spectroscopic evidence for a lava fountain driven by previously accumulated magmatic gas the eruption of mount etna in 2000 was notable for an exceptional series of 64 periodic lava fountains propelling lava fragments to heights of up to 900 metres it has been difficult to determine which of two suggested sources of power gas release from the magma itself during its rapid ascent or a build up of pressure from gas accumulated at depth is the driving force for these dramatic jets but one of the etna fountains provided volcanologists with the opportunity to use remote sensing not that remote see picture on the following page to determine the infrared spectra of the gas phase this revealed the chemical composition of the gas that powered this fountain as consistent with an origin in an accumulated gas layer lava fountains are spectacular continuous gas jets propelling lava fragments to heights of several hundred metres which occasionally occur during eruptions of low viscosity magmas1 2 3 4 5 whether they are generated by the effervescent disruption of fast rising bubbly melt2 3 4 5 or by the separate ascent of a bubble foam layer accumulated at depth6 7 still remains a matter of debate8 no field measurement has yet allowed firm discrimination between these two models a key insight into the origin of lava fountains may be gained by measuring the chemical composition of the driving gas phase this composition should differ markedly depending on whether the magma degassing occurs before or during eruption9 10 here we report the analysis of magmatic gas during a powerful 250 600 m high lava fountain measured with fourier transform infrared spectroscopy11 12 13 14 on mount etna sicily the abundances of volcanic gas species determined from absorption spectra of lava radiation reveal a fountain gas having higher co2 s and s cl ratios than other etnean emissions14 15 16 17 18 and which cannot derive from syn eruptive bulk degassing of etna basalt19 20 instead its composition suggests violent emptying of a gas bubble layer previously accumulated at about 1 5 km depth below the erupting crater

effect of variable bathymetry on the amplitude of teleseismic tsunamis a ray tracing experiment we apply surface wave ray tracing techniques to tsunami propagation in an ocean of variable depth because tsunami velocities are proportional to the square root of the depth of the water column the juxtaposition of oceanic plateaux and basins generates strong lateral velocity gradients and bathymetric features can act as lenses focusing or defocusing the tsunami waves we present a reconstruction of the tsunami wave field from the great chilean earthquake of 1960 an order of magnitude computation based on the concept of ray density provides qualitative agreement with observations at several sites in the pacific ocean we also demonstrate the possibility of using reciprocal maps to identify tsunamigenic zones that present particular danger for a given receiving shore

evolution of dike opening during the march 2011 kamoamoa fissure eruption kīlauea volcano hawai i 1 the 5 9 march 2011 kamoamoa fissure eruption along the east rift zone of k lauea volcano hawai i followed months of pronounced inflation at k lauea summit we examine dike opening during and after the eruption using a comprehensive interferometric synthetic aperture radar insar data set in combination with continuous gps data we solve for distributed dike displacements using a whole k lauea model with dilating rift zones and possibly a deep decollement modeled surface dike opening increased from nearly 1 5 m to over 2 8 m from the first day to the end of the eruption in agreement with field observations of surface fracturing surface dike opening ceased following the eruption but subsurface opening in the dike continued into may 2011 dike volumes increased from 15 to 16 to 21 million cubic meters mcm after the first day eruption end and 2 months following respectively dike shape is distinctive with a main limb plunging from the surface to 2 3 km depth in the up rift direction toward k lauea s summit and a lesser projection extending in the down rift direction toward pu u at 2 km depth volume losses beneath k lauea summit 1 7 mcm and pu u 5 6 mcm crater relative to dike plus erupted volume 18 3 mcm yield a dike to source volume ratio of 2 5 that is in the range expected for compressible magma without requiring additional sources inflation of k lauea s summit in the months before the march 2011 eruption suggests that the kamoamoa eruption resulted from overpressure of the volcano s magmatic system

crustal thickness map of the chinese mainland from teleseismic receiver functions abstract we present a new crustal thickness map of the chinese mainland and adjacent areas based on a compilation of previously published data more than 1900 estimates of crustal thickness from receiver function studies were collected and the weighted averages were used to develop a contour map of crustal thickness beneath the chinese mainland the combined dataset provided good coverage especially over eastern and central china and our analysis revealed crustal thickness variations of the chinese mainland with considerably more detail than in previous models our crustal thickness map shows a large variation from a thickness of less than 30 km in the mesozoic basin of eastern china to over 80 km in the tibetan plateau the thickest crust was found in central tibet while the thinnest continental crust was observed beneath eastern china normal to slightly thick crust 38 51 km was found for the stable precambrian basins and orogenic belts comparison between our model and other models reveals that the models share similar large scale and smaller scale features over large portions of eastern china where the data coverage is good however large differences up to 25 km in crustal thickness occur in areas with complex crustal structure or poor data coverage we also evaluated the quality of previous models by comparing them with our newly compiled point observations of crustal thickness

coseismic slip and afterslip of the great mw 9 15 sumatra andaman earthquake of 2004 we determine coseismic and the first month postseismic deformation associated with the sumatra andaman earthquake of 26 december 2004 from near field global positioning system gps surveys in northwestern sumatra and along the nicobar andaman islands continuous and campaign gps measurements from thailand and malaysia and in situ and remotely sensed observations of the vertical motion of coral reefs the coseismic model shows that the sunda subduction mega thrust ruptured over a distance of about 1500 km and a width of less than 150 km releasing a total moment of 6 7 7 0 10 22 n m equivalent to a magnitude m w 9 15 the latitudinal distribution of released moment in our model has three distinct peaks at about 4 n 7 n and 9 n which compares well to the latitudinal variations seen in the seismic inversion and of the analysis of radiated t waves our coseismic model is also consistent with interpretation of normal modes and with the amplitude of very long period surface waves the tsunami predicted from this model fits rela tively well the altimetric measurements made by the jason and topex satellites neither slow nor delayed slip is needed to explain the normal modes and the tsunami wave the near field geodetic data that encompass both coseismic deformation and up to 40 days of postseismic deformation require that slip must have continued on the plate interface after the 500 sec long seismic rupture the postseismic geodetic moment of about 2 4 10 22 nm mw 8 8 is equal to about 30 5 of the coseismic moment release evolution of postseismic deformation is consistent with rate strengthening frictional afterslip online material summary of geodetic data used in this study

magma flow between summit and pu u ō ō at klauea volcano hawai i 1 volcanic eruptions are often accompanied by spatiotemporal migration of ground deformation a consequence of pressure changes within magma reservoirs and pathways we modeled the propagation of pressure variations through the east rift zone erz of klauea volcano hawai i caused by magma withdrawal during the early eruptive episodes 1983 1985 of the ongoing pu u kupaianaha eruption eruptive activity at the pu u vent was typically accompanied by abrupt deflation that lasted for several hours and was followed by a sudden onset of gradual inflation once the eruptive episode had ended similar patterns of deflation and inflation were recorded at klauea s summit approximately 15 km to the northwest albeit with time delays of hours these delay times can be reproduced by modeling the spatiotemporal changes in magma pressure and flow rate within an elastic walled dike that traverses klauea s erz key parameters that affect the behavior of the magma dike system are the dike dimensions the elasticity of the wall rock the magma viscosity and to a lesser degree the magnitude and duration of the pressure variations themselves combinations of these parameters define a transport efficiency and a pressure diffusivity which vary somewhat from episode to episode resulting in variations in delay times the observed variations in transport efficiency are most easily explained by small localized changes to the geometry of the magma pathway

contrasting patterns of vesiculation in low intermediate and high hawaiian fountains a case study of the 1969 mauna ulu eruption abstract hawaiian style eruptions or hawaiian fountains typically occur at basaltic volcanoes and are sustained weakly explosive jets of gas and dominantly coarse juvenile ejecta dense spatter to delicate reticulite almost the entire range of styles and mass eruption rates within hawaiian fountaining occurred during twelve fountaining episodes recorded at mauna ulu k lauea between may and december 1969 such diversity in intensity and style is controlled during magma ascent by many processes that can be constrained by the size and shape of vesicles in the 1969 pyroclasts this paper describes pyroclast vesicularity from high intermediate and low fountaining episodes with eruption rates from 0 05 to 1 3 10 6 m 3 h 1 as each eruptive episode progressed magma ascent slowed in and around the vent system offering extended time for bubbles to grow and coalesce late ejected pyroclasts are thus characterized by populations of fewer and larger vesicles with relaxed shapes this progression continued in the intervals between episodes after termination of fountain activity the time scale for this process of shallow growth coalescence and relaxation of bubbles is typically tens of hours rims and cores of pumiceous pyroclasts from moderate to high fountaining episodes record a second post fragmentation form of vesicle maturation partially thermally insulated pyroclasts can have internal bubble populations evolve more dynamically with continued growth and coalescence on a time scale of only minutes during transport in the fountains reticulite which formed in a short lived fountain 540 m in height underwent late short lived bubble nucleation followed by rapid growth of a uniform bubble population in a thermally insulated fountain and quenched at the onset of permeability before significant coalescence these contrasting patterns of shallow degassing and outgassing were the dominant controls in determining both the form and duration of fountaining episodes at mauna ulu and probably for many other hawaiian style eruptions

terrasar x interferometry reveals small scale deformation associated with the summit eruption of kīlauea volcano hawai i 1 on 19 march 2008 a small explosive eruption at the summit of k lauea volcano hawai i heralded the formation of a new vent along the east wall of halema uma u crater in the ensuing years the vent widened due to collapses of the unstable rim and conduit wall some collapses impacted an actively circulating lava pond and resulted in small explosive events we used synthetic aperture radar data collected by the terrasar x satellite a joint venture between the german aerospace center dlr and eads astrium to identify and analyze small scale surface deformation around the new vent during 2008 2012 lidar data were used to construct a digital elevation model to correct for topographic phase allowing us to generate differential interferograms with a spatial resolution of about 3 m in k lauea s summit area these interferograms reveal subsidence within about 100 m of the rim of the vent small baseline subset time series analysis suggests that the subsidence rate is not constant and over time may provide an indication of vent stability and potential for rim and wall collapse information with obvious hazard implications the deformation is not currently detectable by other space or ground based techniques

double jeopardy concurrent arrival of the 2004 sumatra tsunami and storm generated waves on the atlantic coast of the united states and canada 1 a detailed analysis of over one hundred tide gauge records from the atlantic coast of north america reveals that the arrival of the 26 december 2004 sumatra tsunami on this coast coincided with the presence of tsunami like waves being generated by a major storm tracking northward along the eastern seaboard of the united states according to the tide gauge records waves from the two events coalesced along the shores of maine and nova scotia on 27 december where they produced damaging waves with heights in excess of 1 m tsunami waves were identified in almost all outer tide gauges from florida to nova scotia with maximum tsunami heights for the northern regions estimated to be 32 39 cm in the south maximum tsunami wave heights were in the range of 15 to 33 cm

effects of bathymetry on tsunami propagation application of ray tracing to tsunamis ray tracing of seismic surface waves is applied to tsunami propagation to examine bathymetric effect along its propagation path computations are made for trans pacific tsunamis and for near field tsunamis in the japan sea for tsunamis across the pacific ocean the comparison to a uniform ocean shows that focusing and defocusing due to bathymetry are significant for some combinations of source and receiver for example the refraction of rays is predominant at the east pacific rise for the tsunami from chile the tsunamis in the japan sea are strongly affected by the shallow yamato rise the predicted arrival time and amplitude distribution generally agree with the observations from an actual tsunami since the computation can be made very quickly the method is useful for preliminary analysis of tsunami propagation such as in an operational warning system or in the determination of computational area for finite difference computation

