intraseasonal interactions between the tropics and extratropics in the southern hemisphere abstract the mechanics of the interaction between tropical beating estimated from outgoing longwave radiation olr and southern hemisphere sh subtropical and extratropical circulations on intraseasonal time scales are discussed base points are selected from teleconnectivity and teleconnection maps between olr and zonal wind heights and meridional component of the divergent wind then composites are formed for pentads with olr anomalies at the base point greater in magnitude than one standard deviation enhanced convection over indonesia is found to be associated with increases of both the southward component of the meridional divergent wind and of the westerly zonal wind to the south of the heating region during the sh summer the increased westerly wind gradients resulting to a certain extent from strengthened northerly flow together with increased values of the southward component of the divergent wind lead to an enhancement of the rossby wave source in the vorticity equation in the vicinit

a threshold based earthquake early warning system for offshore events in southern iberia the south of the iberian peninsula is situated at the convergence of the eurasian and african plates this region experiences large earthquakes with long separation in time the best known of which was the great 1755 lisbon earthquake which occurred sw of san vicente cape sw iberian peninsula the high risk of damaging earthquakes has recently led carranzaet al geophys res lett 40 2013 to investigate the feasibility of an eews in this region analysis of the geometry for the iberian seismic networks and the san vicente cape area led the authors to conclude that a threshold based approach which would not require real time location of the earthquake might be the best option for an eews in sw iberia in this work we investigate this hypothesis and propose a new eew approach that extends standard p wave threshold based single station analysis to the whole network the proposed method enables real time estimation of the potential damage at stations that are triggered by p waves and those which are not triggered with the advantage of greater lead times for release of alerts results of tests made with synthetic data mimicking the scenario of the great 1755 lisbon earthquake and those conducted by applying the new approach to available recordings indicate that an eew estimation of the potential damage associated with an event in the san vicente cape area can be obtained for a very large part of the iberian peninsula

influence of the madden julian oscillation on precipitation and surface air temperature in south america the regional influence of the madden julian oscillation mjo on south america is described maps of probability of weekly averaged rainfall exceeding the upper tercile were computed for all seasons and related statistically with the phase of the mjo as characterized by the wheeler hendon real time multivariate mjo rmm index and with the olr mjo index the accompanying surface air temperature and circulation anomalies were also calculated the influence of the mjo on regional scales along with their marked seasonal variations was documented during december february when the south american monsoon system is active chances of enhanced rainfall are observed in southeastern south america sesa region mainly during rmm phases 3 and 4 accompanied by cold anomalies in the extratropics while enhanced rainfall in the south atlantic convergence zone sacz region is observed in phases 8 and 1 the sesa sacz signal is characterized by upper level convergence divergence over tropical south america and a cyclonic anticyclonic anomaly near the southern tip of the continent impacts during march may are similar but attenuated in the extratropics conversely in june november reduced rainfall and cold anomalies are observed near the coast of the sacz region during phases 4 and 5 favored by upper level convergence over tropical south america and an anticyclonic anomaly over southern south america in september november enhanced rainfall and upper level divergence are observed in the sacz region during phases 7 and 8 these signals are generated primarily through the propagation of rossby wave energy generated in the region of anomalous heating associated with the mjo

patterns and processes of shell fragmentation in modern and ancient marine environments shell fragments are important components of many recent and fossil marine benthic ecosystems and can provide crucial information on past and present environmental conditions interpreting such fragments requires integrated knowledge in various fields and the information potential is therefore rarely optimally utilized this paper uses the definition of a fragment as being a piece of shell having less than 90 of its original form it then outlines the potential characteristics pathways and fates that shells and their fragments can have fragmentation is a key factor shaping the shelly part of death assemblages but it is difficult to interpret because it can be broadly caused by ecological biostratinomic or diagenetic processes and also depends on shell strength strength in turn reflects multifunctionality during ontogeny and depends on a complex set of skeletal and taphonomic factors therefore no particular shell parameter clearly determines strength but thickness microstructure type and degree of organic matrix have the strongest influence on pre and post mortality strength size measurements are usually less important for shell strength than thickness although ecologically complex size refuges from predation do exist similarly shell shape sculptural features and specific aperture types in gastropods provide various defence strategies rather than increasing strength per se key ecological factors of fragmentation include predation due to crushing peeling along with mistaken predation selfinflicted damage during predation and burrowing and more physical aspects such as impacts by stones modern studies must consider damage by benthic commercial fisheries or dredging by scientific vessels key biostratinomic factors include transportinduced abrasion littoral zone of surf washed beaches bioerosion and dissolution mainly sublittoral environments diagenetically fragmentation during compaction mainly occurs when shells are in direct contact with one another or with coarser grains taphonomic features e g drillholes have only minor influence a key step in interpreting fragments is to categorize breakage into repaired versus unrepaired diagnostic versus nondiagnostic and severe versus localized damage quantifying the above categories can then provide useful information on breakage patterns and underlying processes understanding the many characteristics of shells and their fragments is a significant interpretive tool in maximizing the information gain in palaeoecological and taphofacies analyses d 2003 elsevier science b v all rights reserved

intraseasonal oscillations in the global atmosphere part ii southern hemisphere abstract in part ii of this two part article we complete the systematic examination of oscillatory modes in the global atmosphere by studying 12 years of 500 mb geopotential heights in the southern hemisphere as in part i for the tropics and northern hemisphere extratropics the data were band pass filtered to focus on intraseasonal is phenomena and spatial eofs were obtained the leading principal components were subjected to singular spectrum analysis ssa in order to identify nonlinear is oscillations with high statistical confidence in the southern hemisphere the dominant mode has a period of 23 days with spatial patterns carried by the second and third winter eof of the is band it has a zonal wavenumber four structure the 40 day mode is second and dominated by wavenumbers three and four while a 16 day mode is too weak to separate its spatial behavior from the previous two the is dynamics in the southern hemisphere is more complex and dominated by shorter wavenumbers than the northern

magnitude estimation using the covered areas of strong ground motion in earthquake early warning 1 we collected the strong motion accelerograms with peak ground acceleration pga larger than 100 gal 1 gal 1 0 cm s 2 from large crustal earthquakes in taiwan recorded by the taiwan strong motion instrumentation program tsmip stations to find an empirical relationship between the area of high pga and the corresponding earthquake magnitude we found that the logarithms of the areas inside the pga contours have a linear relation to the corresponding earthquake magnitudes we propose that this relationship might be able to rapidly define the earthquake magnitude while providing sufficient seismic station coverage and might have practical application in earthquake early warning eew and rapid reporting systems the proposed magnitude estimation method is directly related to the level of strong surface shaking and is inherently suitable for the purpose of the eew and rapid reporting systems

