns and 2 mapping the variance given from the gaussian noise input this is the first result which delineates the whole mantle structure with its reliability mapping the longest wavelength anomalies of the lower mantle are similar to those of previous studies by dziewonski 1984 and hager and clayton 1989 however the shorter wavelength patterns have many discrepancies the fast anomalies of the uppermost mantle beneath the shield and the slow anomalies beneath the active tectonic regions are clearly seen we also revealed the l 2 pattern at the transition zone reported by the previous surface wave and free oscillation studies the most striking feature is that of the fast anomalies lying along the extension of the large subducting plate up to depths of about 1000 km or more the resolving powers in these regions are generally good

water table shapes and drain flow rates in shallow drainage systems abstract a relationship between drain flow rate elevation and shape of the water table and recharge intensity in shallow drainage systems is developed from an analytical spatial integration of the boussinesq equation in transient conditions drain flow rates are shown to be the sum of three terms the first one is proportional to the maximum water table elevation and more generally to the steady state flow rate at the same water table elevation the second one is a fraction of the recharge rate of the water table depending on the water table shape the third one accounts for possible changes in water storage in the water table due to its shape changes drain flow rates in shallow drainage systems are shown to be fully predicted by one unique variable that is a function of a combination of the hydraulic conductivity k the drainable porosity f and the drain spacing 2l namely k f2l2 this variable also determines the dynamics of changes in the water table shape and in turn the respective parts of the three terms in the equation it is shown that drainage systems with values of 1 m 1 h 1 respond very fast to recharge events water table shape changes occur very quickly so that the third component of the drain flow can be neglected in that case the equation results in a simplified analytical relationship the reliability of the complete and simplified equations to predict drain flow rates in transient conditions is discussed in relation to in situ measurements

migration of contaminants in groundwater at a landfill a case study 4 a natural gradient dispersion test abstract a natural gradient tracer test using a chloride solution with an initial injection volume of 0 7 m 3 was performed in the sandy aquifer at the borden site the solution was injected into five well points set 1 m below the water table in an uncontaminated zone situated above the contaminant plume at a location 450 m downflow from the landfill under conditions of natural groundwater flow the tracer slug was monitored for a period of 4 months by withdrawing small volume samples from points in a three dimensional array of bundle type multilevel samplers measurements of hydraulic head were obtained from a network of miniature piezometers soon after injection the tracer slug gradually split into two halves one half moving horizontally at an average velocity of 2 9 10 6 ms 1 and the other horizontally at 8 2 10 7 ms 1 although the split has been attributed to local lateral heterogeneity the nature of the heterogeneity and its influence on the hydraulic head distribution were not clearly distinguishable in the field data obtained before during or after the test the chloride patterns for each of the two halves of the tracer slug evolved into gaussian forms although the patterns demonstrated some irregularity at early time the relatively smooth gaussian forms were unexpected because the aquifer has numerous small scale heterogeneities observed in vertical cores obtained from the tracer zone and because the glaciofluvial origin of the aquifer suggests that heterogeneities are not laterally continuous simulated chloride distributions from a three dimensional analytical solution to the advection dispersion equation were fitted to the field data to obtain best fit estimates of the values of longitudinal transverse horizontal and transverse vertical dispersivity at various travel distances for each of the two halves of the tracer zone this is the first known field test that has permitted the estimation of three principal dispersion coefficients in layered media the longitudinal dispersivity was found to increase from 0 01 m at a distance of 0 75 m from the source to 0 08 m at 11 0 m the transverse horizontal dispersivity increased also to a value of 0 03 m at 11 0 m transverse vertical dispersion was very weak and was accounted for by molecular diffusion the relative lack of vertical dispersion is consistent with the shape of the plume of leachate contamination from the landfill it was concluded that the observed increase in dispersivity along the path of migration is likely caused by heterogeneities information on the dispersion controlling heterogeneities is not yet available as practical field methodologies for their identification and description have not yet been developed until such information is incorporated into mass transport models a realistic solution of the dispersion problem in heterogeneous media will remain elusive

numerical simulation of infiltration and solute transport in an s shaped model basin by a boundary fitted grid system abstract the boundary fitted grid method which transforms a complicated computational domain into a rectangular domain is applied for the moisture and solute transport problems in the unsaturated soil layer of an s shaped model hillslope in the transformed domain the fundamental equations of moisture and solute transport i e the richards equation and the fickian equation can be easily discretized into the finite difference form for three types of rainfall pattern a unit rainfall two unit successive rainfalls and two unit ranfalls with a lag between them hydrographs of total pre event and event water and event water discharges contour lines of soil moisture pressure and total hydraulic head distributions and flow velocity vectors are compared for a relatively thick soil layer or for a relatively light rainfall the capillary fringe effect plays an important role whereas for a relatively thin soil layer or for a relatively heavy rainfall overland flow from a variable source area is superimposed on the capillary fringe type runoff

