a seismic landslide hazard analysis with topographic effect a case study in the 99 peaks region central taiwan it has been known that ground motion amplitude will be amplified at mountaintops however such topographic effects are not included in conventional landslide hazard models in this study a modified procedure that considers the topographic effects is proposed to analyze the seismic landslide hazard the topographic effect is estimated by back analysis first a 3d dynamic numerical model with irregular topography is constructed the theoretical topographic amplification factors are derived from the dynamic numerical model the ground motion record is regarded as the reference motion in the plane area by combining the topographic amplification factors with the reference motions the amplified acceleration time history and amplified seismic intensity parameters are obtained newmark s displacement model is chosen to perform the seismic landslide hazard analysis by combining the regression equation and the seismic parameter of peak ground acceleration and arias intensity the newmark s displacement distribution is generated subsequently the calculated newmark s displacement maps are transformed to the hazard maps the landslide hazard maps of the 99 peaks region central taiwan are evaluated the actual landslide inventory maps triggered by the 21 september 1999 chi chi earthquake are compared with the calculated hazard maps relative to the conventional procedure the results show that the proposed procedures which include the topographic effect can obtain a better result for seismic landslide hazard analysis

a three dimensional model of the m2 s2 n2 k1 and o1 tides in the celtic and irish seas abstract a three dimensional model using various parameterizations of eddy viscosity covering the celtic and irish sea region is used to examine the spatial distributions of the m2 s2 n2 k1 and o1 tidal elevations and phases computed cotidal charts and comparisons with observations from shore based and offshore gauges show good agreement comparisons are also made with a standard two dimensional model in shallow water regions the three dimensional model shows significantly less damping than the two dimensional model with an associated improvement in accuracy a detailed examination of differences between computed and observed tidal currents at over thirty locations having three or more current meters in the vertical show that the model can accurately reproduce the tidal current and its vertical profile in the eastern irish sea the region furthest from the model s open boundary good agreement with observations is obtained although in the deeper channel to the south of this the model over predicts current magnitude

mixing at camarinal sill in the strait of gibraltar during the gibraltar experiment in 1985 1986 observations of shear stratification microstructure and acoustic backscatter revealed a complex mixing regime at camarinal sill in the strait of gibraltar the mixing is forced by strong semidiurnal tidal currents and weaker but more steady baroclinic flows flows are characterized as outflow or inflow nearly equivalent to westward or eastward rising water at gibraltar coincides with outflow at all depths we observed two modes of outflow at the sill in may 1986 the transition layer separating atlantic and mediterranean water was between 0 75 mpa and 1 mpa when we sampled east of the sill near neap tide the transition turned down just before reaching the sill crest where the flow became critical increasing shear soon destabilized the transition producing billows which grew to 30 75 m on the west flank of the sill the overturning generated intense turbulence with peak dissipation rates e exceeding 10 2 w kg 1 this turbulence rapidly thickened the transition from z 30 50 m east of the sill to z 130 150 m within 1 2 km west of the sill from the rate of thickening we estimate the rate of formation of new transitional water during neap tide as 0 8 1 2 105 m3 s 1 this outflow mode did not release eastward propagating internal bores when outflow turned to inflow but the inflow did appear to arrest the deep outflow in may the largest average dissipation rate over and just west of the sill had the same magnitude as estimates of the net energy lost by adjustment of velocity and mass across the sill during outflow other averages are smaller than the energy loss presumably because the limited sampling severely underestimates the average dissipation rate during outflow strong shears were observed to rise to 100 times those in the background internal wave field however probably owing to spatial offsets between the ship s acoustic doppler current profiler and our tethered free fall profiler the only statistically significant correlations were found between overturning scales measured directly and those estimated from e in the same profile we observed the other outflow mode in october 1985 when we profiled over the sill near spring tide and the transition was east of the sill centered near 1 5 mpa after encountering the sill the transition rose sharply and remained within 10 20 m of the surface across the sill plunging steeply downward just past the west edge of the sill this was accompanied by intense turbulence and at least one rebound of the transition we did not observe release of eastward propagating bores when inflow turned to outflow but observations by armi and farmer 1988 in april 1986 found bores released at spring tide in regimes similar to the one we observed in october 1985