the potential for earthquake early warning in italy using elarms abstract the new italian national seismic network insn is a dense network of broadband stations deployed for monitoring italian seismicity the network consists of 250 stations with a typical station spacing of 40 km earthquake early warning is the rapid detection of an event in progress assessment of the hazard it poses and transmission of a warning ahead of any significant ground motion we explore the potential for using the insn real time network for the purpose of earthquake early warning we run the elarms early warning methodology off line using a data set of more than 200 events with magnitudes between 2 5 and 6 0 a scaling relation for magnitude determination from the dominant period of the first seconds of signal following the p onset is developed from the data set the standard deviation in the magnitude estimates using this approach is 0 4 magnitude units and all event magnitude estimates are within 0 75 magnitude units of the true magnitude given the existing distribution of seismic stations it takes an average of 10 sec after event initiation before the p wave has been detected at four stations if we require a detection at four stations before issuing the first alert then the blind zone within which no warning would be available has a radius of 37 km the elarms methodology can provide a warning earlier than this but with a greater uncertainty an assessment of past damaging earthquakes across italy shows that applying elarms with the existing seismic network could provide warning to population centers in repeats of past events for example in a repeat of the 1980 irpinia earthquake naples could receive an 15 sec warning the variations in the size of the blind zone and warning times for different regions can be used as a guide to selecting strategic locations for future station deployments

storm tracks in the southern hemisphere abstract from 1979 to 1989 global european centre for medium range weather forecasts ecmwf analyses of many meteorological variables important in baroclinic storms have been bandpass filtered to highlight fluctuations on 2 to 8 day time scales in order to illuminate the relationships among the variables in baroclinic storm track regions because of the greater zonal symmetry in the southern hemisphere sh versus the northern hemisphere nh it is possible to examine these relationships over a zonal sector without being dominated by local effects associated with jet stream entrance and exit regions of the storm tracks the bandpassed variance of geopotential height is used to define the storm track and its meridional profile has a pronounced midlatitude maximum in the sh the locations of the jet stream and the variance maxima of meridional and zonal velocity components vorticity vertical motion specific humidity and temperature all bear a distinctive relationship to the storm track but the lat

magnitude determination using strong ground motion attenuation in earthquake early warning 1 we use 1661 strong motion accelerograms with peak ground acceleration pga larger than 80 gal 1 gal 1 0 cm s2 from 77 earthquakes recorded by the taiwan strong motion instrumentation program tsmip stations to derive a strong motion attenuation relationship this relationship can be used to dynamically define a mpga magnitude for earthquakes using earthquake locations determined by earthquake early warning process the mpga magnitude using this strong motion attenuation relationship corresponds well with mw given a sufficient number of pga readings mems micro electro mechanical systems acceleration sensor could be widely used for ground motion monitoring purposes thus we propose that once a large earthquake has begun that we might be able to use strong near field tens of kilometers pga values to quickly estimate the earthquake s magnitude which would improve earthquake early warning

a new method of quickly estimating epicentral distance and magnitude from a single seismic record rapid estimation of the epicentral distance and magnitude is of fundamental importance for early earthquake detection and warning systems we present a novel method of estimating the epicentral distance from a single seismic record in a short amount of time in order to quantitatively evaluate the difference in observed seismic waveforms we introduced a simple function with the form of bt exp at and determined a and b in terms of the least squares method by fitting this function to the initial part of the waveform envelope we have found that log b is inversely proportional to log where is the epicentral distance this relation holds true regardless of the earthquake magnitude by using this relation we can roughly estimate the epicentral distance nearly immediately after the p wave arrival then we can readily estimate the magnitude from the maximum amplitude observed within a given short time interval after the p wave arrival by using an empirical magnitude amplitude relation that includes the epicentral distance as a parameter manuscript received 11 january 2002

influence of the intraseasonal variability on heat waves in subtropical south america the influence of the intraseasonal variability on heat wave development over subtropical south america during austral summer is analyzed the role of the south atlantic convergence zone sacz on this development is documented results show that intraseasonal variability can explain on average at least 32 of summer temperature variance moreover 73 of the heat waves in subtropical south america develop in association with an active sacz the analysis of pentad maps shows that warm conditions in the region under study develop in association with the strengthening of an anticyclonic anomaly which is discernible over the subtropical regions at least 15 days before temperature peak occurrence that circulation anomaly is embedded in a large scale rossby wave train extending along the south pacific ocean that is linked to convection anomalies at the equatorial western and central pacific ocean in addition the development of the anticyclonic circulation over subtropical south america appears to be strengthened by the subsidence conditions promoted by the active sacz which result in temperature rise in the subtropical region under relatively dry conditions on the other hand during the last 2 days of evolution sacz activity weakens and the progressive temperature rise in the region is dominated by warmer and moister air being anomalously advected from the north results confirm the important role that sacz activity on intraseasonal time scales has in inducing persistent circulation anomalies at the subtropical regions that can result in the development of persistent heat waves and very extreme daily temperature

an automatic processing system for broadcasting earthquake alarms in japan most of the damage caused by large earthquakes is concentrated within areas less than about 100 km from the focal regions we have developed an earthquake alarm system that determines earthquake parameters within a few seconds of the p wave s arrival at the closest station and then transmits the earthquake information before the s wave arrival in areas of possible serious earthquake damage since an earthquake alarm system requires the determination of reliable earthquake parameters as quickly as possible it is unreasonable to wait until waveform data from numerous stations have been collected for analysis for this reason we have developed a novel method of determining the hypocentral location by using the arrival times for only a few stations as well as the lack of p wave arrivals at other stations at a given time the use of not yet arrived data makes it possible not only to determine reliable hypocenter parameters within a few seconds but also to detect erroneous arrival time readings and remove them automatically since the available waveform data increases with time the system was designed to redetermine earthquake parameters every second our method was deployed in a real time system starting in july 2002 the real time system locates 10 20 events per day which includes a few felt earthquakes occurring in and around japan it was shown from the waveform data for about 100 felt earthquakes that almost all the events except those far from the network could be located within a few seconds when most of seismic energy has not even arrived at some stations close by we recently started widespread broadcasting of earthquake information in real time by using a satellite transmission system

real time moment magnitude and stress drop with implications for real time shaking prediction abstract despite the potentially dramatic effect of the stress drop on ground motion intensity currently available earthquake early warning systems that deliver peak ground motion predictions do not account for the effect of this parameter to address this issue a new evolutionary algorithm for determining stress drop and moment magnitude in real time is described it consists of two distinct modules one processes data recorded by individual stations and another computes event average stress drops and moment magnitudes to speed up the analysis the real time algorithm deviates from standard procedures of stress drop determination in several ways because these time saving measures come at the price of accuracy a quality control parameter is introduced which quantifies the discrepancy between the observed and modeled ground motion the results of implementing the algorithm offline using kik borehole data from japan are presented it is shown that it is possible to recover the moment magnitudes and the stress drops in real time two example timelines of seismic moment and stress drop are presented these show that the source parameters of small to moderate earthquakes may be estimated quite accurately within 5 to 10 s since the first trigger whereas those of larger magnitudes i e m w 6 take 20 30 s finally ground motion prediction equations for the velocity s root mean square and peak ground velocity are presented once the epicenter seismic moment and stress drop are determined using a few stations nearest to the epicenter their values can be input into those equations to get the ground motion intensity at sites further away from it