isolating along strike variations in the depth extent of shallow creep and fault locking on the northern great sumatran fault the great sumatran fault system in indonesia is a major right lateral trench parallel system that can be divided into several segments most of which have ruptured within the last century this study focuses on the northern portion of the fault system which contains a 200 km long segment that has not experienced a major earthquake in at least 170 years in 2005 we established the aceh gps network for the sumatran fault system agness across this segment agness observes large displacements which include significant postseismic deformation from recent large megathrust earthquakes as well as interseismic deformation due to continued elastic loading of both the megathrust and the strike slip system we parameterize the displacements due to afterslip on the megathrust using a model based on a rate and state dependent friction formalism using this approach we are able to separate afterslip from other contributions we remove predicted deformation due to afterslip from the observations and use these corrected time series to infer the depth of shallow aseismic creep and deeper locked segments for the great sumatran fault in the northern portion of this fault segment we infer aseismic creep down to 7 3 4 8 km depth at a rate of 2 0 0 6 cm year in the southwestern portion of the segment we estimate a locking depth of 14 8 3 4 km with a downdip slip rate of 1 6 0 6 cm year this portion of the fault is capable of producing a magnitude 7 0 earthquake

geological framework of the laurentian trough aquifer system southern ontario the laurentian trough lt a depression 100 km long 3000 km2 in area and 100 m deep at the base of the niagara escarpment extends from within georgian bay to lake ontario it has a complex er

is the slip rate variation on the great sumatran fault accommodated by fore arc stretching in oblique convergent subduction areas an obliquity increase should produce a slip rate increase on trench parallel strike slip faults and thus the fore arc platelet should be stretched along the great sumatran fault gsf that is associated with the oblique convergent sunda arc a northward increase of the gsf slip rate occurs parallel with the convergence obliquity transpressional back arc deformation accommodates part of the gsf slip rate variation while no significant fore arc stretching is observed the sumatran case shows that oblique convergence may be accommodated by deformation of a 500 km wide zone from the fore arc to the back arc domains

deformation related to the 1994 liwa earthquake derived from geodetic measurements the deformation field around the southern great sumatran fault gsf in the vicinity of the february 15 1994 mw 6 8 liwa earthquake has been determined by geodetic survey geodetic trilateration and global positioning system gps measurements were carried out in july 1991 in the ranau lake liwa area a second geodetic survey reoccupied the same stations in september 1994 seven months after the liwa earthquake despite the limited number of benchmarks most of the measured displacement appears to be related to the 1994 earthquake in addition we show that most of this co seismic deformation is localized along a narrow zone corresponding to the gsf segment with a right lateral displacement of about 70 cm

hydrologic response of catchments to precipitation quantification of mechanical carriers and origins of water 1 precipitation induced overland and groundwater flow and mixing processes are quantified to analyze the temporal event and pre event water and spatial groundwater discharge and overland runoff origins of water entering a stream using a distributed parameter control volume finite element simulator that can simultaneously solve the fully coupled partial differential equations describing 2 d manning and 3 d darcian flow and advective dispersive transport mechanical flow driven by hydraulic potential and tracer based hydrograph separation driven by dispersive mixing as well as mechanical flow are simulated in response to precipitation events in two cross sections oriented parallel and perpendicular to a stream the results indicate that as precipitation becomes more intense the subsurface mechanical flow contributions tend to become less significant relative to the total pre event stream discharge hydrodynamic mixing can play an important role in enhancing pre event tracer signals in the stream this implies that temporally tagged chemical signals introduced into surface subsurface flow systems from precipitation may not be strong enough to detect the changes in the subsurface flow system it is concluded that diffusive dispersive mixing capillary fringe groundwater ridging and macropore flow can influence the temporal sources of water in the stream but any sole mechanism may not fully explain the strong pre event water discharge further investigations of the influence of heterogeneity residence time geomorphology and root zone processes are required to confirm the conclusions of this study

a noniterative technique for the direct implementation of well bore boundary conditions in three dimensional heterogeneous formations a noniterative algorithm for handling prescribed well bore boundary conditions while pumping or injecting fluid in a three dimensional heterogeneous aquifer is described the algorithm is formulated by superimposing conductive one dimensional line elements representing the well screen onto the three dimensional matrix elements epresenting the aquifer storage in the well casing is also naturally accommodated by the superposition of the line elements the numerical algorithm is verified by comparison with results obtained from the solution of papadopulos and cooper 1967 a large scale example problem involving groundwater extraction from a partially penetrating pumping well located in a highly heterogeneous confined aquifer is presented to demonstrate the utility of the approach