history and features of trans oceanic tsunamis and implications for paleo tsunami studies abstract far field tsunamis and their features as well as methods to quantify trans oceanic tsunamis are reviewed with examples of instrumental and historical data tsunamis from the 1854 nankai earthquakes the 1946 aleutian tsunami earthquake the 1960 and 2010 chile earthquakes as well as the 2011 tohoku earthquake were recorded around the pacific ocean the 1883 krakatoa volcanic eruption caused volcanic tsunami in the indian ocean and meteotsunami in the pacific ocean the 2004 indian ocean tsunami was also recorded in the pacific ocean when a tsunami amplitude is larger than that of ocean tides which usually requires the parent earthquake to be gigantic mw 9 it can cause damage and may be historically documented the trans pacific tsunamis described in historical documents include those from the 1700 cascadia earthquake the 1730 1751 1837 and 1877 earthquakes off chile and the 1687 and 1868 earthquakes off peru the tsunami record in japan from the 1586 peru earthquakes was found to be incorrect and should be discounted the tsunami magnitude scale relates the tsunami heights to the earthquake size tsunami travel time can be computed from actual bathymetry and the tsunami ray tracing provides relative amplitudes due to focusing defocusing caused by irregular bathymetry numerical computations from fault models produce tsunami amplitudes and waveforms and indicate strong directivity due to strike of fault or orientation of subduction zones far field tsunamis are often long lasting due to multiple reflections across the basin or on continental shelf or due to resonance in bays harbors these features would provide important criteria to estimate tsunami sources from paleo tsunami data

potential mass movements on the palinuro volcanic chain southern tyrrhenian sea italy and consequent tsunami generation abstract the palinuro volcanic chain pvc is located about 80 km offshore the campania region italy in the southern sector of the tyrrhenian sea the chain consists of 15 volcanic edifices aligned in an e w direction with two distinct major seamounts palinuro and glabro they cover a 90 km long and 20 km wide area with a present day volume of 2700 km3 palinuro volcanism emplaced between 0 8 and 0 3 ma although shallow seismicity and hydrothermalism indicate an ongoing volcanic activity a geomorphological analysis of the volcanic chain and data from a multichannel seismic profile reveal large volumes of buried chaotic material suggesting gravity mass sliding from the volcano flanks and slide scars a stability analysis of the palinuro flanks has been carried out to determine the sectors potentially prone to sliding in case of shallow volcanic earthquakes landslides are simulated by adopting a scenario based approach tsunamis induced by these mass movements and their propagation across the tyrrhenian sea are modeled results suggest that shallow earthquakes m 4 6 4 8 are able to destabilize the flanks of the volcanic chain generating slope failures sliding volumes in the order of 1 5 km3 and 2 4 km3 may induce waves as high as 1 5 and 6 m respectively along the peri tyrrhenian coast our results underline the need for further investigations on the stability of the submarine volcanoes of the tyrrhenian basin these volcanoes are still poorly known although their instability could trigger large tsunamis along the southern italy coastal sectors our recommendation is that multiparamertic monitoring networks on pvc and periodic oceanic cruises should be put into action and further that a systematic evaluation of the tsunami hazard related to possible sliding phenomena on the flanks of the tyrrhenian seamounts should be performed

the 2004 sumatra tsunami in the southeastern pacific ocean new global insight from observations and modeling the 2004 sumatra tsunami was an unprecedented global disaster measured throughout the world oceans the present study focused on a region of the southeastern pacific ocean where the westward circumferentially propagating tsunami branch converged with the eastward branch based on data from fortuitously placed chilean dart 32401 and tide gauges along the coast of south america by comparison of the tsunami and background spectra we suppressed the influence of topography and reconstructed coastal spectral ratios that were in close agreement with a ratio at dart 32401 and spectral ratios in other oceans findings indicate that even remote tsunami records carry spectral source signatures birth marks the 2004 tsunami waves were found to occupy the broad frequency band of 0 25 10 cph with the prominent ratio peak at period of 40 min related to the southern fast slip source domain this rupture hot spot of 350 km was responsible for the global impact of the 2004 tsunami data from dart 32401 provided validation of model results the simulated maximum tsunami wave height of 2 25 cm was a conservative approximation to the measured height of 2 05 cm the computed tsunami travel time of 25 h 35 min to dart 32401 although 20 min earlier than the actual travel time provided a favorable result in comparison with 24 h 25 min estimated from classical kinematic theory the numerical simulations consistently reproduced the wave height changes observed along the coast of south america including local amplification of tsunami waves at the northern stations of arica 72 cm and callao 67 cm

lava fountain heights at pu u o o kilauea hawaii indicators of amount and variations of exsolved magma volatiles we review the factors determining lava fountain heights in hawaiian style basaltic eruptions such as those occurring during the recent series of eruptive episodes at the pu u o o vent east rift zone of kilauea volcano hawaii numerical solutions to the equations describing the fluid dynamics of such eruptions predict that lava fountain heights which are indicators of the velocity of magmas in vents should be controlled much more strongly by amounts of exsolved volatiles than by any other factors the next most important factor is the width of the conduit system which determines frictional losses and can be characterized by the volume flux of magma the diameter of the surface vent required to accommodate a given discharge i e instantaneous volume rate of eruption is also a function of exsolved magma volatile content but is less dependent on this factor than is the fountain height we simulate fountain heights for typical discharges at pu u o o and find implied exsolved gas contents very close to those determined by other methods the corresponding predicted vent diameters are comparable with and somewhat smaller than the observed diameter of the pu u o o vent the discrepancy is probably a consequence of processes occurring in the lava pond which is present over the vent during eruptions the variation of fountain height with time during eruptive episodes can be used as a measure of changing exsolved magma volatile content which can be related to processes occurring in the subsurface dike system

the 2009 samoan and 2010 chilean tsunamis recorded on the pacific coast of russia two remote tsunamis were recorded on the pacific coast of russia a relatively weak samoan tsunami of september 29 2009 and a much stronger chilean tsunami of february 28 2010 in the area of the south kuril islands records were obtained using autonomous bottom pressure gauges of the institute of marine geology and geophysics imgg additionally for the oceanic coast of the kamchatka peninsula paramushir and bering islands we used data transmitted from coastal tide gauges of the russian tsunami warning service tws the maximum trough to crest heights of the samoan tsunami were about 30 40 cm and were recorded about 3 h after the first tsunami arrival the maximum chilean tsunami trough to crest wave heights were 218 cm at severo kurilsk 187 cm at tserkovnaya bay shikotan island and 140 cm at khodutka bay kamchatka peninsula the time between first and maximum waves reached 4 h strong sea level oscillations for both events range for a long time about 15 17 h the samoan tsunami induced high frequency oscillations a considerable increase in spectral energy in the tsunami spectrum was observed at periods of 4 20 min in contrast the chilean tsunami induced low frequency oscillations the dominant periods were 30 80 min a probable reason for these differences is the different extensions of the source areas the chilean source was much larger than the samoan source and the different energy radiation directions from the sources local topography resonant effects were the main reason of well expressed peaks in power spectra in different areas with a period of 10 min khodutka bay 19 20 min malokurilskaya and tserkovnaya bays 29 min krabovaya inlet and 43 min avachinskaya guba and nikolskoe

waves of bubbles in basaltic magmas and lavas initially homogeneous suspensions of bubbles in basaltic magmas and lava flows may become unstable and form rising waves or layers of bubbles we derive a set of model equations for the two phase bubble liquid system and present the results of a linear stability analysis and numerical simulations periodic vesicle layers are preserved in columbia liver flows with a spacing of 1 m the prediction of the stability analysis combined with a simple model for solidification of the lava suggests that vesicle layers may represent waves of bubbles formed within the flow the spacing of layers is determined by a balance between the growth of bubbles and hydrodynamic self diffusion vesicular layers preserved in columbia liver flows may thus form by hydrodynamic processes and do not require the repeated injection of fresh volatile rich magma or a periodic nucleation of bubbles waves of bubbles may also develop in magma chambers and conduits and could play a role in eruption dynamics

the el salvador and philippines tsunamis of august 2012 insights from sea level data analysis and numerical modeling we studied two tsunamis from 2012 one generated by the el salvador earthquake of 27 august mw 7 3 and the other generated by the philippines earthquake of 31 august mw 7 6 using sea level data analysis and numerical modeling for the el salvador tsunami the largest wave height was observed in baltra galapagos islands 71 1 cm located about 1 400 km away from the source the tsunami governing periods were around 9 and 19 min numerical modeling indicated that most of the tsunami energy was directed towards the galapagos islands explaining the relatively large wave height there for the philippines tsunami the maximum wave height of 30 5 cm was observed at kushimoto in japan located about 2 700 km away from the source the tsunami governing periods were around 8 12 and 29 min numerical modeling showed that a significant part of the far field tsunami energy was directed towards the southern coast of japan fourier and wavelet analyses as well as numerical modeling suggested that the dominant period of the first wave at stations normal to the fault strike is related to the fault width while the period of the first wave at stations in the direction of fault strike is representative of the fault length

the dual source region for the 2004 sumatra tsunami 1 wave arrival times obtained from coastal tide gage and satellite altimetry records for the indian ocean are used to delineate the source region for the december 26 2004 sumatra tsunami findings define a curved 250 km wide 1000 km long tsunami source region centered over the sunda subduction zone which closely matches the seismic source estimated from broadband geophysical data imbedded in this general region are hot spots associated with the southern fast slip and northern slow slip domains which served as distinct source areas for the destructive waves that inundated the coast of the indian ocean

n view reconstruction a new method for morphological modelling and deformation measurement in volcanology abstract we present a method of reconstructing volcanic morphology using multiple digital views n view captured at different angles around an object this approach uses recent advances in the field of computer vision to provide accurate 3 d measurements of volcanic surfaces videogrammetry digital image reconstruction is used as it is best adapted to numerical processing the method is tested and now used in the laboratory on analogue volcanic cones the method begins with calibrating the camera and finding image positions using an accurate n view calibration method this is done by estimating internal and external parameters of the camera using several views of a specially constructed calibration target the n view reconstruction of the real object is then done by iteratively deforming an initial theoretical model of the surface laboratory tests show that reconstruction accuracy is about 10 4 m for a distance between the object and the camera of 0 5 m and is potentially several orders of magnitude higher for surfaces of finer texture and using higher precision sensors this is easily high enough to be useful for the accuracy required for morphological studies it is also sufficient for monitoring most types of volcano deformation the technique has the potential to detect morphology changes of the order of mm use of the method in the field requires a slightly different approach from that in the laboratory textures and lighting are more variable and the sensor and ground control point location and model calibration must be done differently we provide case studies from laboratory tests and qualitative image analysis for two field cases piton de la fournaise indian ocean and santaguito guatemala these illustrate the technique s potential and explore problems of field application using current sensors the method has the potential to provide sufficient precision for fine mm cm scale reconstruction and will represent a valuable simple and flexible tool when compared with classical stereophotogrammetry techniques