examination of scaling between proposed early signals in p waveforms and earthquake magnitudes summary we examine seismic waveforms generated by clusters of similar earthquakes and additional events located on the karadere duzce branch of the north anatolian fault to investigate possible scaling between proposed early signals in the p waveforms and magnitudes the employed signals can be divided into two classes the first is associated with ellsworth beroza and iio type signals that are assumed to reflect signatures of seismic nucleation phases the second are associated with nakamura type period and wu zhao type maximum displacement in the early waveforms that are related to measures of the corner frequency and local magnitude respectively the impact on each signal of artefacts generated by the finite impulse response fir filter is also examined the use of repeating event clusters reduces considerably the variability of path and site effects compared to previous regional and global studies this allows us to focus more accurately on variations of the potential scaling parameters with the source magnitude however the magnitude range of the employed events is limited to about 4 units the fir filter artefacts can generate spurious signals prior to the p wave arrival potentially affecting the ellsworth beroza type signals but are not a significant influence on any of the other measurements the results indicate that candidates for the ellsworth beroza signals associated with identification of a weak arrival before the main p phase exist in less than 20 per cent of the cases the iio type signals can be determined by definition on all waveforms both of these potential signatures of nucleation phases show little or no scaling with the final event size in the examined data in contrast the nakamura and wu zhao type signals in the first few seconds which can also be determined by definition on all waveforms appear to scale with the final event magnitude albeit with large scatter the relatively large time windows used in the analysis compared to the rupture time of the employed events implies that the results provide little if any information on the physical process of the rupture initiation the scaling of the nakamura and wu zhao type early signals with the final event size may be explained by statistical tendency of stronger initial rupture phases to propagate larger distances

blocking in the southern hemisphere abstract the focus of this paper is on the frequency and spatial distributions of blocking and persistent anomalies of geopotential height over the southern hemisphere the analysis is based upon daily height fields at 1000 and 500 mb for both summer and winter histogram frequency distributions of height anomalies and maps of the skewness and kurtosis have been computed blocking events are objectively defined by requiring a large positive anomaly to exist for 5 days or more composite flow and anomaly fields for several cases are presented and examined in detail the geographical distribution of the frequency of lame amplitude 150 gpm anomalies at 500 mb that persist for only 1 3 days is very similar to that of the high frequency band 2 8 day period variances that identity the storm tracks in the southern hemisphere the primary location for blocking in the southern hemisphere is in the new zealand sector and blocking occurs through a local enhancement of the climatological split in the mean westerli

an empirical evolutionary magnitude estimation for early warning of earthquakes abstract the earthquake early warning eew system is difficult to provide consistent magnitude estimate in the early stage of an earthquake occurrence because only few stations are triggered and few seismic signals are recorded one of the feasible methods to measure the size of earthquakes is to extract amplitude parameters using the initial portion of the recorded waveforms after p wave arrival however for a large magnitude earthquake m w 7 0 the time to complete the whole ruptures resulted from the corresponding fault may be very long the magnitude estimations may not be correctly predicted by the initial portion of the seismograms to estimate the magnitude of a large earthquake in real time the amplitude parameters should be updated with ongoing waveforms instead of adopting amplitude contents in a predefined fixed length time window since it may underestimate magnitude for large magnitude events in this paper we propose a fast robust and less saturated approach to estimate earthquake magnitudes the eew system will initially give a lower bound of the magnitude in a time window with a few seconds and then update magnitude with less saturation by extending the time window here we compared two kinds of time windows for measuring amplitudes one is p wave time window ptw after p wave arrival the other is whole wave time window after p wave arrival wtw which may include both p and s wave one to ten second time windows for both ptw and wtw are considered to measure the peak ground displacement from the vertical component of the waveforms linear regression analysis are run at each time step 1 to 10 s time interval to find the empirical relationships among peak ground displacement hypocentral distances and magnitudes using the earthquake records from 1993 to 2012 in taiwan with magnitude greater than 5 5 and focal depth less than 30 km the result shows that considering wtw to estimate magnitudes has smaller standard deviation than ptw the magnitude estimations using 1 s time widow have larger uncertainties progressively adopting peak displacement amplitudes p d from 2 to 10 s wtw is suggested for eew systems

intraseasonal variability of wintertime frontal activity and its relationship with precipitation anomalies in the vicinity of south america the intraseasonal variability of the frontal activity and its connection with the variability of the atmospheric circulation and precipitation in the southern hemisphere is studied the frontal activity is defined as the relative vorticity times the local temperature gradient a band pass filter was applied to retain the intraseasonal timescales an empirical orthogonal function analysis was applied to the filtered frontal activity anomalies the two main modes show positive and negative centers located mainly over the southern pacific ocean and south american sector and are in quadrature with each other a similar pattern was found when the main modes of intraseasonal variability of the 500 hpa geopotential height were projected on the frontal activity suggesting that the variability of fronts are influenced by the variability of the large scale atmospheric circulation moreover the precipitation anomalies projected on the main modes of both frontal activity and 500 hpa geopotential height show similar structures especially over the southern pacific ocean and south america which may indicate that the variability of fronts controls the variability of precipitation the lagged regression of the time series of the frontal activity areally averaged over one of the centers of action against the frontal activity anomaly field shows at lags 8 and 8 a similar pattern suggesting a period of around 17 days for each mode moreover lagged regression between times series of frontal activity and precipitation anomalies reveals an opposite pattern between southeastern south america and southern chile being precipitation anomalies over these two regions anti correlated due to the frontal activity

teleconnection patterns and rossby wave propagation associated to generalized frosts over southern south america based on previous observational studies of the mean atmospheric circulation leading to generalized frosts gf in central southern south america it is possible to establish a hypothesis that specific large scale patterns are associated to the frequency of occurrence of these events through the propagation of rossby waves remotely excited this hypothesis is tested here through a teleconnection analysis for austral winters which present an extreme frequency of occurrence of gf in southeastern south america particularly over the wet pampa area in argentina rossby wave propagation regions are identified for two basic states given by the composition of winters with maximum and minimum frequency of gf occurrence during the 1961 1990 period the stationary wavenumber k s indicates the regions where the rossby wave propagation is permitted and those where it will be inhibited k s 0 highlighting the importance of the jets as waveguides nevertheless differences exist between both basic states analyzed these differences indicate that the locations for wave generation and its later evolution are conditioned by the basic state results are validated through a baroclinic model which simulates the rossby wave patterns responsible for the teleconnection numerical experiments confirm that the principal wave activity takes place inside the subtropical and polar jets in particular for the basic state with maximum frequency of gf occurrence the wave trains propagating inside the subtropical and polar waveguides merge just before entering the continent as shown by the observations prior to the occurrence of gf events this configuration favors the development of an intense south wind anomaly with large meridional extension which results in the intensification of anticyclonic circulation in southern south america a conceptual model is presented to summarise all these results

