TY  - JOUR
ID  - epos1677
UR  - http://doi.org/10.1007/s10950-012-9309-4
IS  - 1
A1  - Kraaijpoel, Dirk
A1  - Dost, Bernard
N2  - A number of natural gas fields in the north of the Netherlands show moderate seismicity induced by gas extraction. The gas reservoirs are located underneath a thick layer of Zechstein evaporites (salt). The presence of the salt has two important effects on the wave motions of induced events as recorded at the surface close to the epicenter. The first effect is the defocusing of seismic energy, with its implications on observed amplitudes and radiation patterns. The second effect is the relatively strong conversion from P- to S-energy at the bottom of the salt, leading to the presence of S-wave precursors. Failure to recognize these effects may lead to misinterpretation of source location and mechanism. Moreover, the S-wave precursors provide a handle to reduce uncertainty in depth estimation. We investigate the effects using moment tensor inversion and ray tracing for four recent events (M L ?=?2.6???3.5) in the Groningen field.
VL  - 17
TI  - Implications of salt-related propagation and mode conversion effects on the analysis of induced seismicity
AV  - none
EP  - 107
Y1  - 2013/01//
PB  - Springer Verlag
JF  - Journal of Seismology
KW  - Induced seismicity
KW  -  Salt
KW  -  Wave mode conversion
KW  -  Source mechanism
KW  -  S-wave precursor
SN  - 1383-4649
SP  - 95
ER  -