time averaged discharge rate of subaerial lava at kīlauea volcano hawai i measured from tandem x interferometry implications for magma supply and storage during 2011 2013 differencing digital elevation models dems derived from terrasar add on for digital elevation measurements tandem x synthetic aperture radar imagery provides a measurement of elevation change over time on the east rift zone ezr of k lauea volcano hawai i the effusion of lava causes changes in topography when these elevation changes are summed over the area of an active lava flow it is possible to quantify the volume of lava emplaced at the surface during the time spanned by the tandem x data a parameter that can be difficult to measure across the entirety of an 100 km2 lava flow field using ground based techniques or optical remote sensing data based on the differences between multiple tandem x derived dems collected days to weeks apart the mean dense rock equivalent time averaged discharge rate of lava at k lauea between mid 2011 and mid 2013 was approximately 2 m3 s which is about half the long term average rate over the course of k lauea s 1983 present erz eruption this result implies that there was an increase in the proportion of lava stored versus erupted a decrease in the rate of magma supply to the volcano or some combination of both during this time period in addition to constraining the time averaged discharge rate of lava and the rates of magma supply and storage topographic change maps derived from space based tandem x data provide insights into the four dimensional evolution of k lauea s erz lava flow field tandem x data are a valuable complement to other space air and ground based observations of eruptive activity at k lauea and offer great promise at locations around the world for aiding with monitoring not just volcanic eruptions but any hazardous activity that results in surface change including landslides floods earthquakes and other natural and anthropogenic processes

odessa tsunami of 27 june 2014 observations and numerical modelling on 27 june a 1 2 m high wave struck the beaches of odessa the third largest ukrainian city and the neighbouring port town illichevsk northwestern black sea throughout the day prominent seiche oscillations were observed in several other ports of the black sea tsunamigenic synoptic conditions were found over the black sea stretching from romania in the west to the crimean peninsula in the east intense air pressure disturbances and convective thunderstorm clouds were associated with these conditions right at the time of the event a 1 5 hpa air pressure jump was recorded at odessa and a few hours earlier in romania we have utilized a barotropic ocean numerical model to test two hypotheses 1 a tsunami like wave was generated by an air pressure disturbance propagating directly over odessa experiment 1 2 a tsunami like wave was generated by an air pressure disturbance propagating offshore approximately 200 km to the south of odessa and along the shelf break experiment 2 both experiments decisively confirm the meteorological origin of the tsunami like waves on the coast of odessa and imply that intensified long ocean waves in this region were generated via the proudman resonance mechanism while propagating over the northwestern black sea shelf the odessa tsunami of 27 june 2014 was identified as a beach meteotsunami similar to events regularly observed on the beaches of florida usa but different from the harbour meteotsunamis which occurred 1 3 days earlier in ciutadella baleares spain mazara del vallo sicily italy and vela luka croatia in the mediterranean sea despite that they were associated with the same atmospheric system moving over the mediterranean black sea region on 23 27 june 2014

the 1983 86 pu u o o eruption of kilauea volcano hawaii a study of dike geometry and eruption mechanisms for a long lived eruption abstract the 1983 1986 pu u o o eruption of kilauea volcano had a very distinctive episodic character which later changed to steady state activity in this paper we present a physical model of episodic activity which explains the process largely in terms of non uniform magma cooling and yield strength development resulting from variable dike width the model is applied to the pu u o o data set and shows that to explain the pressure variations within the summit magma reservoir and the patterns of summit deflation a yield strength of 80 to 200 pa needs to be developed this corresponds to a temperature decrease in the magma of 10 15 c consistent with temperature variations measured in the erupted lavas the model stimulates the variation in volume flux as a function of time through the eruption and produces results which agree well with observed patterns of magma movement gradual evolution of the dike system through the eruptive series is explained by progressive widening of its narrowest sections the loss of the episodic character and the transition to continuous activity is explained by a slight change in the thermal efficiency of the system the change in pattern of gas release from lava fountaining to gas pistoning and strombolian activity which accompanied the change from episodic activity to steady state eruption results from the reduction in magma flow rate at shallow levels in the dike system however we demonstrate that continuous eruptions do not inherently lack lava fountains higher magma supply rates and thus higher flow velocities would allow fountaining to occur during continuous eruption we demonstrate that episodic eruptions result from a fine balance between the effects of cooling of magma within the dike and the generation of pressure within the magma reservoir and thus that thermally episodic eruptions reflect a middle ground between short lived fissure eruptions in which magma cooling dominates and continuous eruption in which cooling is minimised the initial few months of an eruption being critical to establishing the thermal viability of the dike system

seismology speed and size of the sumatra earthquake we now have a clearer picture of the seismic features of last year s gigantic event our seismological results reveal that indonesia s devastating sumatra andaman earthquake on 26 december 2004 was 2 5 times larger than initial reports suggested second only to the 1960 chilean earthquake in recorded magnitude they indicate that it slowly released its energy by slip along a 1 200 km fault generating a long rupture that contributed to the subsequent tsunami now that the entire rupture zone has slipped the strain accumulated from the subduction of the indian plate beneath the burma microplate has been released and there is no immediate danger of a similar tsunami being generated on this part of the plate boundary although large earthquakes on segments to the south still present a threat

energy decay of the 2004 sumatra tsunami in the world ocean the catastrophic indian ocean tsunami generated off the coast of sumatra on 26 december 2004 was recorded by a large number of tide gauges throughout the world ocean this study uses gauge records from 173 sites to examine the characteristics and energy decay of the tsunami waves from this event in the indian atlantic and pacific oceans findings reveal that the decay e folding time of the tsunami wave energy within a given oceanic basin is not uniform as previously reported but depends on the absorption characteristics of the shelf adjacent to the coastal observation site and the time for the waves to reach the site from the source region in general the decay times for island and open ocean bottom stations are found to be shorter than for coastal mainland stations decay times for the 2004 sumatra tsunami ranged from about 13 h for islands in the indian ocean to 40 45 h for mainland stations in the north pacific

episode 49 of the pu u o o kupaianaha eruption of kilauea volcano breakdown of a steady state eruptive era the pu u o o kupaianaha eruption 1983 present is the longest lived rift eruption of either kilauea or neighboring mauna loa in recorded history the initial fissure opening in january 1983 was followed by three years of episodic fire fountaining at the pu u o o vent on kilauea s east rift zone 19km from the summit episodes 4 47 these spectacular events gave way in july 1986 to five and a half years of nearcontinuous low level effusion from the kupaianaha vent 3km to the cast episode 48 a 49th episode began in november 1991 with the opening of a new fissure between pu u o o and kupaianaha this three week long outburst heralded an era of more erratic eruptive behavior characterized by the shut down of kupaianaha in february 1992 and subsequent intermittent eruption from vents on the west flank of pu u o o episodes 50 and 51 the events occurring over this period are due to progressive shrinkage of the rift zone reservoir beneath the eruption site and had limited impact on eruption temperatures and lava composition

vesiculation of basaltic magma during eruption vesicle size distributions in vent lavas from the pu9u9o9o kupaianaha eruption of kilauea volcano are used to estimate nucleation and growth rates of h 2 o rich gas bubbles in basaltic magma nearing the earth9s surface 120 m depth by using well constrained estimates for the depth of volatile exsolution and magma ascent rate nucleation rates of 35 9 events cm 3 s 1 and growth rates of 3 2 x 10 4 cm s are determined directly from size distribution data the results are consistent with diffusion controlled growth as predicted by a parabolic growth law this empirical approach is not subject to the limitations inherent in classical nucleation and growth theory and provides the first direct measurement of vesiculation kinetics in natural settings in addition perturbations in the measured size distributions are used to examine bubble escape accumulation and coalescence prior to the eruption of magma

the great sumatra andaman earthquake of 26 december 2004 the two largest earthquakes of the past 40 years ruptured a 1600 kilometer long portion of the fault boundary between the indo australian and southeastern eurasian plates on 26 december 2004 seismic moment magnitude mw 9 1 to 9 3 and 28 march 2005 mw 8 6 the first event generated a tsunami that caused more than 283 000 deaths fault slip of up to 15 meters occurred near banda aceh sumatra but to the north along the nicobar and andaman islands rapid slip was much smaller tsunami and geodetic observations indicate that additional slow slip occurred in the north over a time scale of 50 minutes or longer

a plinian treatment of fallout from hawaiian lava fountains a new model is presented which simulates the dispersal and deposition of material from a hawaiian eruption column the model treats the hawaiian column as a coarse grained plinian column and uses a modified version of the wilson and walker wilson l walker g p l 1987 explosive volcanic eruptions vi ejecta dispersal in plinian eruptions the control of eruption conditions and atmospheric properties geophys j r astron soc 89 657 679 plinian pyroclast dispersal model to simulate the fall out of material during a hawaiian eruption the model results are found to be in good agreement with independent estimates of various parameters made for the 1959 kilauea iki eruption of kilauea volcano the close agreement between the model results and these independent estimates shows that dynamically hawaiian eruptions are indistinguishable from plinian eruptions the major differences in the styles and deposits of these two types of eruptions are accounted for by differences in the mass fluxes and gas contents of the erupting magmas and most fundamentally by differences in the grainsize distribution of the erupted clasts plume heights predicted by the model are greater than those found for previous models of hawaiian eruptions this is because previous models did not allow for the progressive fall out of particles from the plume and more importantly made no correction for the velocity disequilibrium between gas and clasts when the grainsize distribution is coarse

low cost volcano deformation monitoring optical strain measurement and application to mount st helens data summary this paper describes an innovative method of volcano deformation measurements applied to camera images taken from the 2004 2008 eruption period at mount st helens dome growth was thought to be characterized by sustained near linear rates of a solid dacite plug through spatial digital image correlation dic analysis of the camera images new evidences arise that the deformation and strain rate of the spine was more complex dic yielded cumulative and incremental displacements strain and shear planes at decimetre resolution it was found that dome extrusion rates are highly non linear decelerating prior to partial collapse followed by a pronounced dome extrusion increase and direction change associated processes have been identified through dic such as shallow landslides and reworking of talus apron material the work highlights the strengths of camera strain monitoring and illustrates that dome growth and collapse is a very dynamic process complexly interplaying with the surrounding

tsunami source of the 2004 sumatra andaman earthquake inferred from tide gauge and satellite data tsunami source of the 2004 sumatra andaman earthquake was esti mated from a joint inversion of tsunami waveforms recorded on tide gauges and sea surface heights captured by satellite altimetry measurements the earthquake the largest in the past 40 years caused devastating tsunami damage to countries around the indian ocean but the tsunami source in particular its northern end was not well resolved although aftershocks and crustal deformation extended from off north western sumatra island through the nicobar islands to the andaman islands some seismic wave analyses indicated a shorter source length several hundred kilometers we used tsunami waveforms recorded at 12 tide gauge stations around the source and the sea surface heights measured by three satellites jason1 topex poseidon and envisat we numerically computed tsunami propagation using realistic bathym etry more than 66 000 depth points were digitized from nautical charts and combined with the etopo2 data inversion of satellite data indicates that the tsunami source extended to the andaman islands with a total length of 1 400 km but such a model produces much larger tsunami waveforms than observed at indian tide gauge stations inversion of tide gauge records and the joint inversion indicate that the tsunami source was about 900 km long the largest slip about 13 to 25 m was located off sumatra island and the second largest slip up to 7 m near the nicobar islands the slip distribution is similar for different rupture velocities and rise times with a slow velocity of 1 km sec and a rise time of 3 min yielding the largest variance reduction