subseasonal variations of rainfall in south america in the vicinity of the low level jet east of the andes and comparison to those in the south atlantic convergence zone abstract regional and large scale circulation anomalies associated with variations in rainfall downstream of the south american low level jet are identified and compared to those in the south atlantic convergence zone sacz composites of precipitation associated with strong jets reveal an approximate doubling of the quantities one would expect from climatology with an evolution of the rainfall pattern from south to north the occurrence of extreme precipitation events follows a similar pattern meridional cross sections of composite wind reveal a distinct low level jet near 20 s and a baroclinic development farther south that appears to force the jet geopotential height temperature and large scale wind composites suggest that this developing disturbance is tied to a wave train that originates in the midlatitude pacific and turns equatorward as it crosses the andes mountains similar composites based on sacz rainfall reveal similar features but of opposite sign suggesting that the phase of the wave

earthquake early warning for southern iberia a p wave threshold based approach 1 the south of the iberian peninsula is a region in which large damaging earthquakes occur separated by long time intervals an example was the great 1755 lisbon earthquake intensity imax x which occurred sw of san vicente cape sw iberian peninsula due to this risk of damaging earthquakes the implementation of earthquake early warning system eews technologies is of considerable interest with the aim of investigating the feasibility of an eews in this region of the iberian peninsula empirical scaling relationships have been derived between the early warning parameters and the earthquake size and or its potential damaging effects for this region an appropriate and suitable strategy is proposed for an eews in the sw iberian peninsula which takes into account the limitations of the existing seismological networks

revised ml determination for crustal earthquakes in taiwan the local magnitude scale m l is an empirically derived scale anchored to a zero magnitude reference event richter defined the amplitude of ground shaking at an epicentral distance of 100 km for a zero magnitude earthquake in southern california the crustal attenuation characteristics of taiwan result in a relatively high ml when compared to moment magnitude mw we therefore define a revised ml scale for crustal earthquakes in the taiwan region that is more consistent with mw using observed peak ground shaking and mw we determine a new log a0 curve of ground shaking versus hypocentral distance r for a zero magnitude earthquake and station correction factors the log a0 curve determined in this study is log a r 0 332 1 568 log r 0 280 0 using this new log a0 curve and station corrections the new ml is more consistent with mw with a 0 2 magnitude unit uncertainty the new log a0 curve has a value of 2 80 at the distance of 100 km compared to the anchor point of log a0 3 at the same distance as defined by richter for southern california this means that the current ml estimates in taiwan which use richter s definition average 0 2 magnitude units larger than their mw the station correction factors also determined are large from 0 40 to 0 52 magnitude units the use of station corrections in routine seismic network operation in taiwan will improve magnitude estimates this is particularly important for smaller events when recording stations may be pre dominantly on either hard rock or soft soil sites which could lead to under or overestimates of the magnitude by up to half a magnitude unit

estimating earthquake magnitude with early arrivals a test using dynamic and kinematic models recent studies on seismological data indicate that earthquake magnitude scales with either the dominant period or the peak amplitude in the seismogram s first few seconds at first sight this may indicate that the earthquake s final size is some how related to the way rupture starts one working hypothesis is that strong radiation from the initial phase of rupture is indicative of a triggering asperity releasing a con sistent amount of elastic energy with the potential to drive the fracture to large extents we tested this concept with a number of numerical simulations but within the models investigated scaling was found only for ruptures extending up to about four times the size of the initial asperity at larger distances the correlation was lost alternatively a careful kinematic analysis of the earthquake source radiation shows that the initial signal recorded at any station does not necessarily correspond to the rupture initiation but may represent an extended portion of the radiating source using the concept of isochrones we show that the apparent scaling may be explained by a simple kinematic model respecting causality up to a given magnitude threshold where the scaling re lation saturates the saturation level is in agreement with that observed in some but not all of the real seismicity catalogs online material additional synthetic kinematic catalogs

magnitude determination using initial p waves a single station approach 1 prompted by recent success in the research and application of earthquake early warning systems we conducted an investigation into the relationship between the magnitudes of earthquakes and the properties of the first three seconds of the p waves at a single station using waveforms at station nacb of the broadband array in taiwan for seismology from 46 earthquakes within 100 km epicentral distance we found a linear correlation between the magnitudes and the logarithmic characteristic periods of the initial p waves for earthquakes up to magnitude 6 5 we also detected a deterministic relationship between the magnitudes and the peak amplitudes of the initial p waves for earthquakes of magnitude m 6 5 while further study needs to be done on the behavior of the initial p wave peak amplitudes from larger earthquakes we propose here that the characteristic periods and peak amplitudes of the first three seconds of the p waves be used jointly in onsite single station earthquake early warning operations

characteristics of the southern hemisphere winter storm track with filtered and unfiltered data abstract the structure and evolution of the fluctuations in synoptic scales in the southern hemisphere sh during winter are discussed using six years of european centre for medium range weather forecasts analyses it is shown that patterns from unfiltered meridional wind series in the sh display all the features needed to represent the synoptic scale waves typical periods and wavelengths are similar to those observed in the northern hemisphere 4 days 4000 km although over the pacific ocean they can be as high as 7 8 days and 4700 km respectively as in the northern hemisphere tilts are not geographically fixed but change with the stage of the evolution of the wave the phase speed of the waves agrees with the low level winds in extensive areas of the middle latitudes and ranges from 12 m s 1 in the indian ocean to 6 m s 1 in the pacific ocean the estimated group velocities achieve maximum values of about 38 m s 1 also in the indian ocean and agree with the upper level maximum winds in accor

circulation regimes and low frequency oscillations in the south pacific sector abstract the characteristics of subseasonal circulation variability over the south pacific are examined using 10 day lowpass filtered 700 hpa geopotential height ncep ncar reanalysis data the extent to which the variability in each season is characterized by recurrent geographically fixed circulation regimes and or oscillatory behavior is determined two methods of analysis a k means cluster analysis and a cross validated gaussian mixture model both indicate three to four geographically fixed circulation regimes in austral fall winter and to some extent spring the spatial regime structures are found to be quite similar in each season they resemble the so called pacific south american psa patterns discussed in previous studies and often referred to as psa 1 and psa 2 oscillatory behavior is investigated using singular spectrum analysis this identifies a predominantly stationary wave with a period of about 40 days and a spatial structure similar to psa 1 it is most pronounced in winter and spr

