Shear-wave velocity (v s) structures beneath two seismic stations, JJU and JJB on the flanks of the volcano Halla on Jeju island, Korea, were estimated by receiver-function inversion and H-κ stacking applied to 150 teleseismic events (M W ≥ 5.5) recorded since 2007. P S waves converted at the Moho discontinuity does not appear clearly for northwesterly back-azimuths (207 ~ 409 o , average 308 o) at station JJU and southeasterly back-azimuths (119 ~ 207 o , average 163 o) at station JJB. This may be due to a gradual velocity increase at Moho or heterogeneity within the crust. The v s models derived by inversion of receiver functions indicate a distinct low velocity layer (v s ≤ 3.5 km/s; LVL) within the crust and a gradual increase in v s in the depth interval of 30 to 40 km. Within the radius of 18 km beneath station JJB, the LVL occurs at depths of 14 ~ 26 km and the 'Moho' (v s ≥ 4.3 km/s) is at 34 km depth. Ten kilometers to the west, within the radius of 16 km beneath station JJU, both the LVL and the Moho are significantly shallower, at depths of 14 to 24 km and 30 km, respectively. H-κ analyses for stations JJU and JJB yield estimated crustal thickness of 29 and 33 km and v p /v s ratios of 1.64 and 1.75, respectively. The lesser v p /v s ratio was derived for rocks nearest to the peak of the volcano.

To estimate the S-wave velocity structure beneath the KS31 broad-band station in Wonju, Korea, we used Hκ stacking and joint inversion of receiver functions and surface-wave dispersion curves derived from 297 teleseismic events (Mw > 5.5) recorded during the period between 2002 and 2009. We thereby determined that the average depth to a nearly flat Moho is 32.4 ± 0.5 km within tens of kilometer radius of the seismic station. For the crust at this location, we estimate an average shear-wave velocity of 3.69 km/s and a ratio of P-to S-wave velocities, V P /V S , of 1.72 ± 0.04, as is typical for continental crust. A negative phase in the receiver functions at 1 s indicates the presence of a shearwave low velocity layer in a depth interval of 10 to 18 km in the upper crust beneath the KS31 station.