refir a multi parameter system for near real time estimates of plume height and mass eruption rate during explosive eruptions abstract meaningful forecasting of the atmospheric concentration and ground accumulation of volcanic ash during explosive eruptions requires detailed knowledge of the eruption source parameters however due to the large uncertainties in observations and limitations of current models used to make inferences from these monitoring an ongoing eruption and quantifying the mass eruption rate in real time is a considerable challenge within the eu supersite project futurevolc an integrated approach has been applied to develop a quasi autonomous multi parameter system denoted refir for monitoring volcanic eruptions in iceland and assessing the eruption mass flow rate by inverting the plume height information and taking account of these uncertainties refir has the capability to ingest and process streaming plume height data provided by a multitude of ground based sensors including c and x band radars and web cam based plume height tracking systems these observational data are used with a suite of plume models that also consider the current wind and other atmospheric conditions providing statistically assessed best estimates of plume height and mass eruption rate provided instrumental data is available near real time estimates are obtained the delay corresponding to the scan rate of data providing instruments presently of the order of minutes using the hekla 2000 and eyjafjallajokull 2010 eruptions in iceland the potential of refir is demonstrated and discussed through application to three scenarios the system has been developed to provide maximum flexibility a setup script assists the user in adapting to local conditions allowing implementation of refir for any volcanic eruption site worldwide refir is designed to be easily upgradable allowing future extension of monitoring networks learning from new events and incorporation of new technologies and model improvements this article gives an overview of the basic structure models implemented functionalities and the computational techniques of refir

gps velocity field for the tien shan and surrounding regions 1 measurements at 400 campaign style gps points and another 14 continuously recording stations in central asia define variations in their velocities both along and across the kyrgyz and neighboring parts of tien shan they show that at the longitude of kyrgyzstan the tarim basin converges with eurasia at 20 2 mm yr nearly two thirds of the total convergence rate between india and eurasia at this longitude this high rate suggests that the tien shan has grown into a major mountain range only late in the evolution of the india eurasia collision most of the convergence between tarim and eurasia within the upper crust of the tien shan presumably occurs by slip on faults on the edges of and within the belt but 1 3 mm yr of convergence is absorbed farther north at the dzungarian alatau and at a lower rate with the kazakh platform to the west the tarim basin is thrust beneath the tien shan at 4 7 mm yr with respect to eurasia the ferghana valley rotates counterclockwise at 0 7 myr 1 about an axis at the southwest end of the valley thus gps data place a bound of 4 mm yr on the rate of crustal shortening across the chatkal and neighboring ranges on the northwest margin of the ferghana valley and they limit the present day slip rate on the right lateral talas ferghana fault to less than 2 mm yr gps measurements corroborate geologic evidence indicating that the northern margin of the pamir overthrusts the alay valley and require a rate of at least 10 and possibly 15 mm yr

factors influencing the height of hawaiian lava fountains implications for the use of fountain height as an indicator of magma gas content the heights of lava fountains formed in hawaiian style eruptions are controlled by magma gas content volume flux and the amounts of lava re entrainment and gas bubble coalescence theoretical models of lava fountaining are used to analyse data on lava fountain height variations collected during the 1983 1986 pu u o o vent of kilauea volcano hawaii the results show that the variable fountain heights can be largely explained by the impact of variations in volume flux and amount of lava re entrainment on erupting magmas with a constant gas content of 0 32 wt h2o however the gas content of the magma apparently declined by 0 05 wt during the last 10 episodes of the eruption series and this decline is attributed to more extensive pre eruption degassing due to a shallowing of the sub vent feeder dike it is concluded that variations in lava fountain height cannot be simply interpreted as variations in gas content as has previously been suggested but that fountain height can still be a useful guide to minimum gas contents where sufficient data are available on eruptive volume fluxes and extent of lava entrainment greatly improved estimates can be made of magma gas content from lava fountain height

high speed imaging of strombolian explosions the ejection velocity of pyroclasts explosive volcanic eruptions are defined as the violent ejection of gas and hot fragments from a vent in the earth s crust knowledge of ejection velocity is crucial for understanding and modeling relevant physical processes of an eruption and yet direct measurements are still a difficult task with largely variable results here we apply pioneering high speed imaging to measure the ejection velocity of pyroclasts from strombolian explosive eruptions with an unparalleled temporal resolution measured supersonic velocities up to 405 m s are twice higher than previously reported for such eruptions individual strombolian explosions include multiple sub second lasting ejection pulses characterized by an exponential decay of velocity when fitted with an empirical model from shock tube experiments literature this decay allows constraining the length of the pressurized gas pockets responsible for the ejection pulses these results directly impact eruption modeling and related hazard assessment as well as the interpretation of geophysical signals from monitoring networks

the 2011 tohoku tsunami on the coast of mexico a case study the tohoku east japan earthquake of 11 march 2011 m w 9 0 generated a great trans oceanic tsunami that spread throughout the pacific ocean where it was measured by numerous coastal tide gauges and open ocean dart deep ocean assessment and reporting of tsunamis stations statistical and spectral analyses of the tsunami waves recorded along the pacific coast of mexico have enabled us to estimate the principal parameters of the waves along the coast and to compare statistical features of the tsunami with other tsunamis recorded on this coast we identify coastal hot spots manzanillo zihuatanejo acapulco and ensenada corresponding to sites having highest tsunami hazard potential where wave heights during the 2011 event exceeded 1 5 2 m and tsunami induced currents were strong enough to close port operations based on a joint spectral analysis of the tsunamis and background noise we reconstructed the spectra of tsunami waves in the deep ocean and found that with the exception of the high frequency spectral band 5 cph the spectra are in close agreement with the true tsunami spectra determined from dart bottom pressure records the departure of the high frequency spectra in the coastal region from the deep sea spectra is shown to be related to background infragravity waves generated in the coastal zone the total energy and frequency content of the tohoku tsunami is compared with the corresponding results for the 2010 chilean tsunami our findings show that the integral open ocean tsunami energy i 0 was 2 30 cm2 or approximately 1 7 times larger than for the 2010 event comparison of this parameter with the mean coastal tsunami variance 451 cm2 indicates that tsunami waves propagating onshore from the open ocean amplified by 14 times the same was observed for the 2010 tsunami the tsunami colour frequency content for the 2011 tohoku tsunami was red with about 65 of the total energy associated with low frequency waves at frequencies 35 min the red colour i e the prevalence of low frequency waves in the 2011 tohoku as well as in the 2010 chile tsunamis is explained by the large extension of the source areas in contrast the 2014 and 2015 chilean earthquakes had much smaller source areas and consequently induced bluish high frequency tsunamis

crust and upper mantle structure beneath western china from p wave travel time tomography 1 three dimensional velocity images of the crust and upper mantle beneath western china are obtained through seismic tomography by using p wave arrival times of local regional and teleseismic events recorded in chinese and kyrgyzstan seismic networks at shallow depths most mountain belts and tectonically elevated areas are imaged as higher velocities relative to adjacent sediment filled basins and foreland depressions with lower velocities at mid lower crust depths the kyrgyz tian shan is underlain by lower velocity material and a distinct low velocity zone in the south north direction is observed between the eastern and western parts of the chinese tian shan the moho of the southern tarim basin has a greater depth over 50 km in front of the western kun lun compared to the northern and western tarim basin lateral heterogeneity within the upper mantle is apparent at depths from 71 to 571 km the uppermost mantle beneath the kyrgyz tian shan altay qi lian and eastern kun lun is characterized by low velocity material that is probably related to the upwelling of hot mantle the lithospheric thickness varies from 120 to 170 km beneath the chinese tian shan and northern tibetan plateau to 200 250 km beneath the tarim basin deep coupling pattern of the chinese tian shan with adjacent provinces can be classified into the embedding detaching and sinking and underthrusting of lithospheric roots in addition the lithosphere of the northern edge of the tibetan plateau seems to be thickened in contrast to the central part of the northern plateau north dipping low velocities exist in the upper mantle between the tibetan plateau and provinces to its north which might indicate mantle flow from the tibetan plateau toward surrounding areas but it has been blocked by the thick tarim lithosphere

the december 2018 anak krakatau volcano tsunami as inferred from post tsunami field surveys and spectral analysis we present analysis of the december 2018 anak krakatau tsunami in sunda strait indonesia from a combination of post tsunami field surveys bathymetric changes and spectral analysis of the tsunami tide gauge records post tsunami surveys revealed moderate tsunami height along the coast of sumatra and java with maximum surveyed runup of 13 5 m and maximum inundation distance of 330 m at small islands located close to the volcano extreme tsunami impacts were observed indicating not only a huge tsunami was generated by large amounts of collapse material which caused notable changes of seafloor bathymetry but also indicates the role of those small islands in reducing tsunami height that propagated to the mainland of indonesia our spectral analysis of tide gauge records showed that the tsunami s dominant period was 6 6 7 4 min indicating the short period nature of the 2018 sunda strait tsunami

physical parameterization of strombolian eruptions via experimentally validated modeling of high speed observations pressurized gas drives explosive volcanic eruptions existing models can predict the amount and pressure of gas in erupting magma but application and testing of such models is currently limited by the accuracy of input parameters from natural systems here we present a new methodology based on a novel integration of 1 high speed imaging and 2 shock tube modeling of volcanic activity in order to derive estimates of sub second variations in the pressure mass and volume of gas that drive the dynamics of unsteady eruptions first we validate the method against laboratoryscale shock tube experiments having validated the method we then apply it to observations of eruptions at stromboli volcano italy finally we use those results for a parametric study of the weight of input parameters on final outputs we conclude that strombolian explosions with durations of seconds result from discrete releases of gas with mass and pressure in the 4 714 kg and 0 10 0 56 mpa range respectively and which occupy the volcano conduit to a depth of 4 190 m these variations are present both among and within individual explosions

degassing at low magma viscosity volcanoes quantifying the transition between passive bubble burst and strombolian eruption abstract at many volcanoes low magma viscosities allow persistent degassing over a range of styles from explosive strombolian activity to gas puffing and passive degassing it is generally accepted that strombolian eruptions reflect the bursting of large bubbles gas slugs at the magma surface and that relatively quiescent puffing indicates the presence of significantly smaller bubbles or slugs here we address this qualitative range and derive a dimensionless parameter pslim to quantify and distinguish different regimes of burst vigour for pslim 1 passive activity is anticipated and measurable parameters such as infrasonic amplitude will be small for pslim 1 bursting slugs will be energetic and surface effects are anticipated to increase with increasing pslim various physical parameters recorded during laboratory experiments and simulated through numerical models are shown to demonstrate the same trends when parameterised by pslim hence pslim provides a straightforward relationship between changes in measurable surface effects and the system s subsurface physical parameters and for energetic activity of a particular system burst effects are shown to be proportional to the square root of the gas mass involved effect magnitudes are also shown to be a function of atmospheric pressure and application of pslim parameterisation to planetary scenarios produces results in line with our current understanding of planetary volcanism

the distribution of the mid to lower crustal low velocity zone beneath the northeastern tibetan plateau revealed from ambient noise tomography we collected continuous seismic data recorded between 2007 and 2010 by 208 broadband stations from the chinese provincial digital seismic networks a seismic collaborative experiment of northern tibet and the northeastern tibet seismic experiment cross correlations of vertical component records are computed to extract the rayleigh wave empirical green s functions group and phase velocities are then constructed from the empirical green s functions in 8 to 50 s period at periods 25 s more than 10 lower velocities are imaged beneath the qaidam basin and high velocities are observed beneath the nonbasin regions at periods 30 s up to 10 lower velocities are imaged in the qiangtang and songpan ganze terranes from these group and phase velocity maps a three dimensional 3 d vsv model of the crust is derived the model shows that the qiangtang and songpan ganze terranes have a very thick crust with a prominent low velocity zone lvz in the middle crust the lvz thins out in the vicinity of the eastern kunlun mountains providing a new constraint on the mode of deformation across the tibetan plateau the northwestern qilian orogen where receiver functions reveal a moho deeper than the surrounding areas also features a relatively weak midcrustal lvz which we interpret as an intracrustal response associated with the shortening between the north china craton and the tibetan plateau