subpolar high anomaly preconditioning precipitation over south america abstract the mechanisms associated with the intraseasonal variability of precipitation over south america during the spring season are investigated with emphasis on the influence of a quasi stationary anomalous circulation over the southeastern south pacific ocean sep a spectral analysis performed to the bandpass filtered time series of daily precipitation anomalies for the la plata basin lpb and the south atlantic convergence zone sacz regions revealed several statistically relevant peaks corresponding to periods of roughly 23 days and 14 16 days with the lower higher frequency peaks more prevalent for the sacz lpb the large scale circulation patterns preconditioning precipitation variability over both regions were explored by means of a regression analysis performed on the daily 500 hpa geopotential anomaly field provided by the ncep ncar reanalysis dataset the most prominent feature of the regression fields is the presence of a quasi stationary anomalous anticyclonic cyclonic circulation

real time magnitude characterization of large earthquakes using the predominant period derived from 1 hz gps data earthquake early warning eew systems performance is driven by the trade off between the need for a rapid alert and the accuracy of each solution a challenge for many eew systems has been the magnitude saturation for large events mw 7 and the resulting underestimation of seismic moment magnitude in this study we test the performance of high rate 1hz gps based on seven seismic events to evaluate whether long period ground motions can be measured well enough to infer reliably earthquake predominant periods we show that high rate gps data allow the computation of a gps based predominant period g to estimate lower bounds for the magnitude of earthquakes and distinguish between large mw 7 and great mw 8 events and thus extend the capability of eew systems for larger events it is also identified the impact of the different value of the smoothing factor on the g results and how the sampling rate and the computation process differentiates g from the commonly used p

determination of earthquake early warning parameters τ c and pd for southern california summary we explore a practical approach to earthquake early warning in southern california by determining a ground motion period parameter c and a high pass filtered displacement amplitude parameter pd from the initial 3 s of the p waveforms recorded at the southern california seismic network stations for earthquakes with m 4 0 at a given site we estimate the magnitude of an event from c and the peak ground motion velocity pgv from pd the incoming threecomponent signals are recursively converted to ground acceleration velocity and displacement the displacements are recursively filtered with a one way butterworth high pass filter with a cut off frequency of 0 075 hz and a p wave trigger is constantly monitored when a trigger occurs c and pd are computed we found the relationship between c and magnitude m for southern california and between pd and pgv for both southern california and taiwan these two relationships can be used to detect the occurrence of a major earthquake and provide onsite warning in the area around the station where onset of strong ground motion is expected within seconds after the arrival of the p wave when the station density is high the methods can be applied to multistation data to increase the robustness of onsite early warning and to add the regional warning approach in an ideal situation such warnings would be available within 10 s of the origin time of a large earthquake whose subsequent ground motion may last for tens of seconds

fast determination of earthquake magnitude and fault extent from real time p wave recordings s u m m a r y this work is aimed at the automatic and fast characterization of the extended earthquake source through the progressive measurement of the p wave displacement amplitude along the recorded seismograms we propose a straightforward methodology to quickly characterize the earthquake magnitude and the expected length of the rupture and to provide an approximate estimate of the average stress drop to be used for earthquake earlywarning and rapid response purposes we test the methodology over a wide distance and magnitude range using a massive japan earthquake accelerogram data set our estimates of moment magnitude source duration length and stress drop are consistent with the ones obtained by using other techniques and analysing the whole seismic waveform in particular the retrieved source parameters follow a self similar constant stress drop scaling median value of stress drop 0 71 mpa for the m 9 0 2011 tohoku oki event both magnitude and length are underestimated due to limited available p wave time window ptws and to the low frequency cut off of analysed data we show that in a simulated real time mode about 1 2 seconds would be required for the source parameter determination of m 4 5 events 3 10 seconds for m 6 7 and 30 40 s for m 8 8 5 the proposed method can also provide a rapid evaluation of the average slip on the fault plane which can be used as an additional discriminant for tsunami potential associated to large magnitude earthquakes occurring offshore

magnitude estimation using the first three seconds p wave amplitude in earthquake early warning 1 pd is the peak amplitude of displacement in the first three seconds after the arrival of the p wave we investigated the attenuation of pd with the hypocentral distance r in southern california as a function of magnitude m and obtained the following relationship log pd 3 463 0 729 m 1 374 log r 0 305 given an earthquake location determined by the p wave arrival times at stations close to the epicenter this relationship can be used to define a so called pd magnitude of earthquakes our result shows that for earthquakes in southern california the pd magnitudes agree with the catalog magnitudes with a standard deviation of 0 18 for events less than magnitude 6 5 therefore pd is a robust measurement for estimating the magnitudes of earthquakes and has practical application in earthquake early warning systems citation wu y m and l zhao 2006 magnitude estimation using the first three seconds p wave amplitude in earthquake early warning geophys res lett 33 l16312 doi 10 1029 2006gl026871

a threshold based earthquake early warning using dense accelerometer networks most earthquake early warning systems eews developed so far are conceived as either regional network based or on site stand alone systems the recent implementation of nationwide high dynamic range dense accelerometer arrays makes now available potentially in real time unsaturated waveforms of moderate to large magnitude earthquakes recorded at very short epicentral distances 10 20 km this would allow for a drastic increase of the early warning lead time for example the time between the alert notification and the arrival time of potentially destructive waves at a given target site by analysing strong motion data from modern accelerograph networks in japan taiwan and italy we propose an integrated regional on site early warning method which can be used in the very first seconds after a moderate to large earthquake to map the most probable damaged zones the method is based on the real time measurement of the period c and peak displacement pd parameters at stations located at increasing distances from the earthquake epicentre the recorded values of early warning parameters are compared to threshold values which are set for a minimum magnitude 6 and instrumental intensity vii according to the empirical regression analyses of strong motion data at each recording site the alert level is assigned based on a decisional table with four alert levels defined upon critical values of the parameters pd and c which are set according to the error bounds estimated on the derived prediction equations given a real time evolutionary estimation of earthquake location from first p arrivals the method furnishes an estimation of the extent of potential damage zone as inferred from continuously updated averages of the period parameter and from mapping of the alert levels determined at the near source accelerometer stations the off line application of the method to strong motion records of the m w 6 3 2009 central italy earthquake shows a very consistent match between the rapidly predicted within a few seconds from the first recorded p wave and observed damage zone the latter being mapped from detailed macroseismic surveys a few days after the event the proposed approach is suitable for italy where during the last two decades a dense network of wide dynamic range accelerometer arrays has been deployed by the department of civil protection dpc the istituto nazionale di geofisica e vulcanologia ingv and other regional research agencies

