The site B transmitter hub was located on the south rim of Pu`u `O`o cone and within 30 m of the edge. During this interval there were nearly as many different remote camera site configurations as there were new radial vents around the Pu`u `O`o cone (table 5). Figure 3 illustrates the three principle remote camera sites and camera perspectives that were intermittently occupied throughout the entire site B time interval.
On May 7, a camera on was placed on the south flank of the cone, 100 m from the transmitter hub. Site B1a (using the Canon camera) was pointed southward to view an area of near-vent perched lava ponds. From May 12 through May 15 this site was co-occupied by the Cohu wide-angle camera (Site B1b). On May 15, site B2, with the Canon camera, was positioned on the rim of the cone to view activity in the western side of the crater; it remained there until August 22. The Cohu stayed at the south flank site until July 1, when it was replaced by the Panasonic camera (site B1c). At this time, the Cohu wide-angle unit was re-staged at site B3, aimed northeastward into Pu`u `O`o from the south rim. This three camera configuration remained in place until August 6th ,when the Cohu camera at site B3 was overheated by lava rising to within a few meters of the camera site. After that time and until August 22, only sites B1c (south flank, looking south) and B2 (south rim, looking west) remained operational. Of the B1, B2, and B3 sites shown in Figure 3, all three were simultaneously occupied from July 1 through August 6. Sites B1 and B2 were working in tandem from May 15 to August 22. At this time the site B rim cameras and transmitter hub were at risk to lava flow inundation, and the RVTS-1 was returned to a safer environment on the north rim of Pu`u `O`o.
Figure 5 depicts the B1 remote camera site and sample images transmitted from this site between May 7 and August 22. The site B1 image archives record juvenile stages of perched-pond/lava-shield development near the Pu`u `O`o flank vents and the building of the Episode 55 South Shield. This record also provides distant glimpses of southeastward-moving flows that repeatedly threatened the Royal Gardens Subdivision during this interval. These flows could be traced by sparse glowing pixels in night-time images or as distant day-time smoke plumes from burning forest. This demonstrates the utility of the RVTS-1 as a real-time lava flow hazard mitigation tool.
Figure 5: Remote Camera Site B1 and Sample Images (May 7 - August 22, 1997)
The site B2 crater-vent and Site B3 wide-angle crater-pond perspectives are seen in figure 6 along with images transmitted from these sites between May 15 and August 22. The site B2 andB3 image database contains a record of several eruptive pauses along with rapid changes of eruptive vigor of the crater vent. This video record has captured the episodic drama of pond filling, overflowing, and draining. Comparison of real-time video records of South Shield and Pu`u `O`o activity demonstrate a synchronized interplay of eruptive venting within and around Pu`u `O`o. Observations gathered at the remote transmitter site B have provided important clues to the unknown physical character of a shallow plumbing system beneath Pu`u `O`o. This information is useful for forecasting vent behavior and demonstrates the usefulness of the HVO/RVTS-1 as an interpretive tool.
Figure 6: Remote Camera Site B2 and B3 and Sample Images (May 7 - August 22, 1997)
Site C is on the north rim of Pu`u `O`o with the cannon camera (site C2) pointed west toward the crater vent and the Panasonic (site C3) presenting a wide southern overview of the crater rim and floor. Activity in the cone has been continuous throughout this interval, and a video record of steady-state crater-vent effusion and intra-crater flow is marked by repeated surges in crater vent activity, pond filling, draining, and one crater overflow event on the east and west sides of the cone. Ebbs and surges in crater-vent activity are broadly correlated with periods of variable flux within the Episode 55 lava tube transport system from the flank vents. Figure 7 shows the site C2 and C3 camera installations and a selection of images from this record. The growing image database from Site C has documented a gradual change in crater-vent morphology from spatter cone to a perched lava pond, as well as the repeated formation and collapse of circumferential crater ledges.
Figure 7: Remote Camera Site C2 and C3 and Sample Images (August 22 - September 30, 1997)
HVO/RVTS-1 provides a clear demonstration of the value of real-time video telemetry in monitoring eruption activity. The image database provides a means for direct correlation of vent activity with real-time parameters of seismic tremor and deformation and also with subtle changes in the chemistry of erupted lava. While no major eruption or earthquake crisis has occurred during this interval, this system is staged to provide a direct means for evaluating the effects of any such crisis on eruptive activity at the vent itself.
This prototype remote video telemetry system is somewhat rudimentary in design and construction. It can be maintained "as is"at a relatively low cost and significantly improved with moderate capital investment. A few recommendations for improvement of the system are enumerated below.
1. An obvious and necessary improvement to the present system is a removable media storage drive at the receiver hub. For this purpose, a high capacity, high speed optical drive would provide the best means for image database storage and retrieval.
2. All components at the transmitter hub are presently "direct wired" through their respective enclosures. In order to improve serviceability and durability all equipment enclosures should be wired with external connector terminals. Such a modular design for remote-site equipment packages would greatly improve the portability of system components for servicing and re-deployment.
3. Up to the present time, all camera sites are restricted to stationary viewpoints. The versatility of the system would be greatly improved with the installation of one or more camera sites equipped with full remote control of camera Pan-Tilt-Zoom (PTZ). The design options for PTZ capability are presently being explored.
4. There are no replacements available for critical system components. It would be prudent to acquire equipment for complete transmitter-, and repeater-site backup. In addition to providing emergency replacement parts, duplicate transmitter and repeater sites could be deployed to document different perspectives around the vent area; lava flows far from the vent or littoral activity at the coastal entries. The existing receiver hub is capable of receiving an additional transmitter site, if modified with a special serial interface card.
Furukawa, B.T., Murray, T.L. and McGee, K.A., 1992, Video surveillance of active volcanoes using slow-scan television, in Ewert, J.W. and Swanson, D.A., eds., Monitoring Volcanoes: Techniques and Starategies Used by the Staff of the Cascades Volcano Observatory, 1980-1990: U.S. Geological Survey Bulletin 1966, p.189-194.
Miller, C.D. and Hobblitt, R.P., 1981, Volcano Monitoring by closed-circuit television, in Lipman, P.W. and Mullineaux, D.R., eds., The 1980 Eruptions of Mount. St. Helens, Washington: U.S. Geological Survey Professional Paper 1250, p.335-341.
FB Engineering (Hilo, HI), newly authorized local dealer of Hyperscan security systems, is credited for identifying and bench-testing the Hyperscan system for use with FreeWaveTM transceiver technology, while under contract to do so. The deployment and operation of the video telemetry array was accomplished with expert guidance from Mike Lisowski (USGS). Jeff Sutton (USGS) provided advice on instrument enclosures. Jim Kauahikaua, Christina Heliker, Dave Sherrod (USGS) and David Okita (Volcano Heli-tours) helped with setup, maintenance and rescue chores that have kept the video feed alive. Special appreciation is extended to Jim Kauahikaua for his input at both ends of the system. Arnold Okamura, Don Swanson (USGS) and Dave Clague (formerly USGS) are thanked for their support in making real-time video monitoring a reality at HVO. Asta Miklius (USGS) provided a helpful review of this report. Pauline Fukunaga (USGS) prepared this manuscript for web page publication.