[Forum SIS] Avviso seminario - N. Dudley Ward - 20/07 - IMATI, Milano

[Raffaele Argiento]

Venerdì 20 Luglio, alle ore 11.00 presso la sede di Milano dell'IMATI,
in via Bassini 15, aula Pentagonale.

Il Dott. Nick Dudley Ward (Otago Computational Modelling Group Ltd, New Zealand)
terrà il seminario dal Titolo: "Earthquakes, liquefaction and Christchurch's 
artesian aquifers"

Tutti gli interessati sono invitati a partecipare.


Abstract:  Since the Mw 7.1 Darfield (Canterbury) earthquake on 
4 September 2010, 4.35 a.m. (local time), Christchurch and its environs
have experienced an intense sequence of earthquakes and aftershocks. 
Most devastating was the Mw 6.2 Christchurch earthquake on 
22 February 2011 at 12.51 p.m. which resulted in significant destruction and 
damage, injuries and 185 deaths. Of similar magnitude we mention the
Mw 6.0 aftershock on 13 June 2011 at 2.20 p.m. and its Mw 5.6 precursor 
at 1 p.m. which further damaged or destroyed structures already damaged 
from previous earthquakes, ruptured infrastructure and caused power outages.

The aim of this talk is twofold.  First we present an analysis of groundwater 
level responses to the main destructive Canterbury/Christchurch earthquakes.
The local environmental authority has a distributed network of 257 monitoring 
wells in the Canterbury region, of which 161 contain relevant data collected 
at 15 minute intervals.  We quantify groundwater responses with a simple model
which differentiates between short-term earthquake induced responses (spike) 
and longer-term change (offset). The most significant feature of our 
analysis is the consistent pattern of groundwater response to the 
earthquakes for wells in the coastal confined (artesian) aquifers: deeper 
wells correlate with negative offset and shallower wells correlate 
with positive offset.
This is consistent with the upwards vertical movement  of water 
(on the time scale of a  seismic shock). We consider the hydrological 
and engineering consequences.

Second we consider some inverse problems for groundwater. For clarity we 
focus on a classical problem of groundwater engineering, viz. that of 
determining aquifer parameters from pumping test data.  We consider a 
model with spatially distributed parameters.  Using a (proper) prior model
of Kaipio and Somersalo and an adaptive MCMC algorithm of Cui we quantify
parameter uncertainty.





--
=======================================
Raffaele Argiento                       
IMATI-CNR, Via Bassini 15, 20133 Milano 
Tel. +39 02 23699527                    
Fax. +39 02 23699538                    
e-mail: raffaele a mi.imati.cnr.it        
========================================