quick and reliable determination of magnitude for seismic early warning this article reports efforts toward using real time earthquake monitoring by the taiwan central weather bureau to meet the needs of seismic early warning twenty three sets of strong motion data from moderate earthquakes m 5 0 in the taiwan area are used to demonstrate the feasibility of this goal for earthquakes larger than ml 5 epicenters can be reliably determined in about 15 sec after the arrival of the p wave at the nearest station the earthquake magnitude m l cannot be determined in the same time frame due to incomplete recording of shear waves at some stations however the magnitude based on the first 10 sec of signal ml10 can be related to ml as follows ml 1 28 ml10 0 85 0 13 our results show that the real time strong motion system routinely used by the cen tral weather bureau can be used to determine epicenters and magnitudes in about 30 sec after occurrence of earthquakes in taiwan such information hopefully can be used to reduce damage to society

a climatology of anticyclones and blocking for the southern hemisphere abstract an automated procedure for locating and tracking high pressure centers is applied to 10 years of twice daily ecmwf analyses during 1980 89 to survey the behavior of anticyclones in the southern hemisphere anticyclones are concentrated in the 25 45 s band with preferred regions consistent with previous studies except in the new zealand nz south pacific sector where a double occurrence maximum noted in earlier studies was only weakly evident marked interannual variability was found in this region with the poleward branch of maximum occurrence south of 50 s present in only 3 out of 10 years mean central pressure maximized about 10 south of the time averaged ridge with highest values in winter anticyclones poleward of 50 s involve an anomalous breakdown of the westerlies with mean central pressures there 20 30 hpa higher than climatology highs tend to form and intensify in western regions of ocean basins and weaken and dissipate in the east of these oceans regions southeast of australi

statistics and dynamics of persistent anomalies abstract persistent anomalies with recurrent spatial patterns play an important role in the atmosphere s low frequency variability we establish a connection between statistical and dynamical methods of description and prediction of persistent anomalies this is done by computing and analyzing the empirical orthogonal functions eofs in a simple deterministic model on the one hand and in southern hemisphere geopotential heights on the other the dynamical model is governed by the fully nonlinear equivalent barotropic vorticity equation on the sphere with simplified forcing dissipation and topography model solutions exhibit persistent anomalies identifiable with blocked zonal and wave train anomalies in northern hemisphere atmospheric data flow structures similar to the patterns above occur as high variance eofs of this nonlinear model the southern hemisphere data we analyze consist in gridded daily maps of 500 mb heights from june 1972 to july 1983 two types of persistent anomalies appear in t

analysis of seafloor seismograms of the 2003 tokachi oki earthquake sequence for earthquake early warning 1 earthquake early warning eew algorithms estimate the magnitude of an underway rupture from the first few seconds of the p wave to allow hazard assessment and mitigation before the s wave arrival many large subduction zone earthquakes initiate 50 150 km offshore potentially allowing seafloor instruments sufficient time to identify large ruptures before the s waves reach land we tested an eew algorithm using accelerograms recorded offshore hokkaido in the region of the 2003 mw 8 1 tokachi oki earthquake and its aftershocks a wavelet transform of the first 4 s of the p wave concentrates information about earthquake magnitude from both waveform amplitude and frequency content we find that wavelets with support of a few seconds provide discriminants for eew that are both accurate enough to be useful and superior to peak acceleration or peak velocity additionally we observe a scaling of wavelet coefficient magnitude above mw 6 0 indicating that at least for the mainshock mw 8 1 and largest aftershock mw 7 1 the final size of a rupture could have been estimated from the initial portion of the seismogram

compaction in halite cemented carbonates the dawson bay formation middle devonian of saskatchewan canada halite impregnated carbonates in the dawson bay formation of saskatchewan lie between beds of halite and are buried to a depth of 1 km they exhibit two different diagenetic styles some resisted compaction and had high pre salt porosities others contain compaction broken fossils and pressure solution seams the uncompacted rocks together with the difficulty of explaining how halite cement could enter the dawson bay after overlying bedded halites were deposited suggest that halite cementation occurred early with only a few tens of metres of overburden early diagenetic compaction is suggested by the presence of unbroken displacive skeletal halite crystals which cross cut compaction structures and by the difficulty of explaining how 1 later compaction could occur in halite cemented rocks and 2 how pore fluids could be expelled after surrounding rocks lost their permeability the organic rich nature of many carbonates may explain why compaction was both early and extensive but this explanation fails to explain how similar compaction developed in horizons with lower organic contents chemical compaction may also have been enhanced by aragonite dissolution during seawater evaporation or brine dilution early chemical compaction in dawson bay carbonates indicates that compaction in other carbonates need not signify deep burial diagenesis neither can compaction be used indiscriminately to identify other diagenetic events as being of deep burial origin early halite cementation as in the dawson bay formation preserves carbonates at early diagenetic stages and may thus preserve geochemical information unmodified by later diagenesis

intraseasonal variability in south america during the cold season intraseasonal is variability in south america is analyzed during the cold season using 10 90 day bandpass filtered olr anomalies folr is variability explains a large percentage of variance with maximum values over paraguay northeastern argentina and southern brazil the leading pattern of folr as isolated from an eof analysis cold season is pattern csis is characterized by a monopole centered over southeastern south america sesa with a northwest southeast orientation csis induces a large modulation on daily precipitation anomalies especially on both wet spells and daily precipitation extremes which are favored during positive wet csis phases large scale olr anomalies over the tropical indian and west pacific oceans associated with csis exhibit eastward propagation along tropical latitudes in addition circulation anomalies in the southern hemisphere reveal the presence of an anticyclonic anomaly over antarctica with opposite sign anomalies in middle latitudes 10 days before csis is maximum as well as evidence of rossby wave like patterns positive precipitation anomalies in sesa are favored during wet csis phases by the intensification of a cyclonic anomaly located further south which is discernible over the southeastern pacific for at least 14 days before csis peaks the cyclonic anomaly evolution is accompanied by the intensification of an upstream anticyclonic anomaly which remains quasi stationary near the antarctica peninsula before the csis peak we speculate that the stationary behavior of the anticyclonic center is favored by a hemispheric circulation anomaly pattern resembling that associated with a negative southern annular mode phase and a wavenumber 3 4 pattern at middle latitudes