video monitoring reveals pulsating vents and propagation path of fissure eruption during the march 2011 pu u ō ō eruption kilauea volcano abstract lava fountains are a common eruptive feature of basaltic volcanoes many lava fountains result from fissure eruptions and are associated with the alignment of active vents and rising gas bubbles in the conduit visual reports suggest that lava fountain pulses may occur in chorus at adjacent vents the mechanisms behind such a chorus of lava fountains and the underlying processes are however not fully understood the march 2011 eruption at pu u kilauea volcano was an exceptional fissure eruption that was well monitored and could be closely approached by field geologists the fissure eruption occurred along groups of individual vents aligned above the feeding dyke we investigate video data acquired during the early stages of the eruption to measure the height width and velocity of the ejecta leaving eight vents using a sobel edge detection algorithm the activity level of the lava fountains at the vents was determined revealing a similarity in the eruption height and frequency based on this lava fountain time series we estimate the direction and degree of correlation between the different vents we find that the height and velocity of the eruptions display a small but systematic shift in time along the vents indicating a lateral migration of lava fountaining at a rate of 11 m s from w to e this finding is in agreement with a propagation model of a pressure wave originating at the kilauea volcano and propagating through the dyke at 10 m s from w to e based on this approach from videos only 30 s long we are able to obtain indirect constraints on the physical dyke parameters with important implications for lateral magma flow processes at depth this work shows that the recording and analysis of video data provide important constraints on the mechanisms of lava fountain pulses even though the video sequence is short it allows for the confirmation of the magma propagation direction and a first order estimation of the dyke dimensions

tectonics and topography for a lithosphere containing density heterogeneities the purpose of this paper is to clarify the dynamic role of lithospheric density heterogeneities in particular with respect to mountain building and other processes of intraplate deformation density anomalies within or just beneath the lithosphere constitute major sources for tectonic stress fields the product of their magnitude by their depth is shown to characterize their ability to induce deformation this rule of the density moment directly yields the lithospheric thickening or thinning rate when applied to structures of large lateral extent for anomalies of lateral extent that is small in comparison with their depth the deformation is vertically inhomogeneous and has been computed with the help of simple physical models of a stratified viscous newtonian lithosphere the analytical treatment is based on fourier transform continent continent collision thickens not only the crust but the entire lithosphere the cold root underlying a mountain chain induces strong regional compressive stresses able to sustain the mountain bulding process without further help from forces transmitted from far away thus the continental lithosphere is in a somewhat metastable mechanical state adiabatic i e rapid thickening or thinning tends to grow further once initiated tectonic phases of strong compression correspond to the climax of such instabilities the response of models with cold lithospheric roots of various intensities has been computed both in two and three dimensions they yield velocity distributions and stress fields instructive comparisons are made with earthquake focal mechanisms and in situ stress measurements in the alpine and appalachian regions in the presence of lateral variations of the mechanical properties of the lithosphere the tectonic style is not only function of the local topography and of the nature of its compensation deformations in neighbouring provinces are coupled as shown by 3 dimensional models for example thickening sustained by a cold lithospheric root may generate extension in peripheral zones of weakness these last results illustrate the point that the computation of regional tectonic stresses requires the knowledge of the density anomalies within the lithosphere on the one hand and of geometrical constraints related to lateral mechanical heterogeneities on the other

oblique photogrammetry with visible and thermal images of active lava flows digital images from hand held cameras are increasingly being acquired for scientific purposes particularly where non contact measurement is required however they frequently consist of oblique views with significant camera to object depth variations and occlusions that complicate quantitative analyses here we report the use of oblique photogrammetric techniques to determine ground based thermal camera orientations position and pointing direction and to generate scene information for lava flows at mount etna sicily multiple images from a consumer grade digital slr camera are used to construct a topographic model and reference associated ground based thermal imagery we present data collected during the 2004 2005 eruption and use the derived surface model to apply viewing distance corrections to account for atmospheric attenuation to the thermal images on a pixel by pixel basis for viewing distances of 100 to 400 m the corrections result in systematic changes in emissive power of up to 3 with respect to values calculated assuming a uniform average viewing distance across an image

tide gauge observations of the indian ocean tsunami december 26 2004 the magnitude 9 0 earthquake centered off the west coast of northern sumatra 3 307 n 95 947 e on december 26 2004 at 00 59 utc united states geological survey usgs 2005 usgs earthquake hazards program latest earthquakes earthquake hazards program http earthquake usgs gov eqinthenews 2004 usslav 2005 generated a series of tsunami waves that devastated coastal areas throughout the indian ocean tide gauges operated on behalf of national and international organizations recorded the wave form at a number of island and continental locations this report summarizes the tide gauge observations of the tsunami in the indian ocean available as of january 2005 and provides a recommendation for the use of the basin wide tide gauge network for future warnings

geodynamics of the tarim basin and the tian shan in central asia the india asia collision has caused crustal thickening in tibet by at least a factor of 2 in the last 20 30 myr of this collision the tian shan mountain range has also been reactivated the tarim basin however shows little internal deformation we describe a series of numerical experiments which constrain the effective lithospheric strength parameters of the tarim basin and the tian shan in the context of a thin viscous sheet model we use a finite element representation of the thin viscous sheet model to approximate the deformation field in the india asia collision and compare model crustal thickness distributions with that inferred from a local isostatic model of topography the experiments show that a strong tarim basin while undergoing little internal deformation transfers strain to the tian shan producing significant crustal thickening in the tian shan region based only on diagnostic parameters such as the maximum thickening in the tian shan and the minimum in the tarim basin the principal features of the topography can be approximately reproduced using models in which either the tarim basin is strong or the tian shan is weak or both for a rheological model in which the stress versus strain rate exponent is n 3 the strength coefficient for the strong tarim basin model vtarim is between about 1 7 and 2 for the weak tian shan model the relative strength coefficient vtian is between about 0 65 and 0 75 if both strong tarim and weak tian shan are included there is a trade off between the required values of vtarim and vtian and the shape of the predicted crustal thickness profiles better matches the observed profiles the steep topographic slope on the southern margin of the tarim basin requires that it is anomalously strong while the rapid decrease of topographic height to the north of the tian shan requires that it is anomalously weak similar conclusions are obtained with a rheological model based on n 10 simplified rheological models of the lithosphere show that the variations in lithospheric strength may be explained by changes to the moho temperature of the order of 10 to 30 c

tectonic history of the kyrgyz south tien shan atbashi inylchek suture zone the role of inherited structures during deformation propagation 1 multimethod chronology was applied on intrusives bordering the kyrgyz south tien shan suture stss to decipher the timing of 1 formation and amalgamation of the suturing units and 2 intracontinental deformation that built the bordering mountain ranges zircon u pb data indicate similarities between the tien shan and tarim precambrian crust caledonian 440 410 ma and hercynian 310 280 ma zircon u pb ages were found at the edge of the stss related to subduction and closure of the turkestan ocean and the formation of the suture itself permian triassic 280 210 ma titanite fission track and zircon u th he data record the first signs of exhumation when the stss evolved into a shear zone and the adjacent tarim basin started to subside low temperature thermochronological apatite fission track zircon and apatite u th he analyses reveal three distinct cooling phases becoming younger toward the stss center 1 jurassic cretaceous cooling ages provide evidence that a mesozoic south tien shan orogen formed as a response to the cimmerian orogeny 2 early paleogene 60 45 ma data indicate a renewed pulse of stss reactivation during the early cenozoic 3 neogene ages constrain the onset of the modern tien shan mountain building to the late oligocene 30 25 ma which intensified during the miocene 10 8 ma and pliocene 3 2 ma the cenozoic signals may reflect renewed responses to collisions at the southern eurasian border i e the kohistan dras and india eurasia collisions this progressive rejuvenation of the stss demonstrates that deformation has not migrated steadily into the forelands but was focused on pre existing basement structures

monitoring lava dome growth during the 2004 2008 mount st helens washington eruption using oblique terrestrial photography abstract we present an analysis of lava dome growth during the 2004 2008 eruption of mount st helens using oblique terrestrial images from a network of remotely placed cameras this underutilized monitoring tool augmented more traditional monitoring techniques and was used to provide a robust assessment of the nature pace and state of the eruption and to quantify the kinematics of dome growth eruption monitoring using terrestrial photography began with a single camera deployed at the mouth of the volcano s crater during the first year of activity analysis of those images indicates that the average lineal extrusion rate decayed approximately logarithmically from about 8 m d to about 2 m d 2 m d from november 2004 through december 2005 and suggests that the extrusion rate fluctuated on time scales of days to weeks from may 2006 through september 2007 imagery from multiple cameras deployed around the volcano allowed determination of 3 dimensional motion across the dome complex analysis of the multi camera imagery shows spatially differential but remarkably steady to gradually slowing motion from about 1 2 m d from may through october 2006 to about 0 2 1 0 m d from may through september 2007 in contrast to the fluctuations in lineal extrusion rate documented during the first year of eruption dome motion from may 2006 through september 2007 was monotonic 0 10 m d to gradually slowing on time scales of weeks to months the ability to measure spatial and temporal rates of motion of the effusing lava dome from oblique terrestrial photographs provided a significant and sometimes the sole means of identifying and quantifying dome growth during the eruption and it demonstrates the utility of using frequent long term terrestrial photography to monitor and study volcanic eruptions

constraints on dike propagation from continuous gps measurements the january 1997 east rift zone eruption on kilauea volcano hawaii occurred within a network of continuous global positioning system gps receivers the gps measurements reveal the temporal history of deformation during dike intrusion beginning 8 hours prior to the onset of the eruption the dike volume as a function of time estimated from the gps data using elastic green s functions for a homogeneous half space shows that only two thirds of the final dike volume accumulated prior to the eruption and the rate of volume change decreased with time these observations are inconsistent with simple models of dike propagation which predict accelerating dike volume up to the time of the eruption and little or no change thereafter deflationary tilt changes at kilauea summit mirror the inferred dike volume history suggesting that the rate of dike propagation is limited by flow of magma into the dike a simple lumped parameter model of a coupled dike magma chamber system shows that the tendency for a dike to end in an eruption rather than intrusion is favored by high initial dike pressures compressional stress states large compressible magma reservoirs and highly conductive conduits linking the dike and source reservoirs comparison of model predictions to the observed dike volume history the ratio of erupted to intruded magma and the deflationary history of the summit magma chamber suggest that most of the magma supplied to the growing dike came from sources near to the eruption through highly conductive conduits interpretation is complicated by the presence of multiple source reservoirs magma vesiculation and cooling as well as spatial variations in dike normal stress reinflation of the summit magma chamber following the eruption was measured by gps and accompanied a rise in the level of the pu u o o lava lake for a spheroidal chamber these data imply a summit magma chamber volume of 20 km3 consistent with recent estimates from seismic tomography continuous deformation measurements can be used to image the spatiotemporal evolution of propagating dikes and to reveal quantitative information about the volcanic plumbing systems

explosive volcanic eruptions ix the transition between hawaiian style lava fountaining and strombolian explosive activity the commonest eruption styles of basaltic volcanoes involve hawaiian lava fountaining or intermittent strombolian explosions we investigate the ways in which magma rise speed at depth magma volatile content and magma viscosity control which of these eruption styles takes place we develop a model of the degree of coalescence between gas bubbles in the magma which allows us to simulate the transition between the two extreme styles of activity we find that magma rise speed is the most important factor causing the transition with gas content and viscosity also influencing the rise speed at which the transition occurs counter to intuitive expectations a decrease in gas content does not cause a transition from hawaiian to strombolian activity but instead causes a transition to passive effusion of vesicular lava rather a change from hawaiian to strombolian style requires a significant reduction in magma rise speed

