**3. Materials and methods**

#### **3.1 Field mapping**

Reconnaissance visits were carried out to past volcanic eruption sites where a careful and systematic mapping of each of the volcanoes visited were carried out so as to determine its nature, size and composition. Other information acquired was their physical surface weathering features, morphology, outcrop patterns and the extent of vegetation cover.

#### **3.2 Petrographic and geochemical studies**

Rock samples were collected for petrography, geochemistry and geochronology. Both petrographic and geochemical studies were done in the Department of Geology, University of Jos, Nigeria. 40Ar-39Ar dating on the basalts was done in

Netherlands, Geological Survey Laboratory. For quality control, a duplicate geochemical analysis on the same basaltic rocks was carried out at the University of Cardiff, Wales using the Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES).

**S. No.**

**Name/ locality**

*Is a Volcanic Eruption Possible in Nigeria? DOI: http://dx.doi.org/10.5772/intechopen.84253*

4 Miango volcano I

5 Miango volcano II

6 Kassa volcanoes

7 Sha 1 N09° 10<sup>0</sup>

8 Sha 2 N09°10<sup>0</sup>

9 Passakai N09° 10<sup>0</sup>

12 Kerang I N09° 20<sup>0</sup>

13 Kerang II N09° 20<sup>0</sup>

10 Wushik (Lakas) volcano

11 Kogul (Nyeis) volcano

14 Kerang III volcano (Swan junction)

15 Kerang IV

**9**

**Coordinates Estimated**

N09° 51<sup>0</sup> .365″; E008° 43<sup>0</sup> .961″

N09 51. 000<sup>0</sup> ; E008 <sup>44</sup>″. 191<sup>0</sup>

Highest Peak: N09° 36<sup>0</sup> .119″; E008° 53<sup>0</sup> .521″

. <sup>543</sup>″;E008° 47<sup>0</sup> . 955″;

. <sup>846</sup>″;E008° 48<sup>0</sup> . 05″;

. <sup>543</sup>″;E008° 47<sup>0</sup> . 955″

N09° 24<sup>0</sup> <sup>165</sup>″; E009° <sup>10</sup><sup>0</sup> <sup>554</sup>″

N09° 22<sup>0</sup> <sup>573</sup>″;E009° <sup>11</sup><sup>0</sup> <sup>068</sup>″

<sup>286</sup>″;E009° <sup>11</sup><sup>0</sup> <sup>643</sup>″;

<sup>392</sup>″;E009° <sup>11</sup><sup>0</sup> <sup>502</sup>″;

N09° 20<sup>0</sup> <sup>306</sup>″;E009° <sup>10</sup><sup>0</sup> <sup>561</sup>″

N09° 11<sup>0</sup> <sup>283</sup>″;E008° <sup>12</sup><sup>0</sup> <sup>547</sup>″

I to IV put together 200,000

> Cinder Cone

Cluster (with 2 craters)

**population of people at risk**

For 1 & 2 250,000

**Type of volcano**

1 Bum 200,000 Cone Basaltic 2 Jal 150,000 Cone Basaltic 3 Kwakwi 250,000 Cone Basaltic

100,000 Cluster (6

overlapping volcanoes)

**Diameter of crater**

**Elevation (ASL)**

Cone 350 m 1297 m Scoraceous

Cone 650 m 1303 m ''

Average 1342 m

Average 300 m

20,000 Dome 200 m 1310 m Pyroclastics

10,000 Dome 200 m 1294 m Weathered

10,000 Dome 300 m 1375 m Lateritized

10,500 Cone 250 m 1300 m Scoria/

80,000 Cone 250 m 1250 m Scoria/

Cone 600 m 1400 m Scoria/basaltic

Cone 1000 m 1486 m Scoria/

1000 m 1450 m Scoria/basaltic

1.5 km 1372 m Pulverised

**Materials deposited**

basalt/ pyoclastics

Olivine basalt, scoria, tuff, breccia/volcanic bomb

(granite fragments/lava)

basaltic materials capped by iron concretions

pyroclastics

pyroclastics

rocks with large phenocrysts of olivine, garnet and pyroxene

rocks with large phenocrysts of olivine, garnet and pyroxene

pyroclastics

basement and lava

## **3.3 Hydrogeochemical monitoring study**

A constant monitoring of the Pidong Crater Lake through continuous water sampling 24–36 calendar months was done. The following physical parameters were recorded in the field using MT 806/pH/EC/TDS/Temp portable meter (pH, Temperature, Electrical Conductivity (EC), Total Dissolved Solids (TDS)). The water samples were collected in 100 ml polyethylene plastic bottles for cations and anion analysis. The sample for cations analysis was acidified with 0.1 M Nitric acid to prevent precipitating and bacterial growth. The following cations: Mg, Ca, Na, K, Cr, Ni, Co, Sc, V, Cu, Pb, Zn, Bi, Cd, Sn, W, Ma, As, Sb, Rb, Cs, Ba, Sr., Ga, Li, Ta, Nb, Hf, Zr, Y, Th, U, B, Fe & REEs were analyzed using ICP-MS method at Bureau Veritas Minerals Laboratory Limited, Canada while the anions: SO4, Cl, HCO3, NO3, F, Br and PO4 were carried out using colometry method at Maxxam Laboratory, Vancouver, Canada (subsidiary of Bureau Veritas Ltd).

#### **3.4 Isotope study**

Oxygen-18 (∂18O) and deuterium (∂<sup>2</sup> H), and (∂<sup>3</sup> H) and Carbon-14 (14C) isotopes of the Pidong Crater Lake, Bwonpe Volcanic Spring and rainfall were analyzed at Activation Laboratory Ontario, Canada using cavity Ring down spectroscopy (CRDS) model L11 02-1 California, USA with V-SMOW standards with typical standards deviation for 18O 0.1% and 1% for Tritium unit (TU).
