664 GEOLOGY OF SAMOA AND THE ERUPTIONS IN SAVAII, 



magnetic conditions. If that be not so, the solution of the 

 problem of seismic forecasting becomes simplified. Inasmuch as 

 sudden outbursts of prominences and faculse on the sun affect the 

 earth's magnetic conditions very quickly, and magnetic dis- 

 turbances may lead to earthquakes and eruptions in a region of 

 instability; and, further, as good seismograph records enable us 

 to judge, by the frequency of minor shocks, that earth-movements 

 are tending to take place under an area, it follows that, if we can 

 obtain sufficient knowledge of the sun to anticipate changes in 

 its atmosphere, we can forecast earthquakes. Solar physics is 

 now so well understood that seismic forecasting is within the 

 range of the practical. 



The eruption in Savaii, in 1902, took place during sunspot 

 minimum by the opening of a fissure. In my paper entitled 

 " Possible Relations between Sunspots and Volcanic and Seismic 

 Phenomena and Climate,"* I tried to show that earthquake 

 fissures would tend to form in years of sunspot minimum. 



The outpouring of lava from the 1902 volcano stopped quickly, 

 probably because of the height of the vent, 4500 feet above sea- 

 level, but pressure within the earth was not wholly relieved. In 

 the paper cited above I also mentioned that volcanoes situated on 

 fissure-lines in regions undergoing folding from rise of the 

 isogeotherms, may have their most violent outbursts in years of 

 sunspot maximum. That the Samoan-New Zealand volcanic 

 line marks such a region, I have shown probable. Hence, it is 

 not surprising to learn that new outbursts took place during the 

 maximum of 1905. Most of the violent eruptions on this line 

 have taken place at the end of sunspot maxima, e.g., Tarawera, 

 White Island and Niaufou, 1886; Falcon Island, 1885; Ruapehu, 

 1895; and many of the Hawaiian eruptions. 



8. Summary and Conclusions. 



In the foregoing notes I have attempted to give an account of 

 the area, composition, and appearance of the lava fields of Savaii; 



* Journ. Proc. Boy. Soc. N.S. Wales, Vol. xxxviii. 



