VOLCANOLS 



physics was greatly aided by high- 

 yield atomic-explosion experiments. 

 It might be feasible to simulate cer- 

 tain aspects of volcanic eruptions on 

 a rather large scale. Such experiments 

 would yield useful information on the 

 interior ballistics problem (flow within 

 the interior of volcanoes) and also on 

 the exterior ballistics of volcanic 

 ejecta, especially ballistics of large 

 fragments. 



Small-scale model simulation of 

 volcanic processes is an exceedingly 

 difficult endeavor because of the 

 necessity to satisfy similitude require- 

 ments for both heat and mass trans- 

 fer. However, much has been learned 

 in a qualitative way about other geo- 

 logical processes — e.g., convection of 

 the earth's mantle and motion of 

 ocean currents — by such experi- 

 ments. The results, while semi- 

 quantitative, nonetheless can be quite 

 informative, especially when closely 

 tied to field observation. Model meth- 

 ods could profitably be applied (and 

 have been to a limited degree) to a 

 number of volcanic mechanisms, such 

 as the emplacement of lava and ash 

 flows. 



Mathematical Description — Vol- 

 canic processes are complex. The 

 eruption of volcanoes involves the 

 flow of a fluid system from a high- 

 pressure reservoir at depth to the sur- 

 face through a long rough pipe, or 

 conduit. In this process of fluid flow, 

 heat and momentum are exchanged 

 both within the system and with the 

 vent walls. As the erupting medium 

 rises, the confining pressure decreases 

 and a number of things result — ex- 

 solution and expansion of the vola- 

 tile phases (gas), and cooling due to 

 expansion. Near the surface, these 

 processes are rate-controlled rather 

 than simple equilibrium ones. 



Mathematical description of the 

 hydrodynamic and heat-transfer prob- 

 lems are rudimentary. There exists 

 abundant literature in engineering 

 and physics, however, which could 

 be applied readily to a number of vol- 



canic processes. For example, in the 

 last decade our knowledge of the be- 

 havior of complex multi-phase sys- 

 tems involving gas, solid, and liquid 

 phases has advanced because of their 

 importance in engineering practice 

 (e.g., to determine the flow in rocket 

 nozzles). General hydrodynamic 

 codes for the description of the de- 

 formation of material under shock 

 loading have been developed to de- 

 scribe target effects around explosions 

 and impacts, and these codes can be 

 modified to describe volcanic situa- 

 tions. Further, the flow in gas and oil 

 wells and reservoirs is probably simi- 

 lar to the flow in some volcanoes and 

 their reservoirs. Also, the interaction 

 of the high-velocity stream of gas and 

 fragments ejected by an erupting vol- 

 cano into the atmosphere is a special 

 case of the interaction of a jet with 

 fluid at rest. These problems appear 

 to be ripe and could develop very 

 swiftly. 



The science of petrology has pro- 

 gressed very rapidly in the last dec- 

 ade, to the extent that many quantita- 

 tive estimates can be made regarding 

 the temperatures and pressures of the 

 formation of certain minerals and 

 mineral assemblages found in vol- 

 canic rocks. These are very important 

 constraints on mathematical formula- 

 tion of the eruption problem. But the 

 greatest single impediment to the for- 

 mation of mathematical descriptions 

 of volcanoes in state of eruption is the 

 lack of systematic, quantitative field 

 data regarding eruption parameters 

 (mass flow rate, temperature, veloci- 

 ties and direction of fragments ejected, 

 the abundance and chemical composi- 

 tion of the gas phase, and petrog- 

 raphy and chemistry of the rocks 

 produced). 



State of Observational 

 Data and Tools 



Present data on active volcanoes 

 are quite incomplete, although the 

 means of acquisition of important in- 



formation are available. One reason 

 data are incomplete is that, prior to 

 modern jet transportation, it was 

 simply impossible for qualified sci- 

 entists to arrive at the scene in time 

 to gather the most interesting infor- 

 mation, which occurs in the first few 

 hours or days of activity of many vol- 

 canic events. 



For the past ten years, the Depart- 

 ment of Defense and National Aero- 

 nautics and Space Administration 

 have applied a powerful array of re- 

 mote-sensing and photographic tech- 

 niques to the investigation of some 

 volcanoes. The 1963 eruption of Surt- 

 sey, in Iceland, was studied, for ex- 

 ample. These methods hold great 

 promise and if applied to the study of 

 eruptions would produce a substantial 

 increase in the quantity of available 

 data as well as provide new kinds 

 of information. Even though means 

 exist for highly sophisticated and 

 complete investigations, however, the 

 number of eruptions that have been 

 thoroughly exploited is negligibly 

 small. 



The investigation of active vol- 

 canoes requires cooperation between 

 fairly small numbers (3 to 10) of well- 

 qualified professional observers, with 

 technical support (including commu- 

 nications, logistics, and transporta- 

 tion) to be provided at very short 

 notice. The Smithsonian Institution 

 has set up a facility to fill part of this 

 need: The Center for Short-Lived 

 Phenomena, in Cambridge, Massa- 

 chusetts. The center serves effectively 

 as an information source for scientists 

 covering a number of specialties, in- 

 cluding volcanology and geophysics. 

 The center notifies potentially inter- 

 ested scientists by telephone or wire 

 of events such as volcanic eruptions; 

 it then, on very short notice, organizes 

 teams to visit the sites, ideally within 

 24 hours. The function of the center 

 is to dispense information and to 

 organize logistics for adequately pre- 

 pared individuals with their own 

 funding. The number of such scien- 

 tists is well below the number re- 



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