neotectonics of the sumatran fault indonesia the 1900 km long trench parallel sumatran fault accommodates a significant amount of the right lateral component of oblique convergence between the eurasian and indian australian plates from 10 n to 7 s our detailed map of the fault compiled from topographic maps and stereographic aerial photographs shows that unlike many other great strike slip faults the sumatran fault is highly segmented cross strike width of step overs between the 19 major subaerial segments is commonly many kilometers the influence of these step overs on historical seismic source dimensions suggests that the dimensions of future events will also be influenced by fault geometry geomorphic offsets along the fault range as high as 20 km and may represent the total offset across the fault if this is so other structures must have accommodated much of the dextral component of oblique convergence during the past few million years our analysis of stretching of the forearc region near the southern tip of sumatra constrains the combined dextral slip on the sumatran and mentawai faults to be no more than 100 km in the past few million years the shape and location of the sumatran fault and the active volcanic arc are highly correlated with the shape and character of the underlying subducting oceanic lithosphere nonetheless active volcanic centers of the sumatran volcanic arc have not influenced noticeably the geometry of the active sumatran fault on the basis of its geologic history and pattern of deformation we divide the sumatran plate margin into northern central and southern domains we support previous proposals that the geometry and character of the subducting investigator fracture zone are affecting the shape and evolution of the sumatran fault system within the central domain the southern domain is the most regular the sumatran fault there comprises six right stepping segments this pattern indicates that the overall trend of the fault deviates 4 clockwise from the slip vector between the two blocks it separates the regularity of this section and its association with the portion of the subduction zone that generated the giant m w 9 earthquake of 1833 suggest that a geometrically simple subducting slab results in both simple strike slip faulting and unusually large subduction earthquakes

a seepage face model for the interaction of shallow water tables with the ground surface application of the obstacle type method this paper presents a model to simulate overland flow genesis induced by shallow water table movements in hillslopes variably saturated subsurface flows are governed by the richards equation discretized by continuous finite elements on unstructured meshes an obstacle type formulation is used to determine where saturation conditions and thus seepage face conditions are met at the ground surface the impact of hillslope geometry boundary conditions and soil hydraulic parameters on model predictions is investigated on two dimensional test cases at the metric and hectometric scales the obstacle type formulation is also compared with a more detailed model coupling subsurface and overland flow the latter being described by the shallow water equations in the diffusive wave regime

surface wave tomography for southeastern asia using iris farm and jisnet data abstract previous seismic studies for southeastern asia around indonesia have used global seismic data and thus included few regional broadband seismic stations to better understand seismic structure of this area we temporarily deployed japan indonesia seismic network jisnet which was composed of 23 broadband seismic stations in central to western indonesia since 1998 under the super plume project of japan in this study we analyse regional jisnet data and global incorporated research institute of seismology iris fast archive recovery method farm data in order to obtain detailed images of 3d s wave velocity vs of this area we use vertical component lp seismograms of farm data recorded from 1989 to 1993 13471 seismograms and vertical component of broadband jisnet data recorded from 1998 to 2000 1782 seismograms we select seismic events with body wave magnitudes greater than 5 5 and take hypocenters and centroid moment tensor solutions from the harvard cmt catalogue phase velocity anomalies of fundamental mode rayleigh waves period from 34 to 197 s relative to preliminary reference earth model prem are determined by measuring phase differences between the synthetic waveforms and the observations global distribution of rayleigh wave phase velocities are determined by block inversions using damped least squares with a finer block size of 5 5 for the indonesia region than the surrounding area firstly we compare the results obtained from the inversion using the farm data alone called farm inversion and those from the inversion using both the farm and the jisnet data called jisnet farm inversion for the fundamental rayleigh waves of short periods phase velocities obtained from the jisnet farm inversion show greater degrees of negative anomaly throughout indonesia than those from the farm inversion the clearest difference is seen for the region around kalimantan and java slower phase velocities of less than 1 relative to prem at periods of about 70 s are obtained by the farm inversion whereas including jisnet data requires lower phase velocity anomalies of 2 5 secondly we compare the resolution kernels of both data set around java sumatra kalimantan and sulawesi the resolution of the jisnet farm inversion is substantially better than that of the farm data alone with the peaks of resolution kernels up to five times as high as those for the farm inversion the best resolution improvement is obtained for west kalimantan to java sea thirdly we invert the phase velocity perturbations for the modes to obtain the upper mantle 3d s wave velocity vs structure of the study area the jisnet farm inversion tends to give larger up to four times negative vs anomalies when compared with the farm inversion the vs heterogeneities concentrate in the uppermost mantle shallower than 200 km throughout indonesia beneath sumatra java and kalimantan the uppermost 100 km of the mantle is slower than prem by about 2 3 a prominent high vs anomaly 2 4 around the depths from 100 to 200 km extends from northern australia through the banda sea to east sulawesi and halmahera the subducted indian plate is visible as a nearly 1 high vs anomaly

