EARTHQUAKES OF MAY 19 60 IN CHILE — SAINT-AMAND 349 



Krumm [5, 6] is erroneous. The 1960 eruption was probably from 

 the same fissures as the 1921 eruption. 



An eruption of Volcan Calbuco, certamly a part of this same 

 seismic crisis began on January 25, 1961, with the emission of steam 

 clouds and the production of earth tremors was reported by Erick 

 Klolin. On February 1 the first of a series of three lahars swept down 

 the slopes of the volcano and into Lake Llanquihue. Several small 

 streams of lava were emitted in late February and on March 10th a 

 large explosion occurred, accompanied by emission of ash and ejection 

 of large bombs. 



A new volcano was re]3orted by an Argentine helicopter pilot to be 

 erupting on the coast about 40 km. north of Valdivia near the town of 

 Curinanco (fig. 2). A crater several meters high was reported to 

 have formed and was apparently throwing rocks and ash into the 

 air. A submarine eruption was reported near this cite by bush pilots 

 several days after the earthquake, but the fact could not be confirmed. 

 There does not seem to have been volcanic activity in this area before. 

 None of these reports was confirmed, and it is suspected that what was 

 observed was a sand-blow, or mud volcano. 



Sand-blows, or mud volcanoes, were observed in many places and 

 were usually taken to be new volcanoes ; however, these are effects of 

 vibration and soil compaction on subterranean water and have noth- 

 ing to do with real volcanoes. 



FAULTING 



The careful ground and aerial search made by the field parties did 

 not disclose any clear-cut cases of faulting, that is to say, large displace- 

 ment of the land surface, such as have been observed in other earth- 

 quakes. In several places to the east of the Lakes, specifically on the 

 eastern side of Lago Calafquen (fig. 2), large cracks were found in 

 the ground that could have been produced either by faulting or by 

 landsliding. 



Weischet [7] reported a fault near Mehuin (fig. 2) that strikes 

 N. 6^° E. and shows li/^ to 3 cm. left lateral movement with about 

 3 cm. of sidewise separation. He reported a length of at least 300 m. 

 He shows a photograph and discusses what is obviously a type of 

 fault trace observed near Ensenada on Lake Llanquihue (fig. 3). 

 The general trace runs N. 13° E. for "hundreds of meters," and shows 

 no apparent lateral movement. Unfortunately, the trace is on alluvial 

 terrain. The same material is discussed by von Bauer [8]. 



In one of the astonishing accounts of the earthquake, a faultlike 

 trough some 30 km. long and 300 m. deep was reported to have formed 

 in the Lakes Region. A systematic search did not reveal this feature, 

 and it is probable that it was a misinterpretation of a more conven- 