the boreal summer intraseasonal oscillation relationship between northward and eastward movement of convection the summertime intraseasonal oscillation iso is an important component of the south asian monsoon lagged regressions of intraseasonally filtered 25 80 days outgoing longwave radiation olr reveal that centers of convection move both northward and eastward from the central equatorial indian ocean subsequent to the initiation of an iso eastward movement of convection is also seen at indian subcontinent latitudes 10 8 208n based on the regression results the summertime iso convection signal appears as a band tilting northwestward with latitude and stretching from the equator to about 208n viewed along any meridian convection appears to propagate northward while equatorial convection propagates to the east to examine the robustness of the connection between eastward and northward movement individual isos are categorized and composited relative to the strength of the large scale eastward component of convection in the central equatorial indian ocean it is found that the majority of isos that exhibit northward movement onto the indian subcontinent 42 out of 54 isos or 78 also exhibit eastward movement into the western pacific ocean it is also found that when convection in the central indian ocean is not followed within 10 20 days by convection in the western pacific ocean 12 out of 54 isos or 22 the independent northward movement of convection in the indian ocean region is somewhat stunted the link between the eastward and northward movement of convection is consistent with an interpretation of the summertime iso in terms of propagating equatorial modes the northward moving portion of convection is forced by surface frictional convergence into the low pressure center of the rossby cell that is excited by equatorial iso convection a similar convergence pattern is seen for the northern winter iso but it does not generate poleward movement due to relatively cool ssts underlying the surface convergence

the pacific south american modes and tropical convection during the southern hemisphere winter abstract atmospheric circulation features and convection patterns associated with two leading low frequency modes in the southern hemisphere sh are examined in multiyear global reanalyses produced by ncep ncar and nasa dao the two leading modes referred to as the pacific south american psa modes are represented by the first two eof patterns the two patterns are in quadrature with each other and are dominated by wavenumber 3 in midlatitudes with large amplitudes in the pacific south american sector in the pacific anomalies in the subtropics and in the midlatitudes are opposite in phase taken together the two psa modes represent the intraseasonal oscillation in the sh with periods of roughly 40 days the evolution of the psa modes shows a coherent eastward propagation a composite analysis was conducted to study the evolution of tropical convection and the corresponding circulation changes associated with the psa modes outgoing longwave radiation olr anomaly composites during the mature phase

examination of scaling between earthquake magnitude and proposed early signals in p waveforms from very near source stations in a south african gold mine 1 we analyze near source seismograms recorded in a deep south african mine for scaling between signals early in p waveforms and the magnitude m of the events the data consist of recordings at 26 stations of 122 events with 1 5 0 implying that the final earthquake size is affected statistically by the initial rupture process if these correlations hold for larger earthquakes as suggested by other studies the early predominant period and peak displacement are useful for early warning systems

rossby wave propagation and teleconnection patterns in the austral winter abstract observational evidence of and theoretical support for the northern and southern hemisphere teleconnection patterns in the austral southern hemisphere winter are examined through an upper troposphere streamfunction teleconnectivity map and time lag cross correlation analysis using ecmwf initialized analysis 2oo hpa winds for the 11 june august periods from 1979 to 1989 as was previously found for the northern hemisphere winter the regions of strong teleconnectivity particularly in the winter hemisphere tend to he oriented in the zonal direction and coincide with the location of the major jet streams although equatorward propagation from the northern and southern hemispheres is observed little evidence of cross equatorial propagation has been found for comparison the response of a barotropic model linearized about a climatological 300 hpa june august time mean flow to localized forcing is determined it is found that the activity tends to be trapped inside each of the southern hemisphere

real time monitoring of moment magnitude by waveform inversion 1 an instantaneous measure of the moment magnitude mw of an ongoing earthquake is estimated from the moment rate function mrf determined in real time from available seismic data using waveform inversion integration of the mrf gives the moment function from which an instantaneousmw is derived by repeating the inversion procedure at regular intervals while seismic data are coming in we can monitor the evolution of seismic moment and mw with time the final size and duration of a strong earthquake can be obtained within 12 to 15 minutes after the origin time we show examples of mw monitoring for three large earthquakes at regional distances the estimated mw is only weakly sensitive to changes in the assumed source parameters depending on the availability of seismic stations close to the epicenter a rapid estimation of the mw as a prerequisite for the assessment of earthquake damage potential appears to be feasible

halite cementation and carbonate diagenesis of intra salt reservoirs from the late neoproterozoic to early cambrian ara group south oman salt basin late neoproterozoic to early cambrian carbonates of the ara group form important intra salt stringer reservoirs in the south oman salt basin differential loading of thick continental clastics above the six carbonate to evaporite cycles of the ara group led to the formation of salt diapirs encasing a predominantly self charging hydrocarbon system within partly highly overpressured carbonate bodies stringers these carbonates underwent a complex diagenetic evolution with one stage of halite cementation in a shallow early and another in a deep late burial environment early and late halite cements are defined by their microstructural relationship with solid bitumen the early phase of halite cementation is post dated by solid reservoir bitumen this phase is most pervasive towards the top of carbonate stringers where it plugs nearly all available porosity in facies with initially favourable poroperm characteristics bromine geochemistry revealed significantly higher bromine contents up to 280 p p m in the early halite compared with the late halite 173 p p m the distribution patterns and the high bromine contents of early halite are consistent with precipitation caused by seepage reflux of highly saturated brines during deposition of the overlying rock salt interval later in burial history relatively small quantities of early halite were dissolved locally and re precipitated as indicated by inclusions of streaky solid bitumen within the late halite cements late halite cement also seals fractures which show evidence for repeated reopening initially these fractures formed during a period of hydrothermal activity and were later reopened by a crack seal mechanism caused by high fluid overpressures porosity plugging by early halite cements affects the poroperm characteristics of the ara carbonates much more than the volumetrically less important late halite cement the formation mechanisms and distribution patterns of halite cementation processes in the south oman salt basin can be generalized to other petroliferous evaporite basins

predicting the macroseismic intensity from early radiated p wave energy for on site earthquake early warning in italy earthquake early warning systems eews are potentially effective tools for risk mitigation in active seismic regions the present study explores the possibility of predicting the macroseismic intensity within eew timeframes using the squared velocity integral iv2 measured on the early p wave signals a proxy for the p wave radiated energy of earthquakes this study shows that iv2 correlates better than the peak displacement measured on p waves with both the peak ground velocity and the housner intensity with the latter being recognized by engineers as a reliable proxy for damage assessment therefore using the strong motion recordings of the italian accelerometric archive a novel relationship between the parameter iv2 and the macroseismic intensity im has been derived the validity of this relationship has been assessed using the strong motion recordings of the istituto nazionale di geofisica e vulcanologia strong motion data and osservatorio sismico delle strutture databases as well as in the case of the mw 6 29 may 2012 emilia earthquake italy comparing the predicted intensities with the ones observed after a macroseismic survey our results indicate that p wave iv2 can become a key parameter for the design of on site eews capable of proving real time predictions of the im at target sites

