Streamflow and Water Well Responses to Earthquakes Montgomery, David R.; Manga, Michael
Science (American Association for the Advancement of Science),
06/2003, Letnik:
300, Številka:
5628
Journal Article
Recenzirano
Odprti dostop
Earthquake-induced crustal deformation and ground shaking can alter stream flow and water levels in wells through consolidation of surficial deposits, fracturing of solid rocks, aquifer deformation, ...and the clearing of fracture-filling material. Although local conditions affect the type and amplitude of response, a compilation of reported observations of hydrological response to earthquakes indicates that the maximum distance to which changes in stream flow and water levels in wells have been reported is related to earthquake magnitude. Detectable streamflow changes occur in areas within tens to hundreds of kilometers of the epicenter, whereas changes in groundwater levels in wells can occur hundreds to thousands of kilometers from earthquake epicenters.
The existence, spatial distribution, and style of volcanism on terrestrial planets is an expression of their internal dynamics and evolution. On Earth a physical link has been proposed between hot ...spots, regions with particularly persistent, localized, and high rates of volcanism, and underlying deep mantle plumes. Such mantle plumes are thought to be constructed of large spherical heads and narrow trailing conduits. This plume model has provided a way to interpret observable phenomena including the volcanological, petrological, and geochemical evolution of ocean island volcanoes, the relative motion of plates, continental breakup, global heat flow, and the Earth's magnetic field within the broader framework of the thermal history of our planet. Despite the plume model's utility the underlying dynamics giving rise to hot spots as long‐lived stable features have remained elusive. Accordingly, in this review we combine results from new and published observational, analog, theoretical, and numerical studies to address two key questions: (1) Why might mantle plumes in the Earth have a head‐tail structure? (2) How can mantle plumes and hot spots persist for large geological times? We show first that the characteristic head‐tail structure of mantle plumes, which is a consequence of hot upwellings having a low viscosity, is likely a result of strong cooling of the mantle by large‐scale stirring driven by plate tectonics. Second, we show that the head‐tail structure of such plumes is a necessary but insufficient condition for their longevity. Third, we synthesize seismological, geodynamic, geomagnetic, and geochemical constraints on the structure and composition of the lowermost mantle to argue that the source regions for most deep mantle plumes contain dense, low‐viscosity material within D″ composed of partial melt, outer core material, or a mixture of both (i.e., a “dense layer”). Fourth, using results from laboratory experiments on thermochemical convection and new theoretical scaling analyses, we argue that the longevity of mantle plumes in the Earth is a consequence of the interactions between plate tectonics, core cooling, and dense, low‐viscosity material within D″. Conditions leading to Earth‐like mantle plumes are highly specific and may thus be unique to our own planet. Furthermore, long‐lived hot spots should not a priori be anticipated on other terrestrial planets and moons. Our analysis leads to self‐consistent predictions for the longevity of mantle plumes, topography on the dense layer, and composition of ocean island basalts that are consistent with observations.
One of the more distinctive features of many ignimbrites is the presence of large lithics (some greater than meter scale) and pumices that have been transported great distances (>10 km) from the ...eruptive vent, sometimes over steep terrain and expanses of water. In many cases, these particles have been transported much further than can be explained by aerodynamic forces and ballistic trajectories. We examine the forces responsible for transport of large clasts and examine in detail the momentum transfer occurring when particles interact with their boundaries. We performed a suite of experiments and numerical simulations to quantify the mass and momentum transfer that occurs when particles interact with a pumice bed substrate and with water substrate, two geologically motivated flow end‐members. We find that clasts transported in dilute currents are particularly sensitive to the nature of the boundary, and while large particles can skip several times on a water substrate, they travel less far than particles that impact pumice bed substrates. All else being equal, large particles in dense pyroclastic density currents are themselves relatively insensitive to the details of their boundaries; however, one of the most important ways boundary conditions influence large particles is not through direct interaction but by changing the local concentration of fine particles. Momentum transfer from fine particles to large particles appears to be required to transport large clasts great distances. If initially dense flows become dilute during transport, then the transport capacity of large particles in the flow is substantially decreased.
The seismometer deployed by the InSight lander measured the seismic velocity of the Martian crust. We use a rock physics model to interpret those velocities and constrain hydrogeological properties. ...The seismic velocity of the upper ∼10 km is too low to be ice‐saturated. Hence there is no cryosphere that confines deeper aquifers and possibly no aquifers locally. An increase in seismic velocity at depths of ∼10 km could be explained by a few volume percent of mineral cement (1%–5%) in pore space and may document the past depth of aquifers.
Plain Language Summary
Large amounts of water may be stored in the Martian crust and episodically released to flood the surface. Where this water exists, and even why, is uncertain. The seismometer on the InSight lander measured the velocity of seismic waves in the Martian crust. The presence of ice and water affects seismic velocity. We argue that the measurements preclude a layer of ice‐filled crust that confines liquid water in an aquifer.
