Entries Tagged 'Volcano Watch' ↓

Lava advances in “two steps forward, one step backward” style

Long-time Kilauea Volcano watchers know the drill when the supply of magma to the active vent on the volcano’s east rift zone is interrupted—abandonment of the “old” lava tube system, breakout of new surface flows, an evolving tube network, and eventually a new ocean entry.

This drama is unfolding again as many small `a`a and pahoehoe flows spread through what is left of the Royal Gardens subdivision and move a short distance across the coastal plain. The flows are providing sporadic, distant views of incandescent lava, glow, and burning vegetation from the Hawai`i County viewing area in Kalapana.

These flows are the consequence of a temporary decrease in magma supply to the active vent, beginning December 29 and lasting nearly 6 days. The decrease corresponded to a pronounced deflation of the summit and east rift zone area, followed by several days of only slight inflation as recorded by sensitive tiltmeters.

Scientists interpret deflation as an indicator of a relative decrease in magma supply and inflation as an increase in magma supply.

When the December 29 deflation event began, lava was pouring into the ocean at Waikupanaha, and more than 1,000 people per day were visiting the Hawai`i County lava viewing area. Within a few days, however, the entry shut off completely. Lava stopped entering the ocean by January 4, but some lava continued to move through the uppermost part of the tube system within about 3 km (2 miles) of the TEB vent.

The upper tube system lies within a complex series of rootless shields tens of meters (yards) tall that were built by thousands of overlapping small flows between November 2007 and February 2008. Near the lower end of these rootless shields, the original tube system became blocked as the Waikupanaha entry shut off, forcing lava to break out onto the surface at several locations between the shields and the top of Royal Gardens.

These flows are slowly creating a new but unstable tube system as the supply of magma to the vent continues to fluctuate. Seven deflation-inflation events have occurred since December 29.

During the inflation periods, new breakouts from the tube have generally formed longer flows that reached lower and lower elevations on the pali. Breakouts from the next inflation period often start lower than the previous breakout—evidence that the tube system was elongating and forming longer flows. The overall result of this pattern, as described by scientists, is a “two steps forward, one step back”-style of flow advancement and tube development.

Continued small fluctuations in magma supply as a consequence of small deflation-inflation cycles will likely promote growth of the new tube system all the way to the coast, west of the Waikupanaha entry. But a larger- or longer-than-usual deflation event may cause the young tube system to stagnate and trigger new breakouts above Royal Gardens in a sudden step backward.

Kilauea Activity Update

Surface flows have been active on the lower pali and coastal plain within the Royal Gardens subdivision. These flows have largely stayed close to the base of the pali but had extended halfway to the coast by Thursday morning. A deflation/inflation cycle, which started on Tuesday at Kilauea’s summit, caused these flows to slow down by mid-week. Surface flows in the same general area will likely be renewed when the volcano re-inflates.

At Kilauea’s summit, a spattering and roiling lava surface, deep within the collapse pit inset within the floor of Halema`uma`u Crater, was sporadically visible via Webcam. On several occasions, the lava surface rose slightly briefly covering the floor of the pit, but activity, for the most part, has remained fairly steady. Volcanic gas emissions remain elevated, resulting in high concentrations of sulfur dioxide downwind.

There were no felt earthquakes during the past week.

Visit the HVO Website for detailed Kilauea and Mauna Loa activity updates, recent volcano photos, recent earthquakes, and more; call (808) 967-8862 for a Kilauea summary; email questions to askHVO@usgs.gov.

Volcano Watch is a weekly article and activity update written by scientists at the U.S. Geological Survey’s Hawaiian Volcano Observatory.

Photo: Aerial view of Kilauea Volcano’s south flank shows new lava flows in Royal Gardens subdivision (center) and the coastal plain (bottom center). Blue smoke (center right) is from burning vegetation caused by active lava flows. The developing lava-tube system is marked by the linear alignment of fume left of the burning vegetation, extending to the horizon. U.S. Geological Survey photograph by Jim Kauahikaua, February 11, 2010.

A visit to Kilauea can bring a sense of awe and appreciation for the earth’s volcanoes. Over the past weeks, the east rift eruption has produced multiple ocean entries, and photogenic surface flows, which have touched off fiery infernos in the rare remaining kipuka (island of vegetation). The flows came uncomfortably close to the tourist trail that has carried tens of thousands of admiring visitors, and engulfed and destroyed a lone structure. Not to be outdone, the Halema`uma`u Overlook vent has offered glimpses of a rising and falling lava pond, as well as a landscape of molten, shifting holes opening into a deep cavity within the vent.

