Crustal uplift and sea level rise in northern Cascadia from GPS, absolute gravity, and tide gauge data

Mazzotti, S.; Lambert, A.; Courtier, N.; Nykolaishen, L.; Dragert, H.

doi:10.1029/2007gl030283

Cited by 44 publications

(57 citation statements)

References 19 publications

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“…For the 1962 earthquake in Alaska, the ratio between coseismic gravity and height changes is closer to the Bouguer ratio than to the free-air gradient (BARNES, 1966). For the Cascadia subduction zone, MAZZOTTI et al (2007) found a ratio of -0.24 lGal mm -1 close to the predicted value of -0.19 lGal mm -1 from 10 years of continuous GPS and AG measurements. However, an offset between gravity and height variations is observed.…”

Section: Introductionsupporting

confidence: 51%

“…This holds for all campaigns of applied geophysics because gravity has to be corrected for elevation changes in various ways (e.g., free air correction, Bouguer correction). In solid Earth geophysics, collocated gravity and position measurements are also strongly favored in studies dealing with postglacial rebound (PGR) (EKMAN and MÄ KINEN, 1996;LAMBERT et al, 2001LAMBERT et al, , 2006MÄ KINEN et al, 2007), tectonic motions (JACHENS, 1978;KARNER and WATTS, 1983;BALLU et al, 2003;TEFERLE et al, 2006;MAZZOTTI et al, 2007), coseismic deformation (BARNES, 1966;TANAKA et al, 2001;IMANISHI et al, 2004), volcanic activity (JOUSSET et al, 2000;FURUYA et al, 2003) or surface loading processes ZERBINI et al, 2004;NICOLAS et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

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Variability of the Gravity-to-Height Ratio Due to Surface Loads

Linage

Hinderer

Boy

2009

Pure appl. geophys.

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We study the ratio between the gravity variation and vertical displacement on the surface of a self-gravitating earth model when a surface load is applied. We adopt a theoretical and numerical point of view, excluding any observations. First, we investigate the spectral behavior of the ratio of the harmonic components of the gravity variation and vertical displacement. Then, we model the gravity-to-height ratio for different surface loads (continental hydrology, atmospheric pressure, ocean tides) using outputs of global numerical models in order to relate the predicted spatial values to theoretical mean values deduced from the spectral domain. For locations inside loaded areas, the ratio is highly variable because of the Newtonian attraction of the local masses and depends on the size of the load. For the hydrological loading (soil moisture and snow), the mean ratio over the continents is -0.87 lGal mm -1 , but increases with decreasing size of the river basins. For the atmospheric loading, assuming an inverted-barometer response of the ocean, the ratio is positive, with larger values for high latitudes (0.49 lGal mm -1 )-particularly on the coasts-than for lower latitudes (0.30 lGal mm -1 ). The ratio, however, is much less variable outside the loaded areas: in desert areas such as the Sahara and Arabia, its mean value is -0.28 lGal mm -1 . For the ocean tidal loading, we find a mean ratio of -0.26 lGal mm -1 over the continents for the diurnal tidal waves. Both results are close to the theoretical mean value of -0.26 lGal mm -1 combining elastic and remote attraction contributions.

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Section: Introductionsupporting

confidence: 51%

Section: Introductionmentioning

confidence: 99%

Variability of the Gravity-to-Height Ratio Due to Surface Loads

Linage

Hinderer

Boy

2009

Pure appl. geophys.

