Near-surface geophysical investigation in Mae On, Chiang Mai, Thailand

The objective of this study is to map a sedimentary layer overlying volcanic basement in Mae On area, Chiang Mai, Thailand. Seismic reflection, multichannel analysis of surface waves and electrical resistivity surveys were conducted to provide additional supporting information in the shallow part of subsurface geometry. The deeper part information is evaluated from the previous magnetic and gravity anomaly maps. The interpretation from seismic reflection is used to constrain gravity forward modeling to obtain a pseudo-geological model. The final model presents that there are a thin Quaternary sediment layer with low electrical resistivity and seismic velocity, overlies volcanic basement with high electrical resistivity and high seismic velocities. The volcanic basement can be recognized as a heterogeneous body with horizontally characteristic layers of volcanic flows based on seismic reflection profiles. The volcanic basement underneath the sediment layer shows a high anomaly on gravity and magnetic maps.