*2.1.6 Station 9*

Located on the eastern portion of the island, and this station corresponds to basalt without chemical alteration. Notice the low reflectance values (**Figure 13**), indicating the strong absorption of this rock. The larger reflectance noted in previous basalt samples in the 500–600 nm range is also present here, although somewhat subdued by the strong absorption. The rapid variations in the NIR range show large amplitudes in the three records.

#### *2.1.7 Station 10-2*

 This station corresponds to basalt not affected by chemical alteration. The records are shown in **Figure 14**, they show coherency among themselves, although Record 1 shows an anomalously high baseline reflectance, which we attribute to calibration effects. Record 1 shows rather high levels of reflectance with a well-defined plateau between 500 and 600 nm, as previously noted for other basalt samples. This feature is also present, although somewhat subdued, in Records 2 and 3. Between 350 and 500 nm, the latter shows a monotonous decrease in reflectivity that is not present in Record 1; they are attributed to the dispersion effect previously observed in other samples in this study. The NIR responses of the three records are quite similar and show various localized radiation absorptions.

#### *2.1.8 Summary*

Summarizing these radiometric results, we conclude that basalts present a distinct signature throughout the island, showing low reflectance, usually below 20%, that is distorted in some stations by alterations and/or the influence of disperse radiation. The calibration procedure performed prior to each measurement, and

#### **Figure 13.**

*Station 9 is located on the eastern portion of the island where unaltered basalts are clearly exposed. This station and Station 1 showed the lowest reflectance values in the island.* 

**Figure 14.** 

*Radiometric signatures of basalt at Station 10-2. These basalts did not present signs of chemical alteration. The baselines show larger values than those previously observed in basalt.* 

 the angle of measurement are most likely responsible for the baseline variations between measurements. Without considering the NIR band, we can establish a plateau reflectance response in the 500–600 nm bandwidth followed by a flat region between 650 and 900 nm, as the characteristics of the basalt response in this group of measurements (**Figures 4, 6, 7**, and **14**).