the use of volcanic materials for the manufacture of pozzolanic plasters in the maya lowlands a preliminary report this paper focuses on the description and characterization of the nature of isotropic and silicon rich particles observed in plaster samples from the maya archaeological sites of calakmul and lamanai based on the composition and morphology of these particles it is proposed that volcanic ash and glass were incorporated into some of the ancient maya plasters in order to produce hydraulic reactions from a technological point of view the intent on the part of the maya to produce such reactions is relevant because it would reflect resource planning and complex knowledge of materials results also confirm previous reports of the presence of volcanic ash layers at the site of calakmul and suggest that there were considerable ash falls in the maya lowlands during prehispanic times which may have made the material available in many areas of the central lowlands if as we propose here volcanic ash was employed in lowland maya plasters then the use of volcanic materials by the lowland maya was more intensive than has been recognized our paper also reviews the literature about the use of volcanic materials in lowland maya materials and suggests future lines of research

nucleation of aragonite upon carbonation of calcium oxide and calcium hydroxide at ambient temperatures and pressures a new indicator of fire related human activities wood ash found at archaeological sites is the most direct evidence of the presence of combustion features the preservation of wood ash within archaeological deposits is often poor due to diagenetic processes and therefore its identification requires the use of spectroscopic methods ftir spectrometry is able to detect the main calcite component of wood ash unless this is mixed with other calcitic phases of geologic origin using ftir spectrometry we identified non biogenic aragonite in archaeological heat altered sediments and lime plasters the presence of aragonite in such conditions is unusual as it is unlikely to crystallize at ambient temperatures and pressures or in absence of mg the experimental conditions which favor the nucleation of this aragonite phase were investigated with ftir spectrometry xrpd and sem imaging of modern lime plaster and quicklime samples prepared in the laboratory using different calcium carbonate starting materials we show that aragonite forms at ambient temperatures and pressures upon carbonation of calcium oxide and calcium hydroxide together with calcite and its nucleation and growth are influenced by environmental parameters such as carbon dioxide partial pressure relative humidity and temperature this pyrogenic aragonite is a reliable indicator for calcareous materials exposed to temperatures above 600 c and therefore it can be used to determine the presence of heat altered sediments and ash in the absence of structured combustion features this mineral phase could have applications in radiocarbon dating as well

simulation of water flow on irrigation bay scale with mike she this study focuses on water flow of a 9 ha experimental irrigation site in a shallow water table area in the tragowel plains australia with the aim of quantifying the processes affecting surface drainage and groundwater levels the irrigation site was intensively monitored to provide the required input and calibration data for modelling the physical processes simulation of flow processes including infiltration capillary rise evapotranspiration overland flow groundwater exfiltration and groundwater flow into the drain was performed using the physically based distributed model mike she the model was calibrated against the observed piezometric levels drain flow and soil moisture data collected over a 19 month period that represented different field conditions under seasonal changes model simulations were generally consistent with the observed data however the results highlighted inadequacies of the model particularly in representing variations in rapid flow through macropores that occur due to the cracking and swelling properties of the soil despite this deficiency the modelling study allowed quantification of the effective flow processes and provided an insight into their implications in determining the quality i e salinity and quantity of drain flow and groundwater levels

effects of vadose zone on groundwater table fluctuations in unconfined aquifers summary above a shallow unconfined aquifer a considerable amount of water is stored in the vadose zone through water exchange with the underlying unconfined aquifer the vadose zone affects the groundwater table dynamics and overall behavior of the aquifer in this paper we examine tide induced groundwater table fluctuations in unconfined aquifers influenced by vadose zone of finite thickness under the condition of small aquifer thickness d compared with the groundwater wavelength l i e 2 d l 2 1 and small boundary oscillation amplitude a i e e a d 1 where 2 and e are two parameters an approximate analytical solution was derived to quantify systematically the vadose zone effects with a particular consideration of capping by the ground surface i e the upper boundary of the vadose zone depending on the extent to which the capillary rise is truncated by the ground surface the vadose zone enhances the groundwater table fluctuations in an unconfined aquifer however the mean groundwater table height and exchange between surface water and groundwater are reduced due to the presence of the vadose zone these effects are intensified with increased capillary rise but weakened as the vadose zone thickens this study provides a criterion for assessing the importance of vadose zone in modulating the response of unconfined aquifers to low frequency forcing oscillations such as tides