internal tides and turbulence along the 3000 m isobath of the hawaiian ridge full depth velocity and density profiles taken along the 3000 m isobath characterize the semidiurnal internal tide and bottom intensified turbulence along the hawaiian ridge observations reveal baroclinic energy fluxes of 21 5k w m 1 radiating from french frigate shoals 17 2 5 kw m 1 from kauai channel west of oahu and 13 3 5 kw m 1 from west of nihoa island weaker fluxes of 1 4 2k w m 1 radiate from the region near necker island and east of nihoa island observed off ridge energy fluxes generally agree to within a factor of 2 with those produced by a tidally forced numerical model average turbulent diapycnal diffusivity k is 0 5 1 10 4 m 2 s 1 above 2000 m increasing exponentially to 20 10 4 m 2 s 1 near the bottom microstructure values agree well with those inferred from a finescale internal wave based parameterization a linear relationship between the vertically integrated energy flux and vertically integrated turbulent dissipation rate implies that dissipative length scales for the radiating internal tide exceed 1000 km

landslides and other surface effects induced by the 1997 umbria marche seismic sequence abstract this paper both describes and discusses landslides and other ground effects induced by the september october 1997 seismic sequence which struck the umbria and marche regions central italy three main events occurred on 26 september at 00 33 and 09 40 gmt and 14 october with magnitude m w equal to 5 8 6 0 and 5 4 respectively furthermore hundreds of minor but significant events were also recorded the authors examined an area of some 700 km 2 around the epicentre colfiorito primary and secondary effects were observed including surface faulting phenomena landslides ground fractures compaction and various hydrological phenomena surface evidence of faulting reactivation was found along the well known capable faults to a total length of ca 30 km landslides which were the most recurrent among the phenomena induced consisted mainly of rock falls and subordinately of rotational and translational slides which were generally mobilised by the inertia forces during the seismic motion the percentage of reactivated old landslides decreased as the distance from the epicentral zone increased a similar decrease had been observed for the 1980 irpinia earthquake southern italy the ground fracture distribution was consistent with the regional structural setting and the general pattern of macroseismic field numerous episodes of hydrological changes were observed within the most severely damaged area all this evidence confirms the relevance of the study of ground surface effects for achieving a more complete evaluation of seismic hazard

landslides triggered by earthquakes and their relations with faults and mountain slope geometry an example from ecuador abstract a large number of landslides occurred during two seismic events respectively 6 9 and 6 1 msw on 5 march 1987 in the ecuadorian andes these landslides have been mapped digitized and coregistered with topography at 1 50 000 scale geometry of coseismic and holocene faulting has been assessed integrating field and geophysical data landslide distribution and holocene tectonic features have been compared with earthquake foci geological deposits slope area inclination and orientation and vegetation cover the macro seismic field deduced by landslide distribution is ellipse shaped with the major axis striking nne and coinciding with the trend of the coseismic and holocene faults landslide distribution also shows a correlation with respect to the dip direction of these faults and the orientation of mountain slopes slopes parallel to the coseismic fault planes sloping towards wnw are almost unaffected by landsliding while this increases on the slopes at high angle to the fault plane and lying along its strike if these results could be confirmed in other areas a method of reconstruction of geometry of seismogenetic faults from topographic effects appears feasible

spatial variability of turbulent mixing in the abyssal ocean ocean microstructure data show that turbulent mixing in the deep brazil basin of the south atlantic ocean is weak at all depths above smooth abyssal plains and the south american continental rise the diapycnal diffusivity there was estimated to be less than or approximately equal to 0 1 x 10 4 meters squared per second in contrast mixing rates are large throughout the water column above the rough mid atlantic ridge and the diffusivity deduced for the bottom most 150 meters exceeds 5 x 10 4 meters squared per second such patterns in vertical mixing imply that abyssal circulations have complex spatial structures that are linked to the underlying bathymetry