In contrast, living downwind of Kilauea’s copious gas emissions, or in the path of lava flows, can bring an exclamation of “auwe” (“oh dear!” or “Alas!”). Since the onset of summit activity in 2008, impacts from Kilauea have increased. Hawai`i County was declared a federal natural disaster area owing to agricultural losses, and air quality in downwind communities frequently exceeded federal and state standards.

While Kilauea does contribute modest amounts of gasses to the atmosphere, most impacts are local to Hawai`i. We might count ourselves lucky because growing evidence suggests that very large volcanic eruptions have extreme effects on the global environment. For example, massive volcanic activity around 60-70 million years ago occurred on the Deccan Plateau in what is now west-central India. This activity, which produced the Deccan Traps (from the Swedish word for stairs, Trappa, which refers to the feature’s step-like landscape), is one of the largest known eruptions to occur since the Earth’s initial formation.

There are distinct similarities between Kilauea and the Deccan Traps. While Kilauea is being created by the Hawai`i hot spot, the Deccan Traps were likely a product of the Reunion hot spot. The eruptive style of both can be characterized by multiple volcanic events separated by relatively short repose periods. They produce basaltic lava and have flow units with pahoehoe toes as the basic building block. In fact, scientists have studied Kilauea’s active volcanism as an analog for processes that would have created the Deccan Traps.

During the 0.5 million years or so since Kilauea first began growing from the floor of the ocean, 1,400 square kilometers (540 square miles) have been covered by lava, or about 1/7 the area of Hawai`i Island. The Deccan Traps currently cover 500,000 square kilometers (190,000 square miles), an area somewhat greater than that of California. During its peak, which likely lasted less than 1 million years, the eruption rate of the Deccan Traps was at least 15 times that of Kilauea’s current eruption rate, or at least 25 times that of Kilauea’s more modest lifetime eruption rate.

The timing of the Deccan Traps is intriguing, with the peak in activity occurring at around 65 million years ago. Movie buffs and dinosaur fans might recall the tagline for the 1993 movie Jurassic Park: “An Adventure 65 Million Years in the Making,” referring to the timing of the transition between the Cretaceous and Tertiary periods. Known as the K-T boundary, it was characterized by mass extinction of species, including the non-avian dinosaurs.

There is strong evidence that the impact of a large asteroid or comet contributed to this mass extinction due to the presence of enriched iridium in the fossil record at the K-T boundary. Iridium is an element that is much less abundant in the earth’s crust than in meteorites, and, thus, likely originated from space. The Chicxulub impact crater on the Yucatan Peninsula, Mexico, has been identified as a likely candidate for a K-T impact event.

However, growing evidence suggests that volcanic activity from the Deccan Traps was a significant contributor to the mass extinction event. Recent studies examining the fossil record were able to correlate an abrupt change at the K-T boundary in species of tiny sea creatures known as foraminifera, with the main eruptive pulse in the Deccan Traps.

Volcanoes great and small can affect life on earth, from contributing to the extinction of dinosaurs to impacting Kilauea’s neighbors.

Kilauea Activity Update

Lava continues to erupt from the TEB vent on Kilauea’s east rift zone and flow through tubes to the ocean at two locations—Waikupanaha and west Waikupanaha. Small surface flows have been sporadically active on the coastal plain for the last several weeks. In the past week, these surface flows were scattered mostly over a broad area more than 1 km to the west of the Hawai`i County lava viewing trail.

Glow above the vent at Kilauea’s summit has been visible at night from the Jaggar Museum. Incandescent openings, sometimes providing views of the lava surface, were visible on the floor of the vent cavity throughout the week by the Webcam perched on the rim of Halema`uma`u Crater. Volcanic gas emissions remain elevated, resulting in high concentrations of sulfur dioxide downwind.

One earthquake beneath Hawai`i Island was reported felt this past week. A magnitude-2.8 earthquake occurred at 6:04 a.m., H.s.t., on Sunday, November 15, 2009, and was located 3 km (5 miles) north of Paa`auilo at a depth of 11 km (7 miles).

Visit the HVO Website for detailed Kilauea and Mauna Loa activity updates, recent volcano photos, recent earthquakes, and more; call (808) 967-8862 for a Kilauea summary; email questions to askHVO@usgs.gov.

Volcano Watch is a weekly article and activity update written by scientists at the U.S. Geological Survey’s Hawaiian Volcano Observatory.

Charcoal (lower right), found under a lava flow, provides valuable clues to the past eruptive history of a volcano.