photogrammetric monitoring of lava dome growth during the 2009 eruption of redoubt volcano abstract the 2009 eruption of redoubt volcano alaska began with a phreatic explosion on 15 march followed by a series of at least 19 explosive events and growth and destruction of at least two and likely three lava domes between 22 march and 4 april on 4 april explosive activity gave way to continuous lava effusion within the summit crater we present an analysis of post 4 april lava dome growth using an oblique photogrammetry approach that provides a safe rapid and accurate means of measuring dome growth photogrammetric analyses of oblique digital images acquired during helicopter observation flights and fixed wing volcanic gas surveys produced a series of digital elevation models dems of the lava dome from 16 april to 23 september the dems were used to calculate estimates of volume and time averaged extrusion rates and to quantify morphological changes during dome growth effusion rates ranged from a maximum of 35 m 3 s 1 during the initial two weeks to a low of 2 2 m 3 s 1 in early summer 2009 the average effusion rate from april to july was 9 5 m 3 s 1 early rapid dome growth was characterized by extrusion of blocky lava that spread laterally within the summit crater in mid to late april the volume of the dome had reached 36 10 6 m 3 roughly half of the total volume and dome growth within the summit crater began to be limited by confining crater walls to the south east and west once the dome reached the steep north sloping gorge that breaches the crater growth decreased to the south but the dome continued to inflate and extend northward down the gorge effusion slowed during 16 april 1 may but in early may the rate increased again this rate increase was accompanied by a transition to exogenous dome growth from mid may to july the effusion rate consistently declined the decrease is consistent with observations of reduced seismicity gas emission and thermal anomalies as well as declining rates of geodetic deflation or inflation these trends suggest dome growth ceased by july 2009 the volume of the dome at the end of the 2009 eruption was about 72 10 6 m 3 more than twice the estimated volume of the largest dome extruded during the 1989 1990 eruption in total the 2009 dome extends over 400 m down the glacial gorge on the north end of the crater with a total length of 1 km width of 500 m and an average thickness of 200 m

deep sea observations and modeling of the 2004 sumatra tsunami in drake passage 1 the 2004 sumatra tsunami was clearly recorded by two uk bottom pressure gauges dpn and dps deployed in drake passage between south america and antarctica these open ocean records were examined to estimate characteristics of the tsunami waves and to compare the results of numerical simulations with the observations maximum wave heights measured at these gauges were 4 9 cm at dpn and 7 4 cm at dps the travel times from the source area were 19 h 46 min and 19 h 39 min respectively consistent with the times obtained from the nearby coastal tide gauges the numerical model described well the frequency content amplitudes and general structure of the observed waves with only small time shifts probably related to wave dispersion effects the shifts were 15 min for dpn and 10 min for dps with the modeled waves leading the observations in each case further inspection of the simulated and observed records revealed that the identified tsunami waves are related to the second main train of waves propagating by the energy conserving route along the mid ocean ridges while the first train of waves travelling by the fastest route across the ocean remained unrecognizable in the observed dps and dpn records and undetectable in the records of coastal tide gauges because of their insignificant amplitudes compared to the background variability

a comparative analysis of coastal and open ocean records of the great chilean tsunamis of 2010 2014 and 2015 off the coast of mexico the three great earthquakes off the coast of chile on 27 february 2010 maule mw 8 8 1 april 2014 iquique mw 8 2 and 16 september 2015 illapel mw 8 3 generated major transoceanic tsunamis that spread throughout the pacific ocean and were measured by numerous coastal tide gauges and open ocean dart stations statistical and spectral analyses of the tsunami waves from the events recorded on the pacific coast of mexico enabled us to estimate parameters of the waves along the coast and to compare statistical features of the events we also identified three coastal hot spots sites having maximum tsunami risk puerto angel puerto madero and manzanillo based on the joint spectral analyses of the tsunamis and background noise we have developed a method for using coastal observations to determine the underlying spectrum of tsunami waves in the deep ocean the reconstructed open ocean tsunami spectra are in close agreement with the actual tsunami spectra evaluated from direct analysis of the dart records offshore of mexico we have further used the spectral estimates to parameterize the energy of the three chilean tsunamis based on the total open ocean tsunami energy and frequency content of the individual events

fumarole monitoring with a handheld infrared camera volcan de colima mexico 2006 2007 abstract this paper describes a methodology for the monitoring of fumarole temperatures at medium ranges 6 km using a handheld infrared camera wavelength range 8 13 5 m as a relationship between fumarole temperatures gas flux and volcanic activity has been demonstrated by a number of studies fumarole temperature data has a potential use as a monitoring tool volcan de colima is an andesitic stratovolcano with a 300 m diameter summit crater formed by the destruction of the 2004 lava dome by a series of explosions in 2005 between january 2006 and august 2007 sequences of thermal images were recorded from a viewpoint 6 km to the north during regular 24 48 hour monitoring excursions the temperatures of fumaroles on the crater rim and the ground surface on the volcano s flanks were measured a methodology was developed to remove data affected by clouds or volcanic water vapour based on rates of temperature change and scatter within the data for the remaining data it is demonstrated mathematically that at this range typical variations in atmospheric transmissivity will affect the apparent temperatures by 2 c while a 25 change in fumarole heat flux would change it by 5 10 c the mean night time apparent temperature of the fumaroles was calculated for each excursion and showed an irregular decline over the 19 month period subtracting the radiant heat flux of flank rocks from those of the fumaroles removes seasonal variations and gives the clearest view of trends in the fumarole heat flux a sharp drop in fumarole temperature during february 2007 coincided with the emergence of a lava dome in the crater the declining fumarole temperature is interpreted to reflect decreasing gas flux from the crater in line with a change in eruptive regime from frequent small ash rich explosions to slow effusion of lava

new insight into crustal and lithospheric variability beneath the central tien shan nw china revealed by p wave receiver functions abstract the tien shan has experienced intensive crustal shortening and lithospheric deformation making it an ideal site to study the orogeny processes we applied p wave receiver functions to get new insight into crustal and lithospheric variability beneath the central shan region clear p to s converted phases are observed at many recording stations exhibiting double positive converted phases at 5 9 s the corresponding crustal thickness varies from 35 km to 70 km which appears to be relatively thinner beneath the kazakh shield and tarim basin and thicker beneath the southern and northern flanks of the central tien shan the negative converted phases are observed at depths of 30 45 km beneath the central tien shan corresponding to the extremely low seismic velocities in the middle to lower crust revealed by seismic tomography the receiver function results coupled with a regional shear wave velocity model suggest that the lithosphere of the central tien shan has been significantly modified the thickening and thinning of lithosphere may be related to up warped and down warped of mantle and could be associated with the mantle upwelling triggered by bilateral underthrusting of the tarim basin and the kazakh shield respectively beneath the central tien shan

dynamics of degassing at kilauea volcano hawaii at kilauea volcano hawaii the recent long lived eruptions of mauna ulu and pu u o o have occurred in two major stages defining a characteristic eruptive pattern the first stage consists of cyclic changes of activity between episodes of fire fountaining and periods of quiescence or effusion of vesicular lava the second stage consists only of continuous effusion of lava we suggest that these features reflect the dynamics of magma degassing in a chamber which empties into a narrow conduit in the volcano chamber gas bubbles rise through magma and accumulate at the roof in a foam layer the foam flows toward the conduit and its shape is determined by a dynamic balance between the input of bubbles from below and the output into the conduit the foam thickness is proportional to lq e2 l g 1 4 where l and l are the viscosity and density of magma e is the gas volume fraction in the foam g is the acceleration of gravity and q is the gas flux the bubbles in the foam deform under the action of buoyancy and the maximum permissible foam thickness is hc 2 e lgr where is the coefficient of surface tension and r is the original bubble radius if this critical thickness is reached the foam collapses into a large gas pocket which erupts into the conduit foam accumulation then resumes and a new cycle begins the attainment of the foam collapse threshold requires a gas flux in excess of a critical value which depends on viscosity surface tension and bubble size hence two different eruption regimes are predicted 1 alternating regimes of foam buildup and collapse leading to the periodic eruption of large gas volumes and 2 steady foam flow at the roof leading to continuous bubbly flow in the conduit the essential result is that the continuous process of degassing can lead to discontinuous eruptive behavior data on eruption rates and repose times between fountaining phases from the 1969 mauna uiu and the 1983 1986 pu u o o eruptions yield constraints on three key variables the area of the chamber roof must be a few tens of square kilometers with a minimum value of about 8 km2 magma reservoirs of similar dimensions are imaged by seismic attenuation tomography below the east rift zone close to the roof the gas volume fraction is a few percent and the gas bubbles have diameters lying between 0 1 and 0 6 mm these estimates are close to the predictions of models for bubble nucleation and growth in basaltic melts as well as to the observations on deep submarine basalts the transition between cyclic and continuous activity occurs when the mass flux of gas becomes lower than a critical value of the order of 103 kg s in this model changes of eruptive regime reflect changes in the amount and size of bubbles which reach the chamber roof

traveltime delay and initial phase reversal of distant tsunamis coupled with the self gravitating elastic earth systematic tsunami traveltime delays of up to 15 min relative to the numerically simulated long waves from the 2010 chilean and 2011 tohoku oki earthquakes were widely observed at deep ocean tsunamimeters enigmatic small negative phases appearing before the main peak were commonly found only at the trans oceanic locations the frequency dependence of the measured tsunami phase velocities shows reverse dispersions at long periods i e the tsunami speed becomes slower at periods beyond 1000 s this is consistent with the phase velocities of a tsunami mode coupled with a self gravitating elastic earth suggesting that the effects of compression and dilatation of seawater elastic tsunami loadings on a solid earth and the geopotential variations associated with the motion of mass during tsunami propagation are responsible for the traveltime delays and the initial negative phases simple 1 d tsunami propagation tests confirm that the reverse dispersion creates a small negative phase that precedes the main peak at large distances a new method to simulate tsunami waveforms on real ocean bathymetry that takes into account seawater compressibility the elasticity of the earth and geopotential perturbations has been developed by applying a phase correction to the simulated long waves the simulated waveforms in which phase corrections are applied for the dispersion effects accurately reproduce the observed waveforms including a small initial negative phase that appears at distant locations the traveltime difference between the observed and simulated waveforms has been decreased to less than 5 min and the waveform difference between them remarkably diminishes

real time experimental forecast of the peruvian tsunami of august 2007 for u s coastlines 1 at 23 41 utc on 15 august 2007 an offshore earthquake of magnitude 8 0 severely damaged central peru and generated a tsunami severe shaking by the earthquake collapsed buildings throughout the region and caused 514 fatalities the tsunami resulted in three casualties and a representative maximum runup height of 7 m in the near field the first real time tsunami data available came from a deep ocean tsunami detection buoy within 1 hour of tsunami generation these tsunami data were used to produce initial experimental forecasts within 2 hours of tsunami generation the far field forecasts indicated that the tsunami would not flood any of the 14 u s communities comparison with real time tide gage data showed very accurate forecasts