estimating open ocean barotropic tidal dissipation the hawaiian ridge the generalized inverse of a regional model is used to estimate barotropic tidal dissipation along the hawaiian ridge the model based on the linear shallow water equations incorporates parameterizations for the dissipation of energy via friction in the bottom boundary layer and form drag due to internal waves generated at topographic slopes sea surface height data from 364 orbit cycles of the ocean topography experiment topex poseidon satellite mission are used to perform inversions at eight diurnal and semidiurnal tidal frequencies it is estimated that the barotropic m2 tide loses energy at a rate of 19 gw of which 88 is lost within 250 km of the ridge presumably via conversion to the internal or baroclinic tide uncertainty in the assumed model error and wave drag in the forward model suggest that m2 dissipation values from 18 to 25 gw are consistent with the altimetric observations other barotropic tidal constituents are estimated to lose a total of 5 7 gw the spatial distribution of barotropic dissipation along the ridge is similar to that inferred from three dimensional primitive equation models and it is largely insensitive to details of assumed model and data errors dissipation at semidiurnal frequencies is most intense at the french frigate shoals with lesser but significant contributions at other sites diurnal tidal dissipation is concentrated to the east of the french frigate shoals at the gardner pinnacles further work with threedimensional models will be necessary to determine the fate of the energy that is removed from the barotropic tide

tidally forced internal waves and overturns observed on a slope results from home abstract tidal mixing over a slope was explored using moored time series observations on kaena ridge extending northwest from oahu hawaii during the survey component of the hawaii ocean mixing experiment home a mooring was instrumented to sample the velocity and density field of the lower 500 m of the water column to look for indirect evidence of tidally induced mixing and was deployed on a slope in 1453 m water depth for 2 months beginning in november 2000 the semidiurnal barotropic tidal currents at this site have a significant cross ridge component favorable for exciting an internal tidal response a large amplitude response is expected given that the slope of the topography 4 5 is nearly the same as the slope of the internal wave group velocity at semidiurnal frequency density overturns were inferred from temperature profiles measured every 2 min the number and strength of the overturns are greater in the 200 m nearest the bottom with overturns exceeding 24 m present at any depth nearly

analysis of the seismic origin of landslides examples from the new madrid seismic zone by analyzing two landslides in the new madrid seismic zone we develop an approach for judging if a landslide or group of landslides of unknown origin was more likely to have formed as a result of earthquake shaking or in aseismic conditions the two landslides analyzed are representative of two groups of land slides that previous research on the geomorphology and regional distribution of landslides in this region indicates may have been triggered by the 1811 1812 new madrid earthquakes slope stability models of aseismic conditions show that neither landslide is likely to have formed aseismically even in unrealistically high ground water conditions dynamic stability analysis using newmark s method shows that both slides probably would have experienced large inertial displacements during earthquake shaking similar to that which occurred in 1811 1812 these displacements are large enough that catastrophic failure is highly probable thus the stability analyses are consistent with other lines of evidence that these landslides formed as a result of strong earthquake shaking during the 1811 1812 earthquakes our analysis yields a general relationship between newmark landslide displacement earthquake shaking intensity and the critical acceleration of a landslide using this relationship we estimate the minimum shaking intensities required to trigger the types of landslides studied an mb 5 8 or m 5 9 earthquake is the lower bound threshold at zero epicentral distance that could trigger catastrophic movement of typical block slides in the new madrid seismic zone for earth flows mb 5 4 or m 5 3 is the threshold earthquake

intense variable mixing near the head of monterey submarine canyon abstract a microstructure survey near the head of monterey submarine canyon the first in a canyon confirmed earlier inferences that coastal submarine canyons are sites of intense mixing the data collected during two weeks in august 1997 showed turbulent kinetic energy dissipation and diapycnal diffusivity up to 103 times higher than in the open ocean dissipation and diapycnal diffusivity within 10 km of the canyon head were among the highest observed anywhere e 1 1 10 6 w kg 1 k 1 0 10 2 m2 s 1 mixing occurred mainly in an on axis stratified turbulent layer with thickness and intensity increasing from neap to spring tide strain spectra showed a gentler than k 1z rolloff suggesting that critical reflection and scattering may push energy into high wavenumbers dissipation dependence on shear appears to be much weaker in the canyon than in the open ocean with indications that the dependence maybe as low as e s coastal canyons may account for a small but significant fraction of the int