The key to unlocking the geologic secrets of a volcano’s future is its past. The further back we can peer into the past and delve into Pele’s secrets, the better we can understand eruptive behaviors of Hawai`i’s volcanoes. Examining data from long spans of time paints a clearer picture of a volcano’s eruptive history which, in turn, allows us to better appraise future volcanic activity.

But how can we be sure of a Hawaiian volcano’s eruptive history when written records began only 170 years ago? In terms of geologic time, 170 years is a mere blink of an eye, so we must use unwritten stories—those recorded by volcanoes themselves—to delve deeper into the past.

In 1980, geologists Jack Lockwood and Peter Lipman discovered that dating charcoal collected from beneath lava flows is a viable way to determine the ages of past eruptions. The technique, radiocarbon dating, was also used by archeologists to date cultural sites.

So, what’s unique about charcoal and how is it used to date volcanic events? Charcoal can be created when lava flows incinerate a forest. As lava buries vegetation, some of the plant material is reduced to ashes like those produced in your fireplace. Vegetation that is not completely burned up is preserved in the form of charcoal.

Carbon is commonplace in nature. In the atmosphere, the ratio of radioactive carbon-14 (C-14) to nonradioactive carbon-13 (C-13) and carbon-12 (C-12) is constant. During photosynthesis, a plant assimilates carbon (this particular ratio of C-14, C-13, and C-12) into the basic building blocks for leaves, branches, stem, and roots. As soon as the plant dies, however, the ratio begins to change as C-14 decays to C-13 or C-12.

The rate at which C-14 decays is well known, which enables scientists to use the ratio of radioactive to nonradioactive carbon to determine how much time has passed since the charcoal was created-a radiocarbon age. These ages are reported as years before present where “present” is 1950, the year when hydrogen bomb tests artificially produced C-14 and altered atmospheric carbon ratios.

Radiocarbon dating of charcoal can help determine the ages of lava flows up to about 50,000 years ago, which is the upper limit of this technique. Even with this limit, 50,000 years of eruptive history provides a much better indication of a volcano’s future behavior than 170 years of written records. The ages of older lava flows, like those on Kohala and most of Mauna Kea, must be determined using methods other than radiocarbon dating.

Collecting charcoal requires skill—and some luck—so we would like to solicit the help of Hawai`i island residents. We ask that you watch for charcoal, usually in the form of a dark black, sooty layer beneath lava flows, anytime you dig a septic system, excavate for cesspool, or grade a foundation.

If you find charcoal, the first thing to do is call HVO (808-967-7328) and let us collect a sample. If that’s not possible, you can collect it yourself. For the charcoal to be useful in revealing a volcano’s past, we need the following additional information with each sample.

We must know where you found the charcoal as accurately as possible. Note the location with GPS, mark it on a map, or include an address. In addition, take a photo or make a sketch of the charcoal in place, including the overlying lava flow. Put the charcoal in a sealed plastic bag, and collect a fist-sized piece of the overlying rock. Finally, call HVO for mailing or drop-off instructions or to arrange for pick-up.

The more we know about your charcoal sample, the more valuable it is and the greater help it provides. Proper documentation is the only difference between a valuable radiocarbon age and hibachi fuel.

By sleuthing out the eruptive history of Hawai`i’s active volcanoes, HVO can better understand and forecast future volcanic activity. Lend us hand by looking for charcoal to date our volcanoes.

Kilauea Activity Update

The breakout within the Royal Gardens subdivision remained active as of Thursday, June 11, but had diminished greatly compared to the previous week. A small breakout on the coastal plain active late last week was stagnant by early this week. No other active surface flows have been reported. The Waikupanaha and Kupapa`u ocean entries continue to produce prominent plumes as lava spills into the ocean.

At Kilauea’s summit, the vent within Halema`uma`u Crater continues to emit elevated amounts of volcanic gas, resulting in high concentrations of sulfur dioxide downwind. Bright glow from the vent was visible at night through the past week. Visits to the vent by HVO geologists have verified that lava remains at a fairly constant level about 100 meters (yards) below the floor of Halema`uma`u crater.

One earthquake beneath Hawai`i Island was reported felt this past week. A magnitude-2.2 earthquake occurred at 4:14 p.m., H.s.t, on Sunday, June 7, 2009, and was located 13 km (8 miles) west of Kawaihae at a depth of 10 km (6 miles).

Visit the HVO Web site for detailed Kilauea and Mauna Loa activity updates, recent volcano photos, recent earthquakes, and more; call (808) 967-8862 for a Kilauea activity summary; email questions to askHVO@usgs.gov. Volcano Watch is a weekly article and activity update written by scientists at the U.S. Geological Survey’s Hawaiian Volcano Observatory.