the 21 may 2003 tsunami in the western mediterranean sea statistical and wavelet analyses we report the statistical and wavelet analyses of the 21 may 2003 tsunami produced by an mw 6 8 6 9 thrust earthquake in the western mediterranean sea using 19 tide gauge records the largest trough to crest wave height was 196 cm recorded at the sant antoni station in the lee of the incoming tsunami wave except at one station the first wave was not the largest wave at all the analyzed stations and the largest wave arrived several hours after the first arrival in addition the tsunami waves persisted for more than 1 day at most stations as the spectra of coastal tide gauge stations are strongly influenced by topographic features special care was taken here while interpreting the results of spectral and wavelet analysis our wavelet analysis shows that only a peak at around 23 min is persistent for long duration and other peaks at 14 30 45 and 60 min appeared at short durations the 23 min signal is possibly associated with the width of the source fault whereas the fault length contributed to the 45 min signal based on these dominant periods the tsunami source dimensions are estimated as 95 km 45 km the statistical and wavelet analyses performed here provide some new insights into the characteristics of the tsunami that was generated and propagated in the western mediterranean basin

the 26 december 2004 sumatra tsunami analysis of tide gauge data from the world ocean part 1 indian ocean and south africa the m w 9 3 megathrust earthquake of december 26 2004 off the northwest coast of sumatra in the indian ocean generated a catastrophic tsunami that was recorded by a large number of tide gauges throughout the world ocean part 1 of our study of this event examines tide gauge measurements from the indian ocean region at sites located from a few hundred to several thousand kilometers from the source area statistical characteristics of the tsunami waves including wave height duration and arrival time are determined along with spectral properties of the tsunami records

the global reach of the 26 december 2004 sumatra tsunami numerical model simulations combined with tide gauge and satellite altimetry data reveal that wave amplitudes directionality and global propagation patterns of the 26 december 2004 sumatra tsunami were primarily determined by the orientation and intensity of the offshore seismic line source and subsequently by the trapping effect of mid ocean ridge topographic waveguides

improved phase corrections for transoceanic tsunami data in spatial and temporal source estimation application to the 2011 tohoku earthquake systemic travel time delays of up to 15 min relative to the linear long waves for transoceanic tsunamis have been reported a phase correction method which converts the linear long waves into dispersive waves was previously proposed to consider seawater compressibility the elasticity of the earth and gravitational potential change associated with tsunami motion in the present study we improved this method by incorporating the effects of ocean density stratification actual tsunami raypath and actual bathymetry the previously considered effects amounted to approximately 74 for correction of the travel time delay while the ocean density stratification actual raypath and actual bathymetry contributed to approximately 13 4 and 9 on average respectively the improved phase correction method accounted for almost all the travel time delay at far field stations we performed single and multiple time window inversions for the 2011 tohoku tsunami using the far field data 3 h travel time to investigate the initial sea surface displacement the inversion result from only far field data was similar to but smoother than that from near field data and all stations including a large sea surface rise increasing toward the trench followed by a migration northward along the trench for the forward simulation our results showed good agreement between the observed and computed waveforms at both near field and far field tsunami gauges as well as with satellite altimeter data the present study demonstrates that the improved method provides a more accurate estimate for the waveform inversion and forward prediction of far field data

direct energy estimation of the 2011 japan tsunami using deep ocean pressure measurements 1 we have developed a method to compute the total energy transmitted by tsunami waves to the case where the earthquake source is unknown by using deep ocean pressure measurements and numerical models tsunami source functions based on the first wave recorded at the two closest tsunameters deep ocean assessment and reporting of tsunamis dart our analysis suggests that the march 11 2011 tohoku oki tsunami generated off japan originated from a 300 400 km long and 100 km wide area and the total propagated energy is 3 1015j with 6 uncertainty measurements from 30 tsunameters and 32 coastal tide stations show excellent agreement with the forecasts obtained in real time our study indicates that the propagated energy and the source location are the most important source characteristics for predicting tsunami impacts interactions of tsunami waves with seafloor topography delay and redirect the energy flux posing hazards from delayed and amplified waves with long duration seafloor topography also gives its spectral imprint to tsunami waves travel time forecast errors are path specific and correlated to the major wave scatterers in the pacific numerical dissipation in the propagation modeling highlights the need of high resolution inundation models for accurate coastal predictions on the other hand it also can be used to account for physical dissipation to achieve efficiency our results provide guidelines for the earliest reliable tsunami forecast warnings of long duration tsunami waves signals and enhancement of the experimental tsunami forecast system we apply the method to quantify the energy of 15 past tsunamis independently from earthquake magnitudes the small tsunami to seismic radiation energy ratios and their variability 0 01 0 8 reinforce the importance of using deep ocean tsunami data the direct measures of tsunamis for estimates of tsunami energy and accurate forecasting

image based measurement of flux variation in distal regions of active lava flows 1 understanding the processes involved with the advance of lava flows is critical for improving hazard assessments at many volcanoes here we describe the application of computer vision and oblique photogrammetric techniques to visible and thermal images of active a flows in order to investigate distal flow processes at mount etna sicily photogrammetric surveys were carried out to produce repeated topographic data sets for calculation of volumetric lava flux at the flow fronts velocity profiles from a distal channel were obtained by rectification of a thermal image sequence and are used to investigate the rheological properties of the lava significant variations of the magma flux were observed and pulses of increased flux arrived within the flow front region on timescales of several hours the pulses are believed to be the distal result of more frequent flux changes observed in the vent region hence they reflect the importance of flow processes which are believed to cause the coalescence of flux pulses along the channel system as well as short period variations in effusion rate in considering advance processes for the individual flow fronts it must be assumed that they were fed by a highly unsteady flux which was volumetrically at least an order of magnitude lower than that observed near the vent

coupled textural and compositional characterization of basaltic scoria insights into the transition from strombolian to fire fountain activity at mount etna italy strombolian and fire fountain activities represent a common expression of explosive basaltic eruptions however the transition between these two eruptive styles and their source mechanisms are still debated we use textural and compositional studies to characterize pyroclastic material from both the strombolian and hawaiian style fire fountain phases of the january june 2000 etna activity we find that basaltic scoria presents distinctive textural and compositional features that reflect different modes of magma vesiculation and crystallization in the two eruptive regimes overall magma that forms strombolian scoria is far more crystallized less vesicular and more evolved indicating strong volatile depletion and longer residence time before being erupted fire fountain scoria indicates a fast rising magma with evidence of moderate syneruptive volatile exsolution the new textural and compositional data set is integrated with previous volcanological and geophysical investigations to provide further insights into the dynamics of fire fountains and to frame the transition from strombolian explosions to fire fountain activity into a model that may apply to future eruptions at mount etna as well as other active basaltic volcanoes

late quaternary slip rates across the central tien shan kyrgyzstan central asia 1 slip rates across active faults and folds show that late quaternary faulting is distributed across the central tien shan not concentrated at its margins nearly every intermontane basin contains neogene and quaternary syntectonic strata deformed by holocene north south shortening on thrust or reverse faults in a region that spans two thirds of the north south width of the central tien shan slip rates on eight faults in five basins range from 0 1 to 3 mm yr fault slip rates are derived from faulted and folded river terraces and from trenches radiocarbon optically stimulated luminescence and thermoluminescence ages limit ages of terraces and aid in their regional correlation monte carlo simulations that sample from normally distributed and discrete probability distributions for each variable in the slip rate calculations generate most likely slip rate values and 95 confidence limits faults in basins appear to merge at relatively shallow depths with crustal scale ramps that underlie mountain ranges composed of pre cenozoic rocks the sum and overall pattern of late quaternary rates of shortening are similar to current rates of north south shortening measured using global positioning system geodesy this similarity suggests that deformation is concentrated along major fault zones near range basin margins such faults separated by rigid blocks accommodate most of the shortening in the upper crust index terms 8107 tectonophysics continental neotectonics 9320 information related to geographic region asia 8010 structural geology fractures and faults

darts and cork in cascadia basin high resolution observations of the 2004 sumatra tsunami in the northeast pacific 1 we report unique deep sea recordings of the sumatra tsunami of december 2004 by high resolution dart deep ocean assessment and reporting of tsunami and cork circulation obviation retrofit kit bottom pressure sensors deployed at depths of 1500 3500 m in cascadia basin in the northeast pacific the simultaneous records from these sites establish the first ever regional scale tsunami detection array for the open ocean enabling us to resolve both seafloor and crustal tsunami signals and to determine fundamental properties of the waves following their 22 000 km journey from the source region waves reaching the basin had mean amplitudes of 5 mm with energy spread over a broad frequency band from 0 4 to 7 cph peak tsunami energy was in the 0 8 to 2 cph 75 to 30 min band leading waves from the event arrived 34 35 h after the earthquake roughly 7 h later than expected suggesting that the tsunami mainly propagated by the most economic minimum energy loss path along mid ocean ridge wave guides rather than taking the direct and fastest path across the ocean motions within the peak energy band comprise roughly 50 coherent progressive waves propagating from the south at longwave phase speeds of 150 ms 1 and 50 random waves scattered from the coast and bottom irregularities tsunami amplitudes in the borehole were one third those on the seafloor the extensive ringing and anomalously slow 3 5 day e folding decay time of the tsunami wave energy indicates long duration energy flux radiating from the indian ocean via the southern pacific ocean

spectral analysis of tsunami waves separation of source and topography effects a new approach is proposed to separate the influence of source and topography in observed tsunami spectra and to reconstruct the initial source spectrum the method assumes a linear tide gauge response to external forcing and is based on comparative analysis of tsunami and background spectra evaluation of the ratio of tsunami to background spectra gives functional characteristics that are invariant of station location and dependent only on the source parameters three events the urup tsunami of december 22 1991 northwest pacific the hokkaido southwest okushiri tsunami of july 12 1993 sea of japan and the shikotan tsunami of october 4 1994 northwest pacific are used as examples of the proposed approach the source spectra reconstructed from the analysis of different tide gauges were found to be in good agreement with each other and with the seismological geodetic and field survey data

multiple coincident eruptive seismic tremor sources during the 2014 2015 eruption at holuhraun iceland we analyze eruptive tremor during one of the largest effusive eruptions in historical times in iceland 2014 15 holuhraun eruption seismic array recordings are compared with effusion rates deduced from moderate resolution imaging spectroradiometer modis recordings and ground video monitoring data and lead to the identification of three coexisting eruptive tremor sources this contrasts other tremor studies that generally link eruptive tremor to only one source usually associated with the vent the three sources are i a source that is stable in back azimuth and shows bursts with ramp like decrease in amplitude at the beginning of the eruption we link it to a process below the open vents where the bursts correlate with the opening of new vents and temporary increases in the lava fountaining height ii a source moving by a few degrees per month while the tremor amplitude suddenly increases and decreases back azimuth and slowness correlate with the growing margins of the lava flow field whilst contact with a river led to fast increases of the tremor amplitude iii a source moving by up to 25 southwards in 4 days that cannot be related to any observed surface activity and might be linked to intrusions we therefore suggest that eruptive tremor amplitudes energies are used with caution when estimating eruptive volumes effusion rates or the eruption explosivity as multiple sources can coexist during the eruption phase our results suggest that arrays can monitor both the growth of a lava flow field and the activity in the vents