test of a threshold based earthquake early warning method using japanese data most of existing earthquake early warning systems are regional or on site systems a new concept is the integration of these approaches for the definition of alert levels and the estimation of the earthquake potential damage zone pdz the key element of the method is the real time simultaneous measurement of initial peak displacement p d and period parameter c in a 3 s window after the first p wave arrival time at accelerometer stations located at increasing distances from the epicenter as for the on site approach the recorded values of p d and c are compared to threshold values which are set for a minimum magnitude m 6 and instrumental intensity i mm vii according to empirical regression analysis of strong motion data from different seismic regions at each recording site the alert level is assigned based on a decisional table with four entries defined by threshold values of the parameters p d and c a regional network of stations provides the event location and transmits the information about the alert levels recorded at near source stations to more distant sites before the arrival of the most destructive phase we present the results of performance tests of this method using ten m 6 japanese earthquakes that occurred in the period 2000 2009 and propose a very robust methodology for mapping the pdz in the first seconds after a moderate to large earthquake the studied cases displayed a very good matching between the rapidly predicted earthquake pdz inferred from initial p peak displacement amplitudes and the instrumental intensity map the latter being mapped after the event using peak ground velocity and or acceleration or from field macroseismic surveys

blocking over the south pacific and rossby wave propagation abstract atmospheric blocking events over the south pacific are investigated using a 39 yr record of 500 hpa height fields from the ncep ncar reanalysis dataset the analysis extends earlier work using a 16 yr record and confirms that the occurrence of blocking over the southeast pacific is strongly modulated by the enso cycle during austral spring and summer comparison of results at 500 hpa with the 300 hpa meridional wind component showed that blocking events are associated with large scale wave trains lying across the south pacific from the region of australia to southern south america similar wave trains are evident in both hemispheres in singular value decomposition analyses between 300 hpa meridional wind components and tropical pacific outgoing longwave radiation olr anomalies the hypothesis that the divergence associated with tropical olr anomalies forces an extratropical wave response that results in enhanced blocking over the southeast pacific was tested using a linearized barotropic vorti

development of an earthquake early warning system based on earthworm application to southwest iberia abstract the main aim of this study is to demonstrate the feasibility of an earthquake early warning system eews to warn of potentially destructive earthquakes in the cape san vicente sv and gulf of cadiz gc areas in the southwest iberian peninsula based on real time broadband stations existing in the region historic earthquakes in this region include the 1755 lisbon m w 8 5 and 1969 sv m w 7 8 events this study illustrates the design configuration and first results of an eews prototype based on the u s geological survey earthworm tools and developed at the institut cartografic i geologic de catalunya icgc system main functionalities are real time data acquisition processing p wave picking event detection earthquake hypocentral location and magnitude estimation from previously calculated peak displacement p d and predominant period c of the p wave signal data archiving and earthquake early warning dissemination the prototype was put into operation after a setup period during which several simulations were carried out to establish the optimal settings after the first year of operation one felt earthquake occurred in the area of study location and magnitude results are fairly good compared with the instituto geografico nacional ign catalog lead times obtained are on the order of tens of seconds for the majority of targets which are long enough to mitigate damage for a large area of the southern coasts of portugal and spain due to the gc and sv earthquakes preliminary results for this prototype demonstrate the possibility of a regional reliable and effective eews in southwest iberia

earthquake magnitude estimation from peak amplitudes of very early seismic signals on strong motion records 1 we show that the low pass filtered peak amplitudes of initial p and s wave seismic signals recorded in the vicinity of an occurring earthquake source correlates with the earthquake magnitude and may be used for real time estimation of the event size in seismic early warning applications the earthquake size can be therefore estimated using only a couple of seconds of signal from the p or s wave onsets i e while the rupture itself is still propagating and rupture dimension is far from complete we argue that dynamic stress release and or slip duration on the fault in the very early stage of seismic fracture scales both with the observed peak amplitude and with the elastic energy available for fracture propagation the probability that a fracture grows to a larger size should scale with the energy initially available citation zollo a m lancieri and s nielsen 2006 earthquake magnitude estimation from peak amplitudes of very early seismic signals on strong motion records geophys res lett 33 l23312 doi 10 1029 2006gl027795

origin of deformed halite hopper crystals pseudomorphic anhydrite cubes and polyhalite in alpine evaporites austria germany the alpine haselgebirge formation represents an upper permian to lower triassic evaporitic rift succession of the northern calcareous alps eastern alps although the rocksalt body deposits are highly tectonised consisting mainly of protocataclasites and mylonites of halite and mudrock the early diagenetic history can be established from non tectonised mudrock bodies cm sized euhedral halite hopper crystals formed as displacive cubes within mud just during shallow burial the crystals were deformed by subsequent compaction later migrating fluids led to the replacement of halite by anhydrite retaining the shapes of deformed halite cubes polyhalite formed from subsequent enhanced fluid migration mudrock provided water by dewatering while potassium and magnesium were dissolved from primary salt minerals when these fluids interacted with sulphates polyhalite precipitated 40ar 39ar analyses date the polyhalite from within the retaining shapes of deformed halite hopper shaped cubes from two localities to ca 235 232 ma middle triassic at this time ca 20 25 ma after sedimentation polyhalite crystallised at shallow levels

multiscale analysis of the summertime precipitation over the central andes precipitation over the central andes in south america exhibits a marked annual march with most of the rainfall concentrated during the austral summer season december february when the atmospheric circulation favors the uplifting of moist air from the lowlands to the east of the mountain range within its rainy season the central andes experiences week long rainy and dry episodes the large scale and local conditions during these episodes are investigated using satellite imagery reanalyzed atmospheric fields and in situ data despite the deep layer of conditional instability prevalent during most summertime afternoons deep convection can occur only on those days in which the mixing ratio within the local boundary layer exceeds some threshold 7gk g 21 yielding saturation of near surface air parcels rising more than 600 m above ground convective cloudiness anomalies over the central andes extend southeastward and tend to be concurrent with anomalies of opposite sign over the eastern part of the continent rainy dry episodes are also associated with anticyclonic cyclonic anomalies centered over subtropical south america that extend through the depth of the troposphere accompanied by easterly westerly wind anomalies over the central andes these anomalies are presumably forced by planetary waves originating in the southern hemisphere extratropics to gain insight into the regional processes linking the large scale and local conditions the pennsylvania state university national center for atmospheric research mesoscale model version 5 2 was used to simulate contrasting rainy and dry episodes the most marked and relevant differences are the strength and extent of diurnally varying flow over the eastern slope of the andes during the rainy simulation strong easterly winds reach the upper part of the slope by midmorning initiating an intrusion of warm and moist air high ue air originating in the eastern lowlands into the central andes in the dry case the moisture transport from the east is restricted to the eastern slope of the andes and the central andes is flooded by low ue air from the western foothills that cannot support deep convection even in the presence of localized updrafts the momentum balance based on the model output indicates that turbulent momentum mixing from aloft determined by the large scale anomalies of the upper level flow into the convective boundary layer is the leading term causing the differences in the daytime upslope flow and hence moisture transport over the upper part of the eastern side of the andes between rainy and dry simulations