Contemporary vertical surface displacements in Yellowstone National Park

Abstract

Relative vertical displacements and average relative vertical velocities have been determined for bench marks located throughout Yellowstone National Park (YNP) by comparing geodetic leveling measurements made in 1923 (second order), 1936 (third order), 1941 (third order), 1955 (third order), 1960 (first order), and 1975–1977 (first order). The 1923–1975 data indicate uplift greater than 400 mm (7.7 mm/yr) of an area approximately 15–20 km wide and at least 40 km long which is centered along the northeast trending axis of the 600,000‐year‐old Yellowstone caldera; the maximum 1923–1975 vertical displacement in this area is 726 mm (14.0 mm/yr). The existence of a well‐defined and untilted Yellowstone Lake terrace implies that the 1923–1975 average vertical velocities cannot have been maintained for more than a few hundred years. The 1955–1977 data from central YNP indicate that the northeastern caldera half has risen relative to the southwestern half at an average velocity of about 8 mm/yr; a similar bias is present in the 1923–1975 data but it is less pronounced. The 1923–1960 and 1960–1975 data from northwestern YNP, and a 200 mm depression in the 1923–1975 data near Norris Junction, may be interpreted in terms of deformation associated with the 1959 Hebgen Lake earthquake and the 1975 Yellowstone Park earthquake. A composite profile of the 1936–1977 and 1941–1977 average vertical velocity data which skirts the edge of the Yellowstone caldera in northeastern YNP is most easily explained as the result of random leveling error and/or bench mark instabilities. The apparent youth of the 1923–1975 Yellowstone uplift and its close association with the Yellowstone caldera suggest that the most likely cause of the uplift is a recent (not more than 500 years ago) influx of molten material into the upper crust beneath the caldera.

Post-glacial inflation-deflation cycles, tilting, and faulting in the Yellowstone Caldera based on Yellowstone Lake shorelines

“…16A). Uplift or inflation because of magma intrusion is quite plausible (Pelton and Smith, 1982;Dzurisin and others, 1994). Modeling indicates that the historic inflation is consistent with a volume expansion involving either magmatic or hydrothermal fluids, primarily in the 3-6 km depth range (Vasco and others, 1990), or 8 km (Wicks and others, 1998).…”

“…Because Yellowstone is an active volcanic field, a magmatic explanation is obviously plausible (Pelton and Smith, 1982;Dzurisin and others, 1994). The inflation has been modeled with the largest volume expansions in the 3.0-6.0 km depth range (Vasco and others, 1990).…”

“…4), also argues against isostatic rebound. Pelton and Smith (1982), Caldera Unrest 3-02.doc, Professional Paper, Ken Pierce, , page 18…”

Geologic field-trip guide to the volcanic and hydrothermal landscape of the Yellowstone Plateau

“…After resurveying the extensive network of leveling benchmarks for the vertical component of deformation in , 1976, Pelton and Smith (1982 discovered an extraordinary 740 millimeters (mm) of uplift in a ~50 year time period, averaging ~15 millimeters per year (mm/yr). Subsequent leveling found different rates of uplift in the northeast and southwest parts of the caldera continuing though 1984 (Dzurisin and others, 1990).…”

InSAR decorrelation to assess and prevent volcanic risk

“…This work studies the correlation of pairs of SAR images covering the Yellowstone caldera, focusing on the influence of surface and climate conditions, especially snow coverage and temperature; furthermore, the effects of the acquisition band (the wavelength of the signal) on correlation are taken into account, comparing L-band and C-band images. In the past few years the restless uplift and subsidence of this mega volcano has drawn the attention of scientists: the Yellowstone caldera has been the object of many studies and the InSAR technique has been largely used to detect its ground movements [Pelton and Smith, 1982]. All the chosen images/satellites (both ascending and descending) are selected considering the date of acquisition between a 4 years span (initially 1992-1996 and later also 2002-2006), possibly sampling all the seasons, and with an area covering most of the caldera.…”