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SUMMARY:Water can move mountains: hydrologically induced deformation in th
 e Apennines (Italy) and Sierra Nevada (California) observed from GNSS data
  - Francesca Silverii\, Istituto Nazionale di Geofisica e Vulcanologia (IN
 GV\, Italy)
DTSTART:20241030T140000Z
DTEND:20241030T150000Z
UID:TALK221383@talks.cam.ac.uk
CONTACT:Adriano Gualandi
DESCRIPTION:The redistribution of water masses due to temporal variations 
 of hydrological conditions can produce observable deformation of the shall
 ow crust. Space geodetic techniques\, such as GNSS\, have provided a consi
 derable improvement in terms of data accuracy and spatial and temporal res
 olution for the detection and investigation of this kind of deformation. I
 n particular\, in the areas where snow and water accumulate for long perio
 ds\, such as mountainous areas and aquifers\, relatively high deformation 
 (up to several millimeters in the vertical and horizontal components) has 
 been observed.\nIn this work\, we analyze two areas which are interesting 
 from both hydrological and tectonic point of views. The Apennines represen
 t one of the most seismic areas of Italy. The karst aquifers hosted in thi
 s mountain range are able to store huge quantities of groundwater and prov
 ide water supply for large cities like Rome and Naples.  The Sierra Nevada
  provides most of California’s water supply and is located right next to
  a large and still active volcanic system that includes Long Valley Calder
 a. Combining displacement data from dense permanent GNSS networks with var
 ious hydrological records we analyze these two case-studies to deconvolve 
 the transient\, hydrological deformation from steady-state\, tectonic defo
 rmation.\nWe show that the karst aquifers of the Apennines deform in respo
 nse to seasonal and interannual variations of groundwater content\, produc
 ing a visible transient signal in the time series of the surrounding GNSS 
 sites. This suggests that the large karst aquifers of this region alternat
 ely expand and contract in response to higher/lower groundwater content in
  the aquifers and\, consequently to variable hydraulic head. Thanks to the
  availability of a dense GNSS network and different kinds of hydrological 
 data we focus on the process causing the observed deformation. \nSierra Ne
 vada represents a geophysically complex area due to the presence of an act
 ive magmatic system\, tectonic motion with associated seismicity and the h
 ydrological forcing associated with the huge amount of precipitation that 
 falls on the Sierra Nevada and its spatiotemporal variability. These super
 imposed tectonic and non-tectonic processes cause composite deformation in
 cluding long-term tectonic motion\, episodic inflation of the resurgent do
 me and variable seasonal and multi-year displacements from surface water l
 oading and subsurface discharge/recharge.\nWe observe a clear vertical def
 ormation pattern whose spatiotemporal variability is likely related to sur
 face loading acting both at the large (regional or continental) and local 
 scales. We highlight anomalous horizontal deformation in the GNSS sites on
  the Sierra Nevada range front\, showing its clear correlation with spring
  discharge. We investigate possible causes of this significant deformation
 \, including response to snowpack loading and the influence of groundwater
  recharge.
LOCATION:Wolfson Lecture Theatre
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