determination of magnitude for large shallow earthquakes 1898 1917 abstract in order to arrive at a uniform basis for a study of the global seismicity the surface wave magnitude ms of shallow earthquakes for 1898 1917 is newly determined by using maximum amplitudes of surface waves recorded by undamped milne and omori seismographs the effective gain of these instruments needs to be calibrated with great care because of the lack of a damping device the calibration of milne instruments is based on a comparison of amplitudes measured by milne instruments with those by more modern damped instruments the effective gain varies from 7 to 20 in the range of ms from 6 to 8 5 the reported amplitudes for the years 1910 1912 are twice as large as the standard and need to be corrected by applying these results to a wealth of the milne data ms is determined for a large number of earthquakes between 1898 and 1912 to supplement the data for 1913 1917 records of undamped omori seismographs are used for the entire period from 1898 to 1917 308 shallow earthquakes with m s 7 0 are listed here both this list and the previous catalogue of abe 1981 for 1918 1980 provide a catalogue of large shallow earthquakes much more uniform than any previously established between 1899 and 1910 the annual frequency of shocks with m s 7 0 is 20 which is twice as large as the annual average of 10 during 1911 and 1980

ecoulement sature et non sature de l eau souterraine vers des drains en aquifere a nappe libre the drainage of sports fields highways farm lands and covers for wastes corresponds to the drainage of a shallow unconfined aquifer resting on a horizontal or sloping impervious substratum the seepage partly saturated and partly unsaturated is thus described by nonlinear equations that are not easy to solve a few analytical solutions exist they were obtained after several simplifying assumptions are they realistic in this paper comparisons are made between predictions from analytical solutions and those from numerical resolutions for saturated and unsaturated seepage under steady and transient states the analytical solutions predict a water table and flow rates that differ significantly from those of the numerical resolutions and are sometimes unrealistic corrections to the analytical solutions have already been proposed to account for the vadose zone despite such corrections the published solutions to drainage problems may be inaccurate in engineering projects where the duration of dra

complements to magnitudes of large shallow earthquakes from 1904 to 1980 abstract in the previous paper magnitudes of large earthquakes of the world were determined on a very uniform basis and catalogued in order to arrive at a more homogeneous catalogue for a study of global seismicity some complements are presented the major complements are as follows 1 the m s values for the period 1904 1909 in the previous paper were overestimated in the extreme case by 0 5 magnitude units 2 the m b values for the period 1904 1908 in the previous paper were also overestimated 3 the magnitudes of deep and intermediate shocks which are listed in seismicity of the earth by gutenberg and richter are found to be approximated by m b m b 7 4 4 the catalogues of m b for shallow intermediate and deep shocks are continued for the period up to 1980

twin surface ruptures of the march 2007 m 6 earthquake doublet on the sumatran fault although the 2000 km long sumatran fault is one of earth s longest and historically most active strike slip faults previous large historical ruptures have gone unmapped although some have been inferred from felt reports or from modeling of sparse geodetic data through field observation we documented twin surface ruptures associated with two m 6 earthquakes in march 2007 the first rupture broke a 22 km part of the 60 km long sumani segment southeast from a releasing stepover the second rupture occurred on a 22 5 km part of the 90 km long sianok segment northwest from the stepover dextral displacements on the two segments averaged 51 and 36 cm the earlier earthquake doublet in 1926 also straddled this stepover but also did not seem to have ruptured the entire fault segments thus using fault lengths between large stepovers to estimate earthquake magnitude will overestimate what is likely to occur online material photos of surface rupture and surface displacement measurements

subducting oceanic crusts of the philippine sea and pacific plates and weak zone normal compression in the kanto district japan summary oceanic crusts subducting into the mantle were detected by analyses of mantle earthquakes in the kanto district central japan earthquakes in a depth range of 30 80 km in the southwestern ibaraki prefecture were relocated by a modified method of joint hypocentre determination we obtained a good distribution map of hypocentres and focal mechanisms a boundary layer between the eurasian and philippine sea plates was found where thrust earthquakes with p axes in the nw se direction and of which low angle nodal planes dip northward occurred in a layer with a thickness of about 4 km the p wave velocity in this layer is estimated to be less than about 7 0kms l another boundary layer between the philippine sea and pacific plates exists about 15 km beneath the above boundary layer thrust earthquakes with p axes in the ew direction and of which low angle nodal planes dip westward occurred in this layer that also has a thickness of about 4km furthermore normal faulting earthquakes of which the p axes are almost perpendicular to the boundary layers were found immediately outside the boundary layers combining these results we can conclude that the boundary layers are oceanic crusts that exist at the top of the subducting philippine sea and pacific plates weak zone normal compression was proposed to result from the existence of low velocity oceanic crusts at plate boundaries this hypothesis can be explained because only stress caused by relative motion of the two plates is consumed inside the weak oceanic crust the remnant stress after subtracting the above stress from the tectonic one applied at the plate boundary is the stress of which the p axis is normal to the plate boundary

