PART II— DYNAMICS OF THE SOLID EARTH 



Diversion and Modification 

 Through Technology 



Hilo, the second largest city in the 

 Hawaiian Islands, lies in the bottom 

 of a shallow, trough-like valley on the 

 east flank of Mauna Loa and Kilauea. 

 By chance, the most voluminous his- 

 toric flows have occurred on Mauna 

 Loa's west side and have, therefore, 

 flowed away from Hilo. In 1938 and 

 1942, however, lava flows erupted 

 from the east side of the peak and 

 proceeded downslope toward Hilo. 

 The U.S. Army Air Force, acting on 

 recommendations of geologists from 

 the HVO, bombed lava tubes in the 

 upper part of the 1942 flow, success- 

 fully diverting the flow of hot lava 

 from the interior of the tubes onto the 

 surface of the flow and possibly slow- 

 ing the forward advance of the flow's 

 leading edge some fifteen miles down 

 the hill. The flow did not reach Hilo. 

 The effectiveness of the bombing is a 

 matter of conjecture, however, since 

 termination of the extrusion of lava 

 from Mauna Loa occurred at about 

 the same time. 



While there have been no direct at- 

 tempts to alter the cycle of activity of 

 any volcano, a 1.2-megaton atomic 

 experiment conducted by the Atomic 

 Energy Commission on October 2, 

 1969, in Amchitka Island in the Aleu- 

 tians, may represent — though not by 

 design — the first such project. Kiska 

 Volcano, on Kiska Island, erupted on 

 September 12, about three weeks be- 

 fore the experiment was to be held 

 some 500 kilometers away. Had this 

 eruption occurred three or four weeks 

 later, a controversy about the possible 

 cause-and-effect relationships between 

 the blast and the eruption would un- 

 doubtedly have ensued. The experi- 

 ment on Amchitka was preceded by 

 considerable debate among seismolo- 

 gists about the possible effects on the 

 seismicity of that part of this tec- 

 tonically active island chain. Since 

 seismicity and volcanism are inti- 

 mately related on a worldwide basis, 

 the relevant areas in the Aleutians 

 should be carefully monitored for pos- 



sible alteration of the local volcanic 

 regimen. 



Potential Sources of Basic 

 Information 



It is clear that many disciplines will 

 contribute to progress in volcanology 

 — field geology, experimental and 

 observational petrology, geophysics, 

 geochemistry, fluid mechanics, and 

 others. Advances in our knowledge 

 of volcanic mechanisms can be ex- 

 pected from detailed observations, ex- 

 periments, and, eventually, theoretical 

 (mathematical) models. 



Field Observations — Any signifi- 

 cant advance in our knowledge and 

 understanding of volcanoes must be 

 observationally based. Like all geo- 

 logical processes, the number of pa- 

 rameters involved and the complexity 

 of the physical processes are very 

 great. Eruptions amount to large-scale 

 and uncontrolled natural experiments. 

 Meaningful quantitative data can only 

 be provided by systematic observa- 

 tions by prepared observers with ade- 

 quate instruments in the right place at 

 the right time. 



Any really basic, thorough under- 

 standing of volcano mechanisms, vol- 

 cano physics, and, eventually, erup- 

 tion prediction will follow detailed 

 observational work — both long-term 

 investigations of individual volcanoes 

 and ad hoc, short-term investigations 

 of volcanoes in a state of eruption. 

 The fruits of such observation can be 

 seen at Kilauea. Extended study by 

 the USGS has produced a detailed 

 geological, physical, and chemical de- 

 scription of this volcano. Detailed 

 knowledge of the behavior of Kilauea, 

 particularly prior to eruption, is 

 known, and reliable eruption predic- 

 tion by HVO has become routine. The 

 Hawaii experience underscores two 

 important points: (a) The ability to 

 predict the behavior of specific vol- 

 canoes is based on experience and 

 careful observation over a substantial 

 period of time, (b) Systematic collec- 



tion of several types of data (geo- 

 physical, geological, penological, 

 chemical) is required. 



Laboratory Experiments — There 

 are a number of laboratory experi- 

 ments that may yield useful informa- 

 tion: the chemical evolution of mag- 

 mas and mineralogical and chemical 

 evolution with time in relation to 

 eruption history are important param- 

 eters to establish. Petrologic and 

 chemical observation of volcanic prod- 

 ucts can be closely correlated to the 

 eruption history of observed (recent) 

 events or to carefully reconstructed 

 ones, yielding data about the evolu- 

 tion of magmas that culminate in 

 violent terminal activity. 



Laboratory investigation of physi- 

 cal properties of lava and magmatic 

 systems, especially volatile-bearing 

 ones, is needed. Little is known about 

 the physical characteristics of lavas 

 under dynamic conditions — for ex- 

 ample, expansion during rise in a vol- 

 cano from depth. The formation of 

 volcanic ash and catastrophic erup- 

 tions are associated with inhibited 

 vesiculation (bubbling) of lava during 

 rapid rise to the surface. These erup- 

 tions are the most destructive, and 

 they are not well understood. 



Experimental petrology (investiga- 

 tions of rock systems in controlled 

 situations in high-pressure vessels in 

 the laboratory) will yield data useful 

 in the quantitative reconstruction of 

 specific events as captured in rock 

 textures and in mineralogical asso- 

 ciations in volcanic rocks. By com- 

 parison of laboratory results with ob- 

 served relationships in volcanic rocks, 

 much can be inferred about the his- 

 tory of formation of specific volcanic 

 rocks that can never be directly ob- 

 served because the rocks occur too 

 deep within the volcano. 



Simulation Experiments — Some 

 progress could come from large-scale 

 simulation of certain volcanic proc- 

 esses, in much the same way as our 

 understanding of meteorite-impact 



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