Lava in Kîlauea’s summit vent creates a nighttime glow that can be safely observed from the Jaggar Museum overlook in Hawai‘i Volcanoes National Park or on the HVO Webcam. Inset image shows the lava surface, which was moving from top center to lower left at the time it was taken.

The Hawaiian Volcano Observatory website was recently revamped to make access to our increasing number of Webcams easier for viewers and the HVO staff who post Webcam images. All HVO Webcams are now linked through a single menu.

The menu lists our five Webcams showing Moku`aweoweo, Mauna Loa summit caldera, the TEB vent and lava tube system on Kilauea’s east rift zone, Pu`u `O`o crater, and two views of the Halema`uma`u vent – one from HVO and another from the rim of Halema`uma`u crater immediately above the new vent.

Webcams allow us to make critical measurements with relatively little risk. The Webcams can work in rain, wind, very high concentrations of sulfur dioxide, and even moderate amounts of ash blasted from the vent. They can be in areas where access is restricted for safety reasons. Webcams can be where people should not.

Two of our Webcams have shown active lava in recent days. On Tuesday night, the TEB Webcam caught active flows near the top of the abandoned Royal Gardens subdivision. As an added treat, the Webcam also caught lights from a cruise ship passing the Kalapana shoreline in the late evening getting good views of the active flows and the Waikupanaha ocean entry.

The Webcams that chronicle developments below the floor of Halema`uma`u Crater have recorded lots of glow since early May. In fact, the recent glow has been the brightest since October 2008. The brightness of the glow is due to molten lava circulating in a narrow conduit about 100 m below the crater floor and about 180 m below the crater rim.

The Webcam located on the rim of Halema`uma`u was recently repositioned to look directly into the vent for views of the circulating lava when clear enough. The wispiness of the gas plume and the relative shallowness of the molten lava have allowed some good views recently. The vent is masked by sunlit fume during the day and is overexposed at night so the best times to look at Webcam views of lava are at dusk and dawn.

The unwavering Webcam views will allow us to better monitor the rise and fall of the lava within the vent. HVO geologists have also recorded video of the lava surface that shows some fascinating movements. The lava emerges from the right side of the Webcam view and flows left across the opening. The flowing lava surface looks chaotic with lots of splashing and bursting bubbles —activity that produces the tephra that is carried aloft by the hot, rising gas and deposited on the rim.

Two recent Volcano Watches have discussed reasons for lava circulation using a lava lamp analogy. Magma must be convecting with the conduit, like the “goo” in a lava lamp, bringing hot, bubble-rich lava to the surface while allowing cooler, bubble-poor lava to sink.

Looking at lava within the Halema`uma`u vent conduit is like watching a lava lamp from above through a hole in the top, all the goo colored orange, and blobs being gas bubbles that burst when they get to the top.

Views from the Halema`uma`u Webcam should allow us to test our ideas about what precedes brown plumes and explosive eruptions. Do rocks fall from vent walls into the molten circulating lava trigger a vigorous gas release which could carry even more spatter and rock dust out of the vent. Or are the brown plumes and more energetic explosive eruptions initiated by a big slug of gas coming up the conduit.

For safety reasons, Hawai`i Volcanoes National Park restricts access to the entire caldera including Crater Rim Drive from Jaggar Museum south to the Chain of Craters Road intersection. Thanks to the HVO Webcams, we can all see what’s happening from much safer vantage points.

Kilauea Activity Update

A deflation/inflation (DI) event at the summit of Kilauea last weekend disrupted the supply of lava through the tube system and caused the Waikupanaha and Kupapa`u ocean entries to shut down. Both entries had resumed by mid-week, accompanied by breakouts near the top of Royal Gardens subdivision and just inland from Kupapa`u.

At Kilauea’s summit, the vent within Halema`uma`u Crater continues to emit elevated amounts of sulfur dioxide gas, resulting in high concentrations of sulfur dioxide downwind. Vigorously upwelling lava within the vent below the crater floor produced bright glow at night, loud gas-rushing noises, and the emission of juvenile ash during the past week.

One earthquake beneath Hawai`i Island was reported felt this past week. A magnitude-3.4 earthquake occurred at 3:55 p.m., H.s.t, on Saturday, May 30, 2009, and was located 9 km (6 miles) southwest of Kilauea Summit at a depth of 26 km (16 miles).

Visit the HVO website for detailed Kilauea and Mauna Loa activity updates, recent volcano photos, recent earthquakes, and more; call (808) 967-8862 for a Kilauea activity summary; email questions to askHVO@usgs.gov. Volcano Watch is a weekly article and activity update written by scientists at the U.S. Geological Survey’s Hawaiian Volcano Observatory.

