Record details

Title
    Seismicity-based estimation of the driving fluid pressure in the case of swarm activity in Western Bohemia
Author
    Dahm, T.
    Fischer, Tomáš
    Hainzl, S.
Language
    anglicky
Publication type
    článek v periodiku
Source title - serial
    Geophysical Journal International
Vol./nr.
    Roč. 191, č. 1
Pages
    11
Year
    2012
Thesaurus term
    Earthquake dynamics
    Earthquake source observations
    Fracture and flow
    Statistical seismology
Keyword
    Activity
    Bohemia
    Case
    Driving
    Estimation
    Fluid
    Pressure
    Seismicity-based
    Swarm
    Western
Abstract (in english)
   Two recent major swarms in Western Bohemia occurred in the years 2000 and 2008 within almost the same portion of a fault close to Novy Kostel. Previous analysis of the year 2000 earthquake swarm revealed that fluid intrusion seemed to initiate the activity whereas stress redistribution by the individual swarm earthquakes played a major role in the further swarm evolution. Here we analyse the new swarm, which occurred in the year 2008, with regard to its correlation to the previous swarm as well its spatiotemporal migration patterns. We find that (i) the main part of the year 2008 activity ruptured fault patches adjacent to the main activity of the swarm 2000, but that also (ii) a significant overlap exists where earthquakes occurred in patches in which stress had been already released by precursory events; (iii) the activity shows a clear migration which can be described by a 1-D (in up-dip direction) diffusion process; (iv) the migration pattern can be equally well explained by a hydr
   ofracture growth, which additionally explains the faster migration in up-dip compared to the down-dip direction as well as the maximum up-dip extension of the activity. We use these observations to estimate the underlying fluid pressure change in two different ways: First, we calculate the stress changes induced by precursory events at the location of each swarm earthquake assuming that observed stress deficits had to be compensated by pore pressure increases; and secondly, we estimate the fluid overpressure by fitting a hydrofracture model to the asymmetric seismicity patterns. Both independent methods indicate that the fluid pressure increase was initially up to 30 MPa.
Contributor
    UK Praha, Přírodovědecká fakulta
Contributor code
    UK, PřF
Source format
    R
Import date
    27. 4. 2014