# The Contribution of Near-Surface Geophysics for the Site Characterization of Seismological Stations
## 3 Application of the Geophysical Surveys and Processing Results
### Seismological Station at Thalero, Korinthia (THAL)  
Station _THAL_ (Figure 12) is located in the village of Thalero, near the southern coast of the eastern Gulf of Corinth. The station was installed on 12 June 2008 and currently employs a _Guralp CMG-DM24S6-EAM_ datalogger with a _CMG-40T/30s_ seismometer.  
The area where the station is located (Figure 12) comprises Upper Pliocene to Lower Pleistocene marine-brackish marks, part of the _Megalos Valtos_ formations (_Pl-Pt.m_). In places, recent torrent deposits (_Ht_) can be observed [72].  
Figure 11: SRT and MASW (**top**) and ERT (**bottom**) sections at the site of the seismological station _LOUT_.  
Figure 12: Location of the seismological station _THAL_ and the geophysical measurements along with the geology of the area.  
Station _THAL_ has a fairly flat HVSR curve (Figure 13), with multiple local maxima but without any prominent global one. In most cases, a dominant peak frequency is found at \(f\) = 1.4-1.5 Hz, with A = 1.7 \(\pm\) 0.4. A secondary peak can be observed in some cases at \(f\) = 2.3 Hz, with A = 1.6 \(\pm\) 0.3. Although the instrument is the same as that at station LOUT, there is no observed gradual drop of the amplification factor at f > 5.0 Hz, but a fairly constant base level at the amplification close to 1.5.  
The 2D seismic model (Figure 14) derived from the SRT technique revealed the existence of three seismic layers. The first layer has an average thickness of 3.0 m with a P-wave velocity value of \(V_{P1}\) = 550 m/s. The second layer's average thickness is estimated at 0.5 m with \(V_{P2}\) = 900 m/s. Finally, the third layer, which is considered the seismic bedrock, is present below the depth of 3.5 m and has a velocity value greater than 1300 m/s. Regarding the 1D, S-wave velocity distribution (Figure 14), the bedrock's shear-wave velocity was calculated as equal to 250 m/s. Furthermore, the S-wave velocity of the first 30.0 m was estimated at 300 m/s. According to the 2D distribution of the subsurface resistivity (Figure 14), two main geoelectrical layers were investigated. The first layer had an average thickness of 2.0 m and a resistivity value greater than 50.0 Ohm.m, whereas the second had a resistivity value below 50.0 Ohm.m, possibly affected by the subsurface moisture. At this point, we should mention that the geophysical line could not be executed closer to the station due to the inhabited character of the area and the stiff topography.  
Figure 13: Average HVSR curves (solid lines) determined for station _THAL_ on different days, from 60 s long windows selected after the application of STA/LTA anti-triggering on 6 h long records. Circles denote the global frequency on each curve, while diamond symbols mark the average of the frequency band denoting the range of peak frequencies of the HVSR lines from the individually selected windows (light/dark gray band in Figure 2b). Squares mark the prominent global and secondary peak frequencies recognized from the HVSR spectra, with error bars indicating the uncertainty of the amplification factor (Table A1).