the mechanism of volcanic eruptions a steady state approach a theory of a volcanic eruption as a steady magma flow from a magma chamber to the surface is described magma is considered as a two component two phase medium and magma flow is steady one dimensional and isothermal mass and momentum exchange between condensed and gaseous phases is assumed to be in equilibrium with nucleation of bubbles as a fast process at small oversaturations three basic flow structures in a conduit are recognized and three resulting types of eruption are described 1 in the discrete gas separation dgs flow melt with discrete gas bubbles erupts this type includes lava eruptions and strombolian activity 2 in the dispersion regime there is continuous eruption of a gas pyroclastic suspension catastrophic explosive eruptions are included in this type 3 here a partly destroyed foam is erupted with permeable structure that allows gas escape near the surface this structure evolves with an increase in permeability and a decrease in the total porosity this type corresponds to lava dome extrusions a criterion dividing dgs flow from the other two regimes is obtained di u n1 3a c0 where u is the magma ascent velocity is magma viscosity n is number of bubble nuclei in a unit mass of magma a is the solubility coefficient for volatiles in magma and c0 is the volatile content the boundary between the dispersion regime and the partly destroyed foam regime depends on u c0 and particle size dp for the dispersion regime the basic governing parameters are magma chamber depth h conduit conductivity b2 b is the characteristic cross dimension of the conduit and excess pressure in the magma chamber instability of the dispersion regime is investigated numerically the dependence of magma discharge rate on the governing parameters is described as a combination of equilibrium surfaces with cusp catastrophes magma chamber depth is a splitting parameter in most cusps and controls the existence of unstable magma flow with sharp regime changes catastrophic rise of eruption intensity is possible if h hcr the critical chamber depth hcr depends approximately linearly on c0 and is about 15 km at c0 0 05 some scenarios of eruption evolution are described in a steady state approximation and the mechanism of catastrophic explosive eruptions is proposed the theory is applied to well documented eruptions tolbachik 1975 1976 and mount st helens 1980 the theory can also describe changes in a volcanic system such as destruction of the conduit or chamber walls destruction of the edifice changes in magma composition and caldera subsidence due to magma evacuation

explosive volcanic eruptions vii the ranges of pyroclasts ejected in transient volcanic explosions an earlier treatment of the motions of pyroclasts produced in discrete volcanic explosions assumed that clasts were ejected into a stationary atmosphere we argue here that the air in the vicinity of an explosion site will itself be moving radially away from the source with a speed comparable to that of the clasts especially at early times after the start of the motion as a result the initial relative velocity of clasts and air will be small in the earlier treatment this relative velocity was inevitably large leading to an overestimate of the atmospheric drag force at early times and a consequent underestimate of the final clast range we set up a simple model of the explosion process which allows us to link the initial clast and air velocities and to find an approximation to the subsequent air flow field integration of the equations of motion for clasts with a wide range of sizes densities initial speeds and initial elevation angles allows the ranges of these clasts to be found clast range data from three documented explosive eruptions are re analysed to yield initial velocities and the implications of these velocities for pre explosion pressure conditions are discussed

consistent estimates of tsunami energy show promise for improved early warning early tsunami warning critically hinges on rapid determination of the tsunami hazard potential in real time before waves inundate critical coastlines tsunami energy can quickly characterize the destructive potential of generated waves traditional seismic analysis is inadequate to accurately predict a tsunami s energy recently two independent approaches have been proposed to determine tsunami source energy one inverted from the deep ocean assessment and reporting of tsunamis dart data during the tsunami propagation and the other derived from the land based coastal global positioning system gps during tsunami generation here we focus on assessing these two approaches with data from the march 11 2011 japanese tsunami while the gps approach takes into consideration the dynamic earthquake process the dart inversion approach provides the actual tsunami energy estimation of the propagating tsunami waves both approaches lead to consistent energy scales for previously studied tsunamis encouraged by these promising results we examined a real time approach to determine tsunami source energy by combining these two methods first determine the tsunami source from the globally expanding gps network immediately after an earthquake for near field early warnings and then to refine the tsunami energy estimate from nearby dart measurements for improving forecast accuracy and early cancelations the combination of these two real time networks may offer an appealing opportunity for early determination of the tsunami threat for the purpose of saving more lives and early cancelation of tsunami warnings to avoid unnecessary false alarms

the tsunami of 26 december 2004 numerical modeling and energy considerations a numerical model for the global tsunamis computation constructed by kowalik et al 2005 is applied to the tsunami of 26 december 2004 in the world ocean from 80 s to 69 n with spatial resolution of one minute because the computational domain includes close to 200 million grid points a parallel version of the code was developed and run on a cray x1 supercomputer an energy flux function is used to investigate energy transfer from the tsunami source to the atlantic and pacific oceans although the first energy input into the pacific ocean was the primary direct wave reflections from the sri lankan and eastern shores of maldives were a larger source the tsunami traveled from indonesia around new zealand and into the pacific ocean by various routes the direct path through the deep ocean to north america carried miniscule energy while the stronger signal traveled a considerably longer distance via south pacific ridges as these bathymetric features amplified the energy flux vectors travel times for these amplified energy fluxes are much longer than the arrival of the first wave these large fluxes are organized in the wave like form when propagating between australia and antarctica the sources for the larger fluxes are multiple reflections from the seychelles maldives and a slower direct signal from the bay of bengal the energy flux into the atlantic ocean shows a different pattern since the energy is pumped into this domain through the directional properties of the source function the energy flow into the pacific ocean is approximately 75 of the total flow to the atlantic ocean in many locations along the pacific and atlantic coasts the first arriving signal or forerunner has lower amplitude than the main signal which often is much delayed understanding this temporal distribution is important for an application to tsunami warning and prediction

introduction to tsunami science ten years after the 2004 indian ocean tsunami volume i twenty papers on the study of tsunamis and respective tsunamigenic earthquakes are included in volume ii of the pageoph topical issue tsunami science ten years after the 2004 indian ocean tsunami the papers presented in this second of two special volumes of pure and applied geophysics reflect the state of tsunami science during this time including five papers devoted to new findings specifically in the indian ocean two papers compile results from global observations and eight papers cover pacific ocean studies focusing mainly on the 2011 tohoku earthquake and tsunami remaining papers in this volume describe studies in the atlantic ocean and mediterranean sea and tsunami source studies overall the volume not only addresses the pivotal 2004 indian ocean and 2011 tohoku tsunamis but also examines the tsunami hazard posed to other critical coasts in the world

numerical tsunami simulation including elastic loading and seawater density stratification systemic discrepancies between observed and modeled tsunami wave speeds were previously identified for two recent major tsunamis the 2010 maule and 2011 tohoku events to account for these discrepancies we developed a numerical tsunami propagation code solving the shallow water equation and including the effects of elastic loading of the seafloor by the tsunami as well as a linear density profile in the seawater column we show here that both effects are important to explain the commonly observed difference between observations and simulations we conclude that the density variation in the seawater column affects the wave speed without changing the waveform whereas the loading effect has an effect on the wave speed and the waveform showing a negative phase before the main arrival due to the depression of the seafloor surrounding the tsunami wave the combination of both effects is needed to achieve a better match between observations and simulations

rapid low cost photogrammetry to monitor volcanic eruptions an example from mount st helens washington usa we describe a low cost application of digital photogrammetry using commercially available photogrammetric software and oblique photographs taken with an off the shelf digital camera to create sequential digital elevation models dems of a lava dome that grew during the 2004 2008 eruption of mount st helens msh volcano renewed activity at msh provided an opportunity to devise and test this method because it could be validated against other observations of this well monitored volcano the datasets consist of oblique aerial photographs snapshots taken from a helicopter using a digital single lens reflex camera twelve sets of overlapping digital images of the dome taken during 2004 2007 were used to produce dems and to calculate lava dome volumes and extrusion rates analyses of the digital images were carried out using photogrammetric software to produce three dimensional coordinates of points identified in multiple photos the evolving morphology of the dome was modeled by comparing successive dems results were validated by comparison to volume measurements derived from traditional vertical photogrammetric surveys by the us geological survey cascades volcano observatory our technique was significantly less expensive and required less time than traditional vertical photogrammetric techniques yet it consistently yielded volume estimates within 5 of the traditional method this technique provides an inexpensive rapid assessment tool for tracking lava dome growth or other topographic changes at restless volcanoes

characterisation of the 1997 vulcanian explosions of soufriere hills volcano montserrat by video analysis the activity of convention at montserrat soufriere hills volcano montserrat during the period 1995 1999 included numerous violent explosions two major cycles of vulcanian explosions occurred in 1997 a first of 13 explosions between 4 and 12 august and a second of 75 between 22 september and 21 october the explosions were short lived events lasting a few tens of seconds during which partial fountain collapse generated pyroclastic surges and pyroclastic flows and buoyant plumes ascended 3 15 km into the atmosphere each explosion discharged on average 3 105 m3 dense rock equivalent dre of magma draining the conduit to depths of 1 2 km the paper focuses on the first few seconds of three explosions of the 75 that occurred in september october 1997 6 october 1997 at 17 50 7 october 1997 at 16 02 and 9 october 1997 at 12 32 physical parameters such as exit velocities magmatic water contents and magma pressures at fragmentation are estimated by following and modelling the ascent of individual momentum dominated finger jets visible on videos during the initial stages of each explosion the model treats each finger jet as an incompressible flow sustained by a steady flux of gas and particles during the few seconds of ascent and produces results that compare favourably with those using a multiphase compressible code run using similar eruptive parameters each explosion reveals a progressive increase in eruptive intensity with time jet exit velocities increasing from 40 m s 1 at the beginning of the explosion up to 140 m s 1 after a few seconds modelling suggests that the first magma to exit was largely degassed whereas that discharged after a few seconds contained up to 2 wt water magma overpressures up to 10 mpa are estimated to have existed in the conduit immediately prior to each explosion progressive increases in jet exit velocity with time over the first few seconds of each explosion provide direct evidence for strong pre eruptive gradients in water content and magma pressure in the upper reaches probably 100 500 m of the conduit fountain collapse occurred during the first 10 20 s of each explosion because the discharging jets had bulk densities up to 100 times that of the atmosphere and were unable to entrain enough air to become buoyant such high eruptive densities were due to the presence of partially degassed magma in the conduit

source spectrum for the algerian tsunami of 21 may 2003 estimated from coastal tide gauge data 1 on 21 may 2003 a submarine earthquake occurred near algiers producing a tsunami that propagated northward and reached the balearic islands and the levantine coast of the iberian peninsula within an hour despite that the generated tsunami was moderate sea level variations inside certain harbors at the balearic islands were significant producing severe damage to moored boats available tsunami records in the affected harbors are examined to estimate amplifications factors of arriving waves and spectral characteristics of the source comparison between background and tsunami oscillations at various sites allowed separation of the tsunami source properties from local topographic effects the fundamental period of the reconstructed source spectrum is 21 min which is in close agreement with that found by alasset et al 2006 based on modeling the tsunami initiation

the 2017 mexico tsunami record numerical modeling and threat assessment in costa rica an mw 8 2 earthquake and tsunami occurred offshore the pacific coast of mexico on 2017 09 08 at 04 49 utc costa rican tide gauges have registered a total of 21 local regional and far field tsunamis the quepos gauge registered 12 tsunamis between 1960 and 2014 before it was relocated inside a harbor by late 2014 where it registered two more tsunamis this paper analyzes the 2017 mexico tsunami as recorded by the quepos gauge it took 2 h for the tsunami to arrive to quepos with a first peak height of 9 35 cm and a maximum amplitude of 18 8 cm occurring about 6 h later as a decision support tool this tsunami was modeled for quepos in real time using commit community model interface for tsunami with the finer grid having a resolution of 1 arcsec 30 m however the model did not replicate the tsunami record well probably due to the lack of a finer and more accurate bathymetry in 2014 the national tsunami monitoring system of costa rica sinamot was created acting as a national tsunami warning center the occurrence of the 2017 mexico tsunami raised concerns about warning dissemination mechanisms for most coastal communities in costa rica due to its short travel time