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January 29, 1998


Volcano activity "weather" reports

Hawaiian volcanoes provide scientists a natural laboratory to study events that precede an eruption. The Hawaiian Volcano Observatory, in cooperation with other government agencies and universities, is installing new equipment, upgrading existing instruments, and improving data analysis to do comprehensive volcano monitoring in real time. Our goal is to track magma moving to the surface as it happens. Most of our efforts will be focused on Mauna Loa, the world's largest active volcano.

Volcanoes are built by repeated eruptions of hot, fluid rock (magma) from subsurface reservoirs. Changes in the magma supply to the reservoir and physical or chemical changes in the pooled magma increase reservoir pressure. The increased pressure sometimes results in lateral or upward migration of magma toward the surface through new cracks, or through the opening of old cracks. This forceful intrusion of magma triggers small earthquakes, which are often the first signs of unrest. It takes several hours to several days for magma to work its way to the surface.

Subtle changes in the shape of the volcano accompany the pressurization of the magma chamber and the intrusion of magma into the Earth's crust. This ground deformation is characterized by strains or tilts of 10 parts per million (about half an inch per mile) or greater and can easily be detected. The challenge is to deploy enough instruments so that we can record and identify an event as it is happening.

Computers will be continuously scanning the data to identify patterns of ground deformation. This process is analogous to that used to track the weather. Measurements are made at a large number of weather stations, and the data are integrated to produce the familiar weather maps. The volcanic deformation data can also be displayed with contour maps. Changes in magma pressure can be represented with charts similar to those for accumulated rainfall. Once unusual changes are detected, estimates of the location and amount of magma moving to the surface are calculated, and notifications are sent out.

Other data, such as earthquakes and gas emissions, could be incorporated into this volcano activity "weather" report and, someday, may be made available to the public. Maps of earthquake activity are already published weekly in newspapers in the San Francisco Bay Area and other seismically active metropolitan areas. Frequent publication or world-wide web access to volcano activity weather reports would result in a better-informed public. Although far-fetched now, one can imagine conversations like, "Did you notice the 10 parts per million strain event on Kilauea last week?"

The volcanoes of Hawaii are among the most studied in the world. Work over the next several years at the Hawaiian Volcano Observatory will make them the best monitored volcanoes in the world. Crisis response agencies, such as Civil Defense, will be better informed about what is happening and when it is occurring. Hawaii residents, as well as volcanologists, will gain a greater understanding of how volcanoes work.


Eruption and Earthquake Update, 29 January

Except for a brief pause on January 26, there was constant effusion of lava from the vent within Pu`u `O`o. Numerous breakouts from the tube system, mainly in the coastal plain area, produced surface flows. Lava from the tube system and the surface flows enter the ocean at two locations - Waha`ula and Kamokuna. The public is reminded that the ocean entry areas are extremely hazardous, with explosions accompanying frequent collapses of the lava delta. The steam cloud is highly acidic and laced with glass particles.


More than 15 earthquakes were felt by campers at the Namakani Paio campground in Hawaii Volcanoes National Park during the evening of January 27. The swarm of earthquakes originated about 3 km (1.8 mi) west of the summit of Kilauea Volcano along the Kaoiki fault zone from a depth of 4 km (2.4 mi). The largest earthquake at 8:01 p.m. had a magnitude of 4.4 and was felt in Hilo, Puna and Ka`u. Residents of the Volcano Golf Course subdivision and the Volcano community also felt some of the larger earthquakes of the swarm. A worker at HVO felt an aftershock on Wednesday morning at 8:25 a.m., and guests at KMC felt a foreshock at 5:29 p.m. on Tuesday afternoon. On January 25 at 8:25 a.m., an earthquake located 5 km (3 mi) northeast of Kilauea summit was reported felt by a resident of Glenwood. The earthquake had a magnitude of 3.6 and originated from a depth of 29.5 km (17.7 mi).


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