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“…In addition, secular trends with approximately − 0.2, 0.9 and 0.5 μGal/year were detected at OMZ, KKG and TYH, respectively, for the whole observation periods. A similar unexplained positive long-term gravity trend of ~ 0.5 μGal/year is seen also in the Cascadia subduction zone (Mazzotti et al 2007).…”

Section: Discussionsupporting

confidence: 50%

“…However, only a small number of papers have reported inter-seismic gravity changes based on μGal-level precisions (Mazzotti et al 2007;Tanaka et al 2010;Van Camp et al 2011) (1 μGal = 10 −8 ms −2 ). Observed temporal gravity changes catch underground density redistributions, which can give us information that cannot be obtained from surface displacements.…”

Section: Introductionmentioning

confidence: 99%

Temporal gravity anomalies observed in the Tokai area and a possible relationship with slow slips

Tanaka

Suzuki

Imanishi

et al. 2018

Earth Planets Space

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The water in Earth's mantle is closely related with plate subduction and volcanism. Recent studies revealed that the mantle wedge corner at approximately 30 km depth holds high-pressure water, where many slow earthquakes occur.To quantify how such water behaves during slow earthquakes helps us understand the mechanisms of these earthquakes and (eventually) a part of the long-term water cycle between the interior and surface of the Earth. However, little evidence has thus far been reported on the transient flows of such deep water. Here, we report anomalous, negative mass anomalies during two recent long-term slow slip events in the Tokai area in Japan, which were detected by absolute gravity measurements over 20 years. We present a poroelastic fluid flow model assuming a localized deformation within the fault fracture zone. The model can reproduce the gravity change with a permeability range between those suggested by laboratory experiments and numerical simulations of slow earthquakes.

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“…This ratio is a function of the wavelength, the rheology and the history of the deformed layers and depends on the position of the load and on geodynamic process, so it depends on whether specific sites are located inside formerly glaciated areas, or peripheral, or in between; on how wide the respective ice sheet was, and whether there is elastic response due to contemporary ice changes, earthquakes or tectonic processes [Rundle, 1978;Wahr et [23] The ratio ( _ g/_ z) has not yet been experimentally determined with the required accuracy to allow discrimination between the modeled values [Ekman and Mäkinen, 1996;Lambert et al, 2001;Mazzotti et al, 2007]. For comparison, the observed gravity rates of change, converted into vertical velocities using the published plausible ratios are also shown in Figure 3b by the black (_ z observed = − _ g observed /1.0) and blue (_ z observed = − _ g observed /2.6) symbols, providing upper and lower values for the possible vertical velocities inferred from our AG measurements.…”

Section: Gravity Rates Of Change Versus Vertical Velocitiesmentioning

confidence: 99%

Repeated absolute gravity measurements for monitoring slow intraplate vertical deformation in western Europe

et al. 2011

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In continental plate interiors, ground surface movements are at the limit of the noise level and close to or below the accuracy of current geodetic techniques. Absolute gravity measurements are valuable to quantify slow vertical movements, as this instrument is drift free and, unlike GPS, independent of the terrestrial reference frame. Repeated absolute gravity (AG) measurements have been performed in Oostende (Belgian coastline) and at eight stations along a southwest‐northeast profile across the Belgian Ardennes and the Roer Valley Graben (Germany), in order to estimate the tectonic deformation in the area. The AG measurements, repeated once or twice a year, can resolve elusive gravity changes with a precision better than 3.7 nm/s2/yr (95% confidence interval) after 11 years, even in difficult conditions. After 8–15 years (depending on the station), we find that the gravity rates of change lie in the [−3.1, 8.1] nm/s2/yr interval and result from a combination of anthropogenic, climatic, tectonic, and glacial isostatic adjustment (GIA) effects. After correcting for the GIA, the inferred gravity rates and consequently, the vertical land movements, reduce to zero within the uncertainty level at all stations except Jülich (because of man‐induced subsidence) and Sohier (possibly, an artifact because of the shortness of the time series at that station).

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Crustal uplift and sea level rise in northern Cascadia from GPS, absolute gravity, and tide gauge data

Cited by 44 publications

References 19 publications

Variability of the Gravity-to-Height Ratio Due to Surface Loads

Variability of the Gravity-to-Height Ratio Due to Surface Loads

Temporal gravity anomalies observed in the Tokai area and a possible relationship with slow slips

Repeated absolute gravity measurements for monitoring slow intraplate vertical deformation in western Europe

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