Abstract
We present a P-wave minimum 1D velocity model for central and northern Pakistan along with station delays. The velocity model and appropriate station delays are obtained through travel time inversions as a solution of the coupled hypocenter location and velocity problem using the VELEST code. We used the arrival time observations at 25 stations of the Centre for Earthquake Studies (Islamabad) from 378 selected high quality local events with at least seven P-wave readings per event and an azimuthal gap < 180∘ from the period 2001 to 2020. The P-wave minimum 1D velocity model consists of eight layers with the depth up to 80 km. The P-wave velocity varies from 5.4 km/s at top layer up to 8.4 km/s at the bottom. The Moho boundary delineates the crust and mantle at the depth of around 50 km. The depth of the events is distributed from few kilometers up to 80 km. The station delays account for the local structure in the vicinity of the seismic station and vary between − 1.3 s and + 0.8 s. With the use of new 1D model there is significant improvement in RMS value and hypocentral parameters. Especially there is significant improvement in the depth. The model will be useful in high precision location of the local events and in filtering the data for outlier observations. The model may also be used as an initial reference model for 3D tomography.
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Acknowledgements
We are thankful to the staff of Centre for Earthquake Studies who helped in data preparation. We are very much thankful for the helpful review of Prof. Eddi Kissling, whose suggestions improved the overall quality of the paper. We are also thankful to an anonymous reviewer who also provided helpful suggestions. Most of the figures were made using the Generic Mapping Tools by Wessel and Smith (1995).
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Soomro, R., Iqbal, S., Shah, M. et al. P-wave minimum 1D velocity model for central and northern Pakistan. J Seismol 26, 1039–1049 (2022). https://doi.org/10.1007/s10950-022-10111-x
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DOI: https://doi.org/10.1007/s10950-022-10111-x