the geotechnical effects of long human habitation 2000 years earthquake induced landslide hazard in the city of zefat northern israel abstract this work studies the effects of long human habitation on site geotechnical conditions it is focused on the city of zefat that is located on the borders of the dead sea transform in northern israel the city of zefat suffered severe damage and loss of life in historical earthquakes as a consequence of earthquake induced landslides eils in this work we evaluate the current eils hazard for the city of zefat using a gis based regional newmark analysis with calibration of the calculated newmark displacement representing eils hazard using maps of field evidence and historical documents testifying to slope instability that occurred in historical earthquakes we found that the core city of zefat is built on a layered anthropogenic material few meters deep which was deposited as a result of more than 2000 years of human habitation the anthropogenic material is mechanically weak susceptible to slope failure and to amplification of seismic shaking it is responsible for the city s devastation in historical earthquakes and it is the source for the current high seismic hazard as well our model shows that earthquakes of magnitudes mw 5 6 and 7 at distances of up to 10 km 50 km and more than 100 km respectively are likely to induce landslides in the core city of zefat the current engineering status of the city is poor and as a consequence severe damage and loss of life are expected in future earthquakes due to eils unless major engineering efforts are made cities in the eastern mediterranean with comparable long habitation histories e g jerusalem tiberias nablus amman are expected to have similar geotechnical problems in their old sections and are advised to take appropriate engineering steps to reduce damage and loss of life in future earthquakes evaluation of historical earthquake magnitudes based on reported local damage may however lead to overestimated magnitudes where the damaged sites are built on anthropogenic talus a common setting in the vicinity of the dead sea transform

from tides to mixing along the hawaiian ridge the cascade from tides to turbulence has been hypothesized to serve as a major energy pathway for ocean mixing we investigated this cascade along the hawaiian ridge using observations and numerical models a divergence of internal tidal energy flux observed at the ridge agrees with the predictions of internal tide models large internal tidal waves with peak to peak amplitudes of up to 300 meters occur on the ridge internal wave energy is enhanced and turbulent dissipation in the region near the ridge is 10 times larger than open ocean values given these major elements in the tides to turbulence cascade an energy budget approaches closure

slope stabilization and landslide size on mt 99 peaks after chichi earthquake in taiwan the study focuses on the landslide characteristics of mt 99 peaks in nantou county the most serious landslide prone area caused by chichi earthquake in taiwan several investigations and field surveys were made on mt 99 peaks for 5 years to research the landslide area and depth rainfall trend and slope stabilization the total landslide volume caused by the earthquake on mt 99 peaks was about 1 47 106 m3 and the mean landslide thickness was about 0 22 m gravel layers with a volume of more than 80 of total soil profile dominated mt 99 peaks the landslide on mt 99 peaks was induced by heavy rainfall from july to september because the rainfall on mt 99 peaks had a nonuniform distribution in time although the vegetation recovery on mt 99 peaks was in progress the soil slope had remained unstable as a result typhoon mindulle occurred in july 2004 collapsed the hillslope again after 5 years of chichi earthquake this study suggests that vegetation recovery on mt 99 peaks for 5 years was insufficient to stabilize the landslide affected area

the application of predictive modeling techniques to landslides induced by earthquakes the case study of the 26 september 1997 umbria marche earthquake italy abstract during september and october 1997 an earthquake sequence of moderate magnitude struck the umbria and marche regions central italy as a consequence of the most severe shocks several landslides were triggered on bedrock calcareous debris and sandy clay deposits the landslide inventory collected in the field and by aerial photo interpretation provided an opportunity to test the accuracy of existing predictive relations for landslide hazard zoning and to formulate new ones shallow soil slides and debris slides were selected to verify the prediction performance of the methods which are based on a simplified model geotechnique 15 1965 139 that calculate landslide displacements during cyclic seismic loading rock falls were modeled using a different approach to produce an empirical predictive rule for determining the probability of detachment of blocks when landslides occur along pre existing or newly formed failure surfaces the arias intensity and destructiveness potential are the strong ground motion parameters that best relate to displacements the predictive relation proposed for rock falls evaluates the probability of occurrence as a function of the slope angle and the peak ground acceleration pga

