TY  - JOUR
A1  - Negi, Sanjay S.
A1  - Paul, Ajay
A1  - Cesca, Simone
A1  - Kamal, 
A1  - Kriegerowski, Marius
A1  - Mahesh, P.
A1  - Gupta, Sandeep
T1  - Crustal velocity structure and earthquake processes of Garhwal-Kumaun Himalaya: Constraints from regional waveform inversion and array beam modeling
JF  - Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth
N2  - In order to understand present day earthquake kinematics at the Indian plate boundary, we analyse seismic broadband data recorded between 2007 and 2015 by the regional network in the Garhwal-Kumaun region, northwest Himalaya. We first estimate a local 1-D velocity model for the computation of reliable Green's functions, based on 2837 P-wave and 2680 S-wave arrivals from 251 well located earthquakes. The resulting 1-D crustal structure yields a 4-layer velocity model down to the depths of 20 km. A fifth homogeneous layer extends down to 46 km, constraining the Moho using travel-time distance curve method. We then employ a multistep moment tensor (MT) inversion algorithm to infer seismic moment tensors of 11 moderate earthquakes with Mw magnitude in the range 4.0–5.0. The method provides a fast MT inversion for future monitoring of local seismicity, since Green's functions database has been prepared. To further support the moment tensor solutions, we additionally model P phase beams at seismic arrays at teleseismic distances. The MT inversion result reveals the presence of dominant thrust fault kinematics persisting along the Himalayan belt. Shallow low and high angle thrust faulting is the dominating mechanism in the Garhwal-Kumaun Himalaya. The centroid depths for these moderate earthquakes are shallow between 1 and 12 km. The beam modeling result confirm hypocentral depth estimates between 1 and 7 km. The updated seismicity, constrained source mechanism and depth results indicate typical setting of duplexes above the mid crustal ramp where slip is confirmed along out-of-sequence thrusting. The involvement of Tons thrust sheet in out-of-sequence thrusting indicate Tons thrust to be the principal active thrust at shallow depth in the Himalayan region. Our results thus support the critical taper wedge theory, where we infer the microseismicity cluster as a result of intense activity within the Lesser Himalayan Duplex (LHD) system.
KW  - Critical taper wedge
KW  - Lesser Himalayan Duplex
KW  - Out-of-sequence thrust
Y1  - 2017
U6  - https://doi.org/10.1016/j.tecto.2017.05.007
SN  - 0040-1951
SN  - 1879-3266
VL  - 712
SP  - 45
EP  - 63
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - GEN
A1  - Dahm, Torsten
A1  - Becker, Dirk
A1  - Bischoff, Monika
A1  - Cesca, Simone
A1  - Dost, B.
A1  - Fritschen, R.
A1  - Hainzl, Sebastian
A1  - Klose, C. D.
A1  - Kuhn, D.
A1  - Lasocki, S.
A1  - Meier, Thomas
A1  - Ohrnberger, Matthias
A1  - Rivalta, Eleonora
A1  - Wegler, Ulrich
A1  - Husen, Stephan
T1  - Recommendation for the discrimination of human-related and natural seismicity
T2  - Journal of seismology
N2  - Various techniques are utilized by the seismological community, extractive industries, energy and geoengineering companies to identify earthquake nucleation processes in close proximity to engineering operation points. These operations may comprise fluid extraction or injections, artificial water reservoir impoundments, open pit and deep mining, deep geothermal power generations or carbon sequestration. In this letter to the editor, we outline several lines of investigation that we suggest to follow to address the discrimination problem between natural seismicity and seismic events induced or triggered by geoengineering activities. These suggestions have been developed by a group of experts during several meetings and workshops, and we feel that their publication as a summary report is helpful for the geoscientific community. Specific investigation procedures and discrimination approaches, on which our recommendations are based, are also published in this Special Issue (SI) of Journal of Seismology.
KW  - Triggered seismicity
KW  - Induced seismicity
Y1  - 2013
U6  - https://doi.org/10.1007/s10950-012-9295-6
SN  - 1383-4649
VL  - 17
IS  - 1
SP  - 197
EP  - 202
PB  - Springer
CY  - Dordrecht
ER  -