Down Under in Savai’i
This is part of a series of illustrated articles taken from a report by geologist Tuapou Warren Jopling. Tuapou takes tour groups on Savaii and his knowledge is legendary.
1. Tafua - Savai'i Volcano
Visitors nearing Savai'i by ferry will see on the port (left) side an irregularly shaped hill rising above the treeline. It is not a particularly impressive sight and most would be surprised to hear that this is the largest of Savai'i's 450 volcanic cones. It was also the source of an enormous eruption during early Polynesian times and is now a wonderful eco-tourism attraction.
Tafua-Savai'i started life less than 2000 years ago and is Savai’i’s only volcano located on a shoreline. The cone is elongate in a WNW-ESE direction, and with a 130 m high central ridge separating two craters, east and west. A crater to most visitors means a deep, wide depression surrounded by vertical or sloping walls. The western crater fulfils this description but not the eastern where the entire northern wall has collapsed leaving a flat crater floor planted with village food crops.
Before climbing to the western crater a word about Tafua-Savai'i's eruptive history will explain the two very different rocktypes you will see. Molten magma on reaching surface is called lava. This fragments explosively with the seawater contained in the underlying surface rocks to produce tuff, a brown unstratified, granular rocktype containing fragments and blocks of the underlying black basalt. This initial violent phase of hydro-volcanism built high tuff rings around the two vents (eruptive centres). Molten lava pooled over the vents and surging caused spill over their rims to consolidate as thin basalt beds, gassy at top, dense at the base. The western lake drained (by lava tube?) leaving a 150m wide and 50m deep vertically walled crater.
Marine tuff can be seen in quarries on either side of Tafua-Tai village and along the plantation road that encircles the volcano. It is compact in outcrop but crumbles into sand under pressure and can be mixed with cement to make concrete flooring. It provides good soil for garden crops. You see thin basalt strata in the crater's wall and you can't help walking on loose slabs that have been dislodged by tree roots.
Enough geology! The purpose of your Tafua visit is to see some of Samoa's wildlife in a beautiful natural setting. An easy 10 minute walk up the volcano's north flank takes you to a low point of the western crater. With patience you will see large, diurnal Samoan flying foxes (Pteropus samoensis) circling the rainforest below you or gliding on air thermals way above. And the crater's forest is a haven for birdlife with frequent sightings of the smaller birds and Pacific pigeons and occasional sightings of colourful fruit pigeons. It's all very worthwhile but if you are energetic and want a truly exhilarating experience climb the track around the crater's eastern rim to the summit for the magnificent panorama over cone-studded southeastern Savai'i. The large circular cone you see on the skyline to the northwest is the Mt Mafane ash cone, taller than the cone you are presently standing on but slightly smaller in area. You will see this from many points along the south coast road.
The return walk to the top of the western crater takes about an hour. But why hurry back? Just relax and enjoy nature.
Your tour starts at Salelologa, Savai’i’s only commercial village and takes you clockwise visiting and discussing sites of interest.
1 The Tafua-Savai'i volcano. Tafua - Tai
2 The Afu A'au waterfall, Vailoa
3 A freshwater spring, Satupaitea
4 The Mu Pagoa waterfall and emerged shorelines, Puleia
5 An abandoned eucalypt forest, Gataivai
6 Sea arches and iron bound coastline, Taga
7 Alofa'aga Blowholes, Taga
8 Coral sand and beachrock, Satuiatua
9 Faulting, Fagafau
10 Moso's Footprint, Fagalele Bay
11 Canopy Walkway, Falealupo
12 The North Savai'i Fault, Sataua 13 The Mauga Afi eruption and Aopo Lava Field, Aopo
14 Lava tubes, Aopo, Letui, Paia
15 MataLeAlelo Spring, Mangroves, Safune
16 The Mauga Mu eruption - Discussion only
17 Mount Matavanu, Paia
18 Saleaula Lava Field, Saleaula
19 Mauga Crater
21 Mt To'iavea, Mt Tagotala
22 Puapua to Salelologa
23 Mt Silisili
24 Pulemelei Step Pyramid