terrain attributes of earthquake and rainstorm induced landslides in orogenic mountain belt taiwan landsliding induced by earthquakes and rainstorms in montane regions is not only a sculptor for shaping the landscape but also a driver for delivering sediments and above ground biomass downstream however the terrain attributes of earthquake and rainstorm induced landslides are less discussed comprehensively in taiwan as part of an island wide inventory we here compare and contrast the landslide terrain attributes resulting from two catastrophic events the chi chi earthquake mw 7 6 september 1999 and typhoon morakot rainfall 2500 mm august 2009 results show that the earthquake induced landslides are relatively small round shaped and prone to occur primarily in middle and toe of slopes in contrast the rainstorm induced landslides are larger horseshoe shaped and preferentially occurring in slope toes also earthquake induced landslides particularly large landslides are usually found at steeper gradients whereas rainstorm induced landslides aggregate at gradients between 25 and 40 lithologic control plays a secondary role in landsliding from an island wide perspective high landslide density locates in the region of earthquake intensity vi or one day rainfall 600 mm day 1 through the landslide patterns and their terrain attributes our retrospective approach shed lights on accessing the historical and remote events for close geophysical investigations finally we should bear in mind that the landslide location size and terrain attributes varying with triggers may affect the landscape evaluation or biogeochemical processes in landslide dominated regions this article is protected by copyright all rights reserved

determining landslide susceptibility in central taiwan from rainfall and six site factors using the analytical hierarchy process method this work provides a landslide susceptibility assessment model for rainfall induced landslides in central taiwan based on the analytical hierarchy process method the model considers rainfall and six site factors including slope geology vegetation soil moisture road development and historical landslides the rainfall factor consists of 10 day antecedent rainfall and total rainfall during a rainfall event landslide susceptibility values are calculated for both before and after the beginning of a rainfall event the 175 landslide cases with detailed field surveys are used to determine a landslide susceptibility threshold value of 9 0 when a landslide susceptibility assessment value exceeds the threshold value slope failure is likely to occur three zones with different landslide susceptibility levels below slightly above and far above the threshold are identified the 9149 landslides caused by typhoon toraji in central taiwan are utilized to validate the study s result approximately 0 2 0 4 and 15 3 of the typhoon caused landslides are located in the three landslide susceptibility zones respectively three villages with 6 6 0 4 and 4 9 of the landslides respectively are used to validate the accuracy of the landslide susceptibility map and analyze the main causes of landslides the landslide susceptibility assessment model can be used to evaluate susceptibility relative to accumulated rainfall and is useful as an early warning and landslide monitoring tool

model estimates of m2 internal tide energetics at the hawaiian ridge 1 a primitive equation model is used to examine the structure and energetics of m 2 internal tides generated at the hawaiian ridge recent estimates based on altimeter data suggest that 20 gw of barotropic tidal dissipation occurs at the ridge with conversion to internal tides believed to be the dominant dissipation mechanism the model simulates an internal tide that accounts for 9 7 gw of radiated energy away from the ridge in the northeast and southwest directions the strongest generation occurs at three sites where enhanced barotropic currents flow across elongated topographic features the depth integrated baroclinic energy flux and energy densities at these sites are on the order of 10 4 w m 1 and 10 4 j m 2 respectively a modal decomposition indicates that 62 of the outgoing energy flux is accounted for by the first internal mode 15 is accounted for by the second mode and less than 5 is accounted for by each subsequent higher mode the tidal dissipation due to bottom friction along the ridge is estimated to be 0 1 gw the level of turbulent dissipation near the ridge owing to tidal energy conversion remains to be determined to assess fully the barotropic baroclinic energy budget