quick aftershock relocation of the 1994 shikotan earthquake and its fault planes the 1994 shikotan earthquake of mw 8 2 occurred near the western kurile trench where the pacific plate is subducting beneath the north american plate although its mechanism is thrust type it is not a typical low angle thrust event with a nodal plane parallel to the plate boundary that occurs at the plate boundary in order to determine which of the two nodal planes of the main shock was the fault plane we relocated the main shock and all aftershocks with m 5 3 using a modified joint hypocenter determination method earthquakes on the northwestern side of the aftershock area including the main shock are located along a plane dipping east southeastward with a dip of 70 this plane is about 80 to 150 km long and 70 km wide the main shock occurred at the north northeastern bottom of this plane which is almost parallel to one of the two nodal planes of the main shock determined by harvard university which has a strike of n51 e and a dip of 76 thus we conclude that this plane is the fault plane that the fault broke at the northeastern bottom of the fault plane and that the rupture propagated to the surface and also to the southeast in addition to the aftershocks aligned with this fault plane there is a secondary alignment which is subparallel to the main fault plane and about 50 km east where the largest aftershock of mw 7 3 occurred on oct 9 since several aftershocks occurred on this secondary fault plane on the same day as the main shock it seems reasonable to suppose that this secondary fault plane was generated together with the main fault plane at the time of the main shock

migration of contaminants in groundwater at a landfill a case study 1 groundwater flow and plume delineation abstract a landfill derived contaminant plume with a maximum width of 600 m a length of 700 m and a maximum depth of 20 m in an unconfined sand aquifer was delineated by means of a monitoring network that includes standpipe piezometers multilevel point samplers and bundle piezometers the extent of detectable contamination caused by the landfill which began operation in 1940 and which became inactive in 1976 was determined from the distributions of chloride sulfate and electrical conductance in the sand aquifer all of which have levels in the leachate that are greatly above those in uncontaminated groundwater the maximum temperature of groundwater in the zone of contamination beneath the landfill is 12 c which is 4 5 c above background the thermal plume in the aquifer extends 150 m downgradient from the centre of the landfill a slight transient water table mound exists beneath the landfill in the late spring and summer in response to snowmelt and heavy rainfall beneath the landfill the zone of leachate contamination extends to the bottom of the aquifer apparently because of transient downward components of hydraulic gradient caused by the water table mound and possibly because of the higher density and lower viscosity of the contaminated water values of hydraulic conductivity which show variations due to local heterogeneity were obtained from slug tests of piezometers from pumping tests and from laboratory tests because of the inherent uncertainty in the aquifer parameter values the 38 yr frontal position of the plume calculated using the darcy equation with the assumption of plug flow can differ from the observed frontal position by many hundreds of metres although the use of mean parameter values produces a close agreement the width of the plume is large relative to the width of the landfill and can be accounted for primarily by variable periods of lateral east and westward flow caused by changes in water table configuration due to the variable nature of recharge northward from the landfill the vertical thickness of the plume decreases and the top of the plume is farther below the water table the thickness of the zone of uncontaminated groundwater above the plume increases northward as the area of recharge of uncontaminated water downflow from the landfill increases because dispersion in the vertical direction is weak there is very little mixing between the overlying zone of recharge water and the contaminant plume concentration profiles are irregular beneath and near the landfill and become smooth downgradient where the maximum concentrations are much less than those beneath landfill these features are attributed to a strong influence of longitudinal dispersion the plume passes beneath a small shallow stream near the landfill without significant influence on the stream

seismic history and seismotectonics of the sunda arc historic records of the last 300 years reveal two great interplate earthquakes 1833 mw 8 1861 mw 8 8 which ruptured major segments of the sumatra fore arc in western indonesia a significant percentage of interplate slip along this portion of the plate boundary appears to occur seismically the ends of these rupture zones are coincident with clusters of large ms 7 and moderate 6 ms 7 shocks and with heterogeneities in the plate interface as inferred from geologic and geophysical data the northern extent of the 1833 rupture zone is coincident with a group of moderate and large earthquakes a structural arch in the fore arc and a fracture zone on the subducted plate the southern portion is coincident with a very prominent cluster and the along strike extension of a sediment filled trough on the subducted plate prior to this study sumatra was characterized as relatively aseismic as inferred from the lack of great earthquakes in the instrumental record of this century java and the lesser sunda islands had major ms 6 earthquakes in the historic record but none are of the same magnitude as the great events near sumatra there is no clear evidence that shocks in the java fore arc were interplate events yet geophysical data indicate recent uplift of the trench slope break and a change in strike of the trench axis where the northernmost flank of the roo rise a prominent bathymetrie high appears to be interacting with the fore arc this feature was formed at a ridge crest and is more buoyant and thus more difficult to subduct than the surrounding seafloor there is no increase in seismicity associated with this tectonism however that may indicate a lack of contact between the crystalline portions of the plates at this time we infer that a majority of slip on the plate interface near java occurs aseismically the variation in occurrence of great interplate earthquakes along the sunda arc may be interpreted in terms of a model that attributes variation in interplate coupling to the age of the subducted lithosphere great interplate earthquakes occur near sumatra where the age of the youngest crust is 46 ma the characteristics of the sunda arc and analogies with pacific arcs imply that the entire length of sumatra has the potential to produce great thrust earthquakes its seismic potential should be considered high as there has been no recurrence of the great events of 1833 and 1861 in contrast no such events have been reported off java and the lesser sunda islands where the oldest crust is 152 ma the plate interface near java and the lesser sunda islands should be considered to have low seismic potential