Key Points
We interpret the seismic wave velocity of the Martian crust measured by InSight
We quantity the effects of ice and water on seismic velocity using a rock physics model
Measurements preclude a layer of ice‐filled crust that confines liquid water in an aquifer
Primordial metallic melt in the deep mantle Zhang, Zhou; Dorfman, Susannah M.; Labidi, Jabrane ...
Geophysical research letters,
28 April 2016, Letnik:
43, Številka:
8
Journal Article
Recenzirano
Odprti dostop
Seismic tomography models reveal two large low shear velocity provinces (LLSVPs) that identify large‐scale variations in temperature and composition in the deep mantle. Other characteristics include ...elevated density, elevated bulk sound speed, and sharp boundaries. We show that properties of LLSVPs can be explained by the presence of small quantities (0.3–3%) of suspended, dense Fe‐Ni‐S liquid. Trapping of metallic liquid is demonstrated to be likely during the crystallization of a dense basal magma ocean, and retention of such melts is consistent with currently available experimental constraints. Calculated seismic velocities and densities of lower mantle material containing low‐abundance metallic liquids match the observed LLSVP properties. Small quantities of metallic liquids trapped at depth provide a natural explanation for primitive noble gas signatures in plume‐related magmas. Our model hence provides a mechanism for generating large‐scale chemical heterogeneities in Earth's early history and makes clear predictions for future tests of our hypothesis.
Key Points
A 0.3–3% metallic melt can produce the features of the large low shear velocity provinces
Trapping of metallic melt is likely during the crystallization of a dense basal magma ocean
Large low shear velocity provinces can become a primordial geochemical mantle reservoir
Geysers episodically erupt liquid and vapor. Despite two centuries of scientific study, basic questions persist-why do geysers exist? What determines eruption intervals, durations, and heights? What ...initiates eruptions? Through monitoring eruption intervals, analyzing geophysical data, taking measurements within geyser conduits, performing numerical simulations, and constructing laboratory models, some of these questions have been addressed. Geysers are uncommon because they require a combination of abundant water recharge, magmatism, and rhyolite flows to supply heat and silica, and large fractures and cavities overlain by low-permeability materials to trap rising multiphase and multicomponent fluids. Eruptions are driven by the conversion of thermal to kinetic energy during decompression. Larger and deeper cavities permit larger eruptions and promote regularity by isolating water from weather variations. The ejection velocity may be limited by the speed of sound of the liquid + vapor mixture.
In the past century, most eruptions of Steamboat Geyser in Yellowstone National Park's Norris Geyser Basin were mainly clustered in three episodes: 1961–1969, 1982–1984, and ongoing since 2018. These ...eruptive episodes resulted in extensive disturbance to surrounding trees. To characterize tree response over time as an indicator of geyser activity adjustments to climate variability, aerial and ground images were analyzed to document changes in tree coverage around the geyser since 1954. Radiocarbon dating of silicified tree remnants from within 14 m of the geyser vent was used to examine geyser response to possible variations in decadal to centennial precipitation patterns. We searched for atypical or absent growth rings in cores from live trees in years associated with large geyser eruptions. Photographs indicate that active eruptive phases have adversely affected trees up to 30 m from the vent, primarily in the dominant downwind direction. Radiocarbon dates indicate that the geyser formed before 1878, in contrast to the birthdate reported in historical documents. Further, the ages of the silicified trees cluster within three episodes that are temporally correlated with periods of relative drought in the Yellowstone region during the 15th–17th centuries. The discontinuous growth of trees around the geyser suggests that changes in eruptive patterns occur in response to decadal to multidecadal droughts. This inference is supported by the lack of silicified specimens with more than 20 annual rings and by the existence of atypical or missing rings in live trees during periods of extended geyser activity.
Plain Language Summary
Steamboat Geyser, in Yellowstone National Park's Norris Geyser Basin, has the tallest eruptions among the world's active geysers. To examine whether eruptions impact trees in the vicinity of the geyser, we analyzed aerial photos acquired since 1954 which indicate that prior periods of frequent eruptions have adversely affected trees up to 30 m from the vent, primarily in the dominant wind direction. To examine if the limited availability of water may have caused the geyser to stop erupting in past centuries, we dated silicified tree remnants with radiocarbon. Results suggest that trees were growing near Steamboat during three periods when the geyser was not erupting because of prolonged droughts in the Yellowstone region during the 15th–17th centuries. This inference is supported by observations that none of the silicified tree specimens had more than 20 annual rings, implying that the trees did not grow for long periods, and by the presence of atypical or missing rings in live trees during periods of geyser activity.