the relationship between slope gradient and lateritic cobble orientation with respect to shape northwestern taiwan in situ investigations of lateritic cobble slopes have demonstrated that where the grain orientation is more uniform the anisotropy is more obvious grain orientation will also affect the slope gradient and slope surface the slope forms an escarpment when the intersection between the cobble orientation strike and the slope surface ranges between 90 and 180 by contrast there is a dip slope geometry when the angle of intersection is 0 the slope gradient increases and has an angle of 50 to 80 when the intersected angle ranges from 0 to 180 the results indicate a positive relationship between these two factors the slope grade will increase when the disk and bladed grain shape of the cobbles increase their percentage relative to the material composition on the other hand the slope gradient decreases when the proportion of equant and roller grain shapes of cobble increase in the composition

flow and mixing around a small seamount on kaena ridge hawaii abstract microstructure observations over a small seamount on the kaena ridge hawaii showed asymmetry in the along and across ridge directions the 400 m high seamount is on the southern edge of the ridge centered at 21 43 49 n 158 38 48 w 42 km northwest of oahu a 1 km resolution numerical simulation shows that the flow within the depth range of the seamount tends to be accelerated around the seamount rather than going up and over it the flow patterns however are more complicated than for an isolated seamount because of the influence of the 3000 m high kaena ridge comparison with the numerical simulations indicates that the across ridge asymmetry in which dissipation on the north northeastern side of the seamount was higher and more concentrated toward the bed than on the south southwestern side is consistent with an m2 tidal beam generated at the northern edge of the ridge the along ridge asymmetry with higher dissipation on the east southeastern flank than on the west northwestern fla

buoyancy forcing by turbulence above rough topography in the abyssal brazil basin abstract observations of turbulent dissipation above rough bathymetry in the abyssal brazil basin are presented relative to regions with smooth bathymetry dissipation is markedly enhanced above rough topography of the mid atlantic ridge with levels above bathymetric slopes exceeding levels observed over crests and canyon floors furthermore mixing levels in rough areas are modulated by the spring neap tidal cycle internal waves generated by barotropic tidal flow over topography are the likely mechanism for supplying the energy needed to support the observed turbulent dissipation a model of the spatial and temporal patterns in the turbulent dissipation rate is used to constrain the diapycnal advection in an inverse calculation for the circulation in an area of rough bathymetry this inverse model uses both beta spiral and integrated forms of the advective budgets for heat mass and vorticity and contains sufficient information to resolve the full three dimensional flow the inverse model solution re

the effect of orientation and shape distribution of gravel on slope angles in central taiwan abstract we compare gravel orientation and slope angle distribution to highlight their possible relationship with various gravel shapes in the ninety nine peaks area in central taiwan in the study area four gravel shapes disk equant bladed and roller are collected and studied disk and equant shapes comprise more than 65 of the gravel eighty five percent weight of gravel particles is composed of quartz sandstone sand particles only make up 14 of the matrix the matrix strength ranges from 100 to 250 kg cm2 the slope angle ranges from 60 to 70 and more than 50 of the study area consists of such slopes linear regression analysis shows that when the proportion of disk bladed and roller shapes in the gravel increases the slope angle increases although the linear relationship remains indistinct an important inverse relationship is that as the proportion of equant shapes in the gravel increases the slope angle clearly performs differently by decreasing the results of the investigation also show that the slope angle is lower when the imbrication direction of the gravel is parallel to the slope surface

shaking intensity thresholds for rock falls and slides evidence from 1987 whittier narrows and superstition hills earthquake strong motion records due to inconsistencies in using descriptive intensity scales to describe earthquake shaking necessary to trigger landslides arias intensity a quantity calculated from seismic strong motion records has been employed as a measure of the seismic energy required to initiate landslides because arias intensity is defined as the sum of all the squared acceleration values from a strong motion record it is a measure of the energy dissipated at a site by shaking it incorporates both amplitude and duration information making it more useful to compare with the failure of slopes than parameters such as peak acceleration arias intensities calculated from the 24 october 1987 superstition hills and the 1 october 1987 whittier narrows earthquakes in southern california allow comparisons with the limits of landslides specifically falls and slides from rock and soil in these two earthquakes these comparisons establish two shaking thresholds for the limits of falls and slides a range of 0 08 to 0 6 m sec is observed for tertiary and younger deposits while the range of 0 01 to 0 07 m sec is observed for mesozoic and older rocks these two ranges of shaking levels are controlled by the relative degree of fracturing and aperture of fracture systems within the two general age groups of rocks and soils in the los angeles area and the imperial valley