two seismic gaps on the sagaing fault myanmar derived from relocation of historical earthquakes since 1918 1 relocation of six m magnitude 7 0 earthquakes near the sagaing fault in myanmar since 1918 allows us to image earthquake history along the sagaing fault all the earthquakes were relocated on the sagaing fault by using the modified joint hypocenter determination method combining the relocated epicenters with information on foreshocks aftershocks seismic intensities and coseismic displacement we estimated the location of the fault plane that ruptured during each earthquake this analysis revealed two seismic gaps one between 19 2 n and 21 5 n in central myanmar and another south of 16 6 n in the andaman sea considering the length of the first seismic gap 260 km a future earthquake of up to m 7 9 is expected to occur in central myanmar because nay pyi taw the recently established capital of myanmar is located on the expected fault its large population is exposed to a significant earthquake hazard

technology and decay of magnesian lime plasters the sculptures of the funerary crypt of palenque mexico abstract the full relief lime plaster sculptures of the funerary crypt of palenque mexico suffer from advanced decay due to the cave like environment in which they are located macroscopically the sculptures have a soft consistency but there is a hard crust over their surface some of the features observed by microscopy are the neomorphism of minerals as a consequence of permanent water seepage and the formation of wide shrinkage cracks as a result of drying the mineral hydromagnesite mg5 co3 4 oh 2 4h2o was identified by x ray diffraction and microscopy its relation with the shrinkage observed in the samples and its possible role in the decay of the sculptures are discussed in this paper a short discussion is also made about the likely raw materials that were employed to manufacture the sculptures

mantle structure beneath indonesia inferred from high resolution tomographic imaging we investigated mantle structure beneath the indonesian region by means of tomographic inversions of traveltime residuals of direct p and the surface reflected depth phases pp and pwp the hypocentres and phase data used in the inversions were derived from the reprocessing of data reported to international data centres which include data from the australian skippy project we used more than 6 0 10 data from more than 50 000 globally distributed earthquakes recorded at a subset of nearly 3000 seismological stations worldwide the use of depth phases improved the sampling of the upper mantle structure in particular beneath the back arc regions the mapping of distant aspherical mantle structure into the study region was minimized by combining a high resolution regional with a low resolution global inversion the inversion was linearized around the ak135 reference velocity model and a combination of minimum norm and gradient damping was applied to constrain the solution inversion of different subsets of the data and test inversions of synthetic data indicate that resolution is sufficient to substantiate the conclusions pertinent to the complex large scale structure of the subducted slab beneath the indonesian archipelago the tomographic images confirm previous evidence for regional slab penetration into the upper part of the lower mantle but suggest a more complex trajectory of mantle flow beneath indonesia the implied lateral variation in the shape of the upper mantle slab is generally in good agreement with inferences from seismicity the data reveal a seismic anomaly beneath the sunda arc which is detected to at least 1500 km in depth and forms the eastern end of a deep anomaly associated with the past subduction of lithosphere of the mesozoic tethys ocean below java the lithospheric slab is probably continuous from the earth s surface to the lower mantle but beneath sumatra the deep slab seems to be detached from the seismogenic slab the high resolution images suggest that the subducted slab is deflected in the transition zone beneath the banda arc and that the descending slabs form a spoon shaped structure north of the banda sea we detect the two opposing subducted slabs of the molucca sea plate this is consistent with previous studies but our images suggest that the westward subduction has a significantly steeper dip than the eastward subduction slab structure beneath the banda and molucca seas is explained in the context of the continent arc collision between australia and the southeast indonesian island arc and the arc arc collision between sangihe and halmahera inversion of traveltime residuals of direct s phases a novelty for this region largely confirms the inferences from the p wave data even though less detail is resolved