Key Points
Aerial photos indicate that recent eruptive phases of Steamboat Geyser have adversely impacted trees up to 30 m from the vent
14C dates of silicified trees cluster in three periods that temporally correlate with regional droughts during the 15th–17th centuries
Atypical or absent tree‐rings suggest that prolonged eruption episodes impacted tree growth around Steamboat Geyser
Coordination numbers in natural beach sand Wright, Vanshan; Ferrick, Amy; Manga, Michael ...
EPJ Web of Conferences,
01/2021, Letnik:
249
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
Coordination number controls elastic moduli, seismic velocity, and force transmission in sands and is thus a critical factor controlling the resistance of sands to deformation. Previous studies ...quantified relationships between coordination number, porosity, grain size, sphericity, and effective stress in pluviated or modeled sands. Here, we determine if these relationships hold in naturally-deposited beach sands. We collect samples while preserving their microstructures and use x-ray computed microtomography images to characterize grain properties. Similar to pluviated and modeled sand studies, we find that average coordination numbers and porosities for freshly deposited natural sands are 8.1 ± 2.8 and 0.37 ± 0.01, respectively. The range and standard deviation in coordination numbers of the natural beach sands are, however, significantly higher than observed in pluviated and modeled sand studies. At the same effective stress and porosities, coordination number is linearly proportional to grain surface area except for the smallest and largest grains. Coordination number depends non-linearly on sphericity. We attribute the higher ranges and standard deviations of coordination numbers in the natural sands to its broader grain size distribution, and we propose that the largest grains limit grain rearrangement, which influences spatial distributions of coordination numbers in natural sands.
Despite more than 200years of scientific study, the internal dynamics of geyser systems remain poorly characterized. As a consequence, there remain fundamental questions about what processes initiate ...and terminate eruptions, and where eruptions begin. Over a one-week period in October 2012, we collected down-hole measurements of pressure and temperature in the conduit of an exceptionally regular geyser (132s/cycle) located in the Chilean desert. We identified four stages in the geyser cycle: (1) recharge of water into the conduit after an eruption, driven by the pressure difference between water in the conduit and in a deeper reservoir; (2) a pre-eruptive stage that follows the recharge and is dominated by addition of steam from below; (3) the eruption, which occurs by rapid boiling of a large mass of water at the top of the water column, and decompression that propagates boiling conditions downward; and (4) a relaxation stage during which pressure and temperature decrease until conditions preceding the recharge stage are restored. Eruptions are triggered by the episodic addition of steam coming from depth, suggesting that the dynamics of the eruptions are dominated by geometrical and thermodynamic complexities in the conduit and reservoir. Further evidence favoring the dominance of internal processes in controlling periodicity is also provided by the absence of responses of the geyser to environmental perturbations (air pressure, temperature and probably also Earth tides).
•The eruption is characterized by boiling at the top of the water column and downward propagation of boiling conditions.•Heat released by periodic addition of steam warms water in the conduit.•The geyser cycle is not affected by environmental perturbations (air pressure, air temperature and probably also Earth tides), indicating that processes in the geyser's reservoir control periodicity.
On May 29th 2006 a mud volcano, later to be named ‘Lusi’, started to form in East Java. It is still active and has displaced >
30,000 people. The trigger mechanism for this, the world's largest and ...best known active mud volcano, is still the subject of debate. Trigger mechanisms considered here are (a) the May 27th 2006 Yogyakarta earthquake, (b) the drilling of the nearby Banjar Panji-1 gas exploration well (150 m away), and (c) a combination of the earthquake and drilling operations. We compare the distance and magnitude of the earthquake with the relationship between the distance and magnitude of historical earthquakes that have caused sediment liquefaction, or triggered the eruption of mud volcanoes or caused other hydrological responses. Based on this comparison, an earthquake trigger is not expected. The static stress changes caused by the rupture of the fault that created the Yogyakarta earthquake are a few tens of Pascals, much smaller than changes in stress caused by tides or variations in barometric pressure. At least 22 earthquakes (and possibly hundreds) likely caused stronger ground shaking at the site of Lusi in the past 30 years without causing an eruption. The period immediately preceding the eruption was seismically quieter than average and thus there is no evidence that Lusi was “primed” by previous earthquakes. We thus rule out an earthquake-only trigger. The day before the eruption started (May 28th 2006), as a result of pulling the drill bit and drill pipe out of the hole, there was a significant influx of formation fluid and gas. The monitored pressure after the influx, in the drill pipe and annulus showed variations typical of the leakage of drilling fluid into the surrounding sedimentary rock strata. Furthermore we calculate that the pressure at a depth of 1091 m (the shallowest depth without any protective steel casing) exceeded a critical level after the influx occurred. Fractures formed due to the excess pressure, allowing a fluid-gas-mud mix to flow to the surface. With detailed data from the exploration well, we can now identify the specific drilling induced phenomena that caused this man-made disaster.
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