observations of boundary mixing over the continental slope observations of mixing over the continental slope using a towed body reveal a great lateral extent several kilometers of continuously turbulent fluid within a few hundred meters of the boundary at depth 1600 m the largest turbulent dissipation rates were observed ove ra5k mhorizontal region near a slope critical to the m2 internal tide over a submarine landslide perpendicular to the continental slope enhanced mixing extended at least 600 m above the boundary increasing toward the bottom the resulting vertical divergence of the heat flux near the bottom implies that fluid there must be replenished intermediate nepheloid layers detected optically contained fluid with u s properties distinct from their surroundings it is suggested that intermediate nepheloid layers are interior signitures of the boundary layer detachment required by the near bottom flux divergance

significant dissipation of tidal energy in the deep ocean inferred from satellite altimeter data how and where the ocean tides dissipate their energy are long standing questions1 that have consequences ranging from the history of the moon2 to the mixing of the oceans3 historically the principal sink of tidal energy has been thought to be bottom friction in shallow seas4 5 there has long been suggestive evidence6 7 however that tidal dissipation also occurs in the open ocean through the scattering by ocean bottom topography of surface tides into internal waves but estimates of the magnitude of this possible sink have varied widely3 8 9 10 11 here we use satellite altimeter data from topex poseidon to map empirically the tidal energy dissipation we show that approximately 1012 watts that is 1 tw representing 25 30 of the total dissipation occurs in the deep ocean generally near areas of rough topography of the estimated 2 tw of mixing energy required to maintain the large scale thermohaline circulation of the ocean12 one half could therefore be provided by the tides with the other half coming from action13 on the surface of the ocean

idealized solutions for the energy balance of the finescale internal wave field abstract recent fine and microstructure observations indicate enhanced finescale shear and strain in conjunction with bottom intensified turbulent dissipation above rough bathymetry in the brazil basin such observations implicate the bottom boundary as an energy source for the finescale internal wave field simple analytical and numerical solutions to an equation governing the spatial and temporal evolution of the finescale wave field are described here the governing equation implicitly treats the effects of wave breaking on the vertical propagation of internal waves through a flux representation of nonlinear transports associated with internal wave wave interactions these solutions identify the rate of dissipation of turbulent kinetic energy with downscale energy transports at high vertical wavenumber resulting in an estimate of dissipation versus depth the sensitivity of the turbulent dissipation depth profile to various environmental parameters is examined observed dissipation profiles and shear

dynamic analysis of a slope failure from the 6 august 1979 coyote lake california earthquake abstract the coyote lake california earthquake of 6 august 1979 m l 5 7 provided a rare opportunity to perform a dynamic numerical analysis of a seismically induced slope failure using actual strong motion records the earthquake displaced a preexisting slump on the northeast shore of lake anderson and formed a fissure 20 m long offsets of 9 mm vertically and 18 mm horizontally were measured across the fissure the slump is 9 km northwest of the located epicenter but within 100 m of the mapped trace of the calaveras fault two strong motion records were written in the vicinity of the slump coyote creek 5 km to the southeast and gilroy 6 15 km to the southeast these records combined with field measurements of the slope estimates of the material properties and a dynamic numerical model based on the newmark analysis of seismic slope stability to calculate a predicted displacement for the landslide a displacement of 27 mm calculated using the n50 e component of the gilroy 6 record is in excellent agreement with the displacement measured in the field 21 mm however displacements of only 0 12 mm calculated using the 250 component of the coyote creek strong motion record reflect significant local variations in seismic shaking intensity because strong motion records and slope failures rarely coincide this landslide provides an important test case for our understanding of the dynamics of seismically induced landslides as well as a warning that local seismologic variations need to be considered in any design applications