simulating groundwater flow and runoff for the oro moraine aquifer system part i model formulation and conceptual analysis a steady state groundwater model that incorporates the vadose zone in an approximate fashion is developed to account for situations where recharge may be significantly affected by heterogeneity above the water table the model is intended for basin scale applications where the exact representation of the unsaturated zone is no longer feasible the pseudo unsaturated model is compared to a variably saturated model making use of an idealized cross section approximating the complex oro moraine aquifer system differences in predicted flow regimes between the two models arise from the coarser mesh used in the pseudo unsaturated simulations but are minimal below the water table the pseudo unsaturated model yields an accurate overall system water mass balance although a loss in spatial resolution of predicted fluxes may occur such accuracy losses are offset by drastically lower computer memory requirements the flow simulations further show that near surface heterogeneity has a profound impact on the sustainable capacity of a groundwater system and the location of sensitive recharge areas the pseudo unsaturated model is then coupled to a high conductivity layer atop the model domain to simulate rainfall runoff an important advantage of this model formulation is that precipitation and evapotranspiration measurements can be directly used as model input while groundwater infiltration is part of the flow solution runoff and baseflow contributions to long term streamflow generation are also calculated and can be compared to data from gauging stations during model calibration

some experimental results concerning rapid water table response to surface phenomena abstract a review is made of transient phenomena relating to flow in the vadose zone reviewed topics include rapid water table response to rainfall pulsating flow due to pressure perturbations in the vadose zone and the wave like propagation of increased soil moisture caused by intermittent rainfall as a basis of interpreting these phenomena zoning of the vadose zone into a residual water zone an unsaturated capillary zone and a saturated capillary zone are proposed possible implications with respect to hydrological processes relating to these phenomena are discussed

field scale modeling of subsurface tile drained soils using an equivalent medium approach research conducted for the last 35 years has shown that subsurface drainage has a significant impact on hydrology and contaminant transport this can be observed at the field scale and also at the watershed scale impacts are always associated with modifying otherwise natural flow paths most computer model representations of drainage have been drawn at the field scale these models require relatively precise data that are usually unavailable when simulating hydrology and water quality in large watersheds we believe that in this case drainage representation should be simplified and yet closely match observations as a first step towards incorporating drainage systems into large scale hydrological models we propose an equivalent representation of drains buried in a soil profile by using a homogeneous anisotropic porous medium without drains this representation is based on a self consistent approach and on geometrical considerations simplification is such that calculating the equivalent hydraulic conductivity requires only information on the main length and spacing of the tile drains and not on their precise location this approach also provides a much simpler discretisation of the domain because of the absence of internal boundary conditions on the drainage pipes compared to other methods that have simplified drainage representation in existing watershed models it requires no parameter fitting two alternatives to the method are presented in the first one the soil profile equipped with the actual drain pipes is represented by an equivalent horizontally layered system with no pipes in the second the layered system has been replaced with an equivalent homogeneous profile the efficiency of these approaches was tested against a classical representation of tile drains using the swms 3d code which solves the richards equation for a typical drained plot configuration the equivalent medium approach appears to give satisfying results for global water outflow and mean water table elevation

calcareous fossil inclusions and rock source of maya lime plaster from the temple of the inscriptions palenque mexico abstract this paper introduces for the first time the study and description of fossil remains preserved in lime plaster from a maya site the temple of the inscriptions in palenque one of the most outstanding classic period cities of the maya culture in mesoamerica plaster was removed with edta carbonate digestive technique and results based on ultrastructural microanalysis reveals marine fossil remains of shells and calcareous debris correlated with organisms of several taxa including foraminifera gastropod bivalvia and cnidarian this fossil material is associated with several tertiary fossil bearing strata in the surroundings of palenque additionally results of wdx testing on white lumps of plaster show a characteristic mgo cao ratio consistent with a dolomitic limestone source linked to the tenejapa geological unit paleocene plaster of the temple of the inscriptions is best described as a dolomitic lime plaster calcareous fossil material in plaster mixtures is present mainly as micro aggregates and lime dust such material may come from a fossil bearing rock intentionally selected that was burned and crushed this also suggests that low temperatures can cause burns to incomplete calcination of rocks and consequently that fossils can preserve their recognizable morphological features

rupture along the great sumatran fault indonesia during the earthquakes of 1926 and 1943 while investigating features of quaternary displacement along the great sumatran fault zone in the padang highlands of sumatra indonesia figure 1 the authors incidentally came across heretofore unreported evidence of significant surficial displacements along the fault during the m s 6 earthquake of 28 june 1926 and the m s 7 6 earthquake of 9 june 1943 in both cases eyewitness reports by long term local residents allowed unequivocal documentation of the location and nature of the surficial fault displacements associated with the earthquakes although it was only through the use of vertical aerial photographs to locate the active fault trace that it was possible to concentrate the questioning in promising areas in every case it was thus possible to locate the primary active fault trace to within a few hundred meters before commencing the search for local eyewitnesses