During the past two weeks, two noteworthy earthquakes struck Kilauea Volcano’s south flank. While the south flank is among the most seismically active areas in the U. S., the vast majority of earthquakes beneath it are too small to be of general interest. At the same time, each earthquake beneath the volcano represents a piece of a very complex puzzle that we continually watch and study.

The earthquakes on April 14 (magnitude 5.0) and April 21 (magnitude 4.2) occurred at depths of roughly 9 km (5.5 miles) below the Earth’s surface in regions adjacent to Kilauea’s east rift zone. These earthquakes gently punctuated the steady, southeastward motions of Kilauea’s south flank. They are noteworthy because they were widely felt across Hawai`i Island.

Parts of the active fault system responsible for the earthquakes are visible as the spectacular scarps that line Hawai`i’s southeast coast within Hawai`i Volcanoes National Park. A major part of the system—a fault representing the decollement, or detachment surface, between the ancient oceanic crust and the volcanic “pile” built up from repeated volcanic eruption and intrusion—becomes most apparent in larger earthquakes, as on April 14 or two of Hawai`i’s larger earthquakes in 1989 (magnitude 6.1) and 1975 (magnitude 7.2).

With capabilities afforded by continuous GPS monitoring, we measure considerable movement of Kilauea’s south flank that occurs as steady or stable motion. Large in a geophysical context, the movements occur at rates of several inches (centimeters) per year. At a conceptual level, it is reasonable to view the decollement as a through-going and somewhat uniform fault beneath the flank.

The south flank fault system is more complex, however, when seen from the perspective of earthquake distributions. There are some regions of the south flank that are surprisingly devoid of earthquake activity. Looking back through the Hawaiian Volcano Observatory’s record of seismicity, patterns of south flank earthquake hypocenters, or computed locations, also display a general level of clustering.

While they are all related to the decollement, April 2009’s two earthquakes and the 1989 and 1975 earthquakes each occurred in distinctly separate south flank clusters. The magnitude-5.0 earthquake on April 14 occurred in one of the south flank’s western earthquake clusters. The magnitude-4.2 earthquake on April 21 occurred about 10 km (6 miles) to the east of that cluster. The 1989 earthquake was located a few kilometers (miles) east of the April 21 hypocenter, and the 1975 earthquake was about 8 km (5 miles) east of the 1989 hypocenter.

Interestingly, between the two clusters containing the April 2009 earthquakes lies a section of the south flank decollement system that has produced thousands of small earthquakes, but not a single magnitude 4 or larger earthquake since 1970. In comparison, during that same time interval, the April 14 magnitude-5.0 cluster has produced 30 such earthquakes, and the April 21 magnitude-4.2 cluster has produced 45 such earthquakes.

The earthquake clustering reflects variation in fault properties and fault structure along the decollement. Variation of earthquake behaviors within and among different clusters reflects additional complexity associated with movement of the south flank. In addition to understanding the fault properties and structures, we are striving to learn more about the forces resulting from magma residing in the rift zones and the frictional resistance along the active faults.

Each new south flank earthquake, especially if large enough to be felt, reprises questions of Kilauea’s next possible magnitude-7 south flank earthquake. While we lack clear-cut answers to some of those questions, each earthquake compels us to look more closely and provides new information to fit into the Kilauea puzzle.

Activity update

The Waikupanaha and Kupapa`u ocean entries remain active, with small littoral explosions common at the Kupapa`u entry over the past week. Surface flows inland from Kupapa`u remain active along the eastern boundary of Hawai`i Volcanoes National Park.

At Kilauea’s summit, the vent within Halema`uma`u Crater continues to emit elevated amounts of sulfur dioxide gas, resulting in high concentrations of sulfur dioxide downwind. Variable glow and vent noises over the past week suggest that lava is still present at shallow levels below the floor of Halema`uma`u crater.

A magnitude-4.2 earthquake at 4:58 p.m. H.s.t. on Tuesday, April 21, was located beneath Kilauea’s south flank, about 44 km (27 miles) south of Hilo and at a depth of 9.2 km (5.7 miles). The earthquake caused no significant changes to Kilauea’s ongoing eruptions. More than 200 people reported feeling it.

Visit the HVO Web site for detailed Kilauea and Mauna Loa activity updates, recent volcano photos, recent earthquakes, and more; call (808) 967-8862 for a Kilauea summary; email questions to askHVO@usgs.gov.

Volcano Watch