characteristics of rainfall induced landslides in miocene formations a case study of the shenmu watershed central taiwan abstract fractured and high permeability miocene formations exhibiting shallow soil layers and dense faults and an increasing number of heavy rainfall events have caused severe and frequent landslides in the shenmu watershed of central taiwan the shenmu watershed exhibited a landslide ratio that was typically greater than 1 0 during heavy rainfall events between 1996 and 2009 and can be considered one of the most landslide prone areas in taiwan the landslide ratio in the lower hillslopes is approximately 2 8 to 43 3 times greater compared with that in the upper hillslopes analyzing based on a self organized criticality soc perspective indicated that the value of the shenmu watershed 1 24 1 26 was the lowest among landslide prone areas implying that small landslides dominated the distribution of landslides documented in available records the six large landslides that occurred include four shallow landsides and two deep seated landslides with a landslide depth greater than 10 m approximately 82 3 of the small landslides constituted bank erosion landslides in the downstream watershed whereas 96 2 of the large landslides occurred in upstream areas with dense faults large landslides occurred during only heavy rainfall events in which the accumulated rainfall was greater than 1000 mm in fractured and high permeability strata with dense faults the large landslides deposited considerable amounts of sediment into streams inducing significant bank erosion landslides in the downstream watershed bank erosion in the downstream watershed caused additional small landslides along the river large landslides were typically caused by a fault density of 693 6 m km2 fractured strata with a permeability of 10 3 to 10 4 m s and high levels of accumulated rainfall exceeding 1000 mm the apparent increase in bank erosion which increased from 103 to 136 between 1996 and 2009 resulted from an increasing number of heavy rainfall events and the amount of sediment deposition caused by major landslides frequent landslides result from the increasing number of heavy rainfall events fractured rock exhibiting dense faults and steep and shallow soil morphology in the shenmu watershed

an estimate of tidal energy lost to turbulence at the hawaiian ridge abstract an integrated analysis of turbulence observations from four unique instrument platforms obtained over the hawaiian ridge leads to an assessment of the vertical cross ridge and along ridge structure of turbulence dissipation rate and diffusivity the diffusivity near the seafloor was on average 15 times that in the midwater column at 1000 m depth the diffusivity atop the ridge was 30 times that 10 km off the ridge decreasing to background oceanic values by 60 km a weak factor of 2 spring neap variation in dissipation was observed the observations also suggest a kinematic relationship between the energy in the semidiurnal internal tide e and the depth integrated dissipation d such that d e1 0 5 at sites along the ridge this kinematic relationship is supported by combining a simple knife edge model to estimate internal tide generation with wave wave interaction time scales to estimate dissipation the along ridge kinematic relationship and the observed vertical and cross ridge st

regionalization of rainfall thresholds an aid to landslide hazard evaluation rainfall soil properties and morphology are major factors controlling shallow landsliding a series of meteorological events that triggered soil slips in northern italy were studied to define rainfall thresholds and to evaluate a possible regionalization soil properties triggering rainfall and local lithological and morphometrical settings of different sites were used as input to an infiltration model the approach allows the recognition of several triggering conditions in the piedmont pre alpine and alpine regions this suggests the need for different rainfall thresholds with respect to those derived with other methods intensity versus rainfall duration relationships become particularly important when related to soil permeability and thickness and demonstrate the role of antecedent precipitation events with exceptional water discharge from obstructed road culverts reveal the role played by anthropic structures in triggering such phenomena different approaches to slope stability analysis are shown taking into account bedrock lithology topography seepage and local saturation conditions

internal tide radiation from mendocino escarpment abstract strong semidiurnal internal tides are observed near mendocino escarpment in full depth profile time series of velocity temperature and salinity velocity and density profiles are combined to estimate the internal tide energy flux divergence of this flux demonstrates that its source is the barotropic tide interacting with the escarpment a baroclinic energy flux of 7 kw m 1 radiates from the escarpment corresponding to 3 of the 220 kw m 1 fluxing poleward in the surface tide energy and energy flux are concentrated in packets that emanate from the flanks of the ridge surmounting the escarpment and one site 90 km north of the escarpment coherent beamlike structure along semidiurnal ray paths remains identifiable until the first surface reflection beyond the first surface reflection north of the escarpment the energy flux drops by 2 kw m 1 and beams are no longer discernible turbulence as inferred from finescale parameterizations is elevated by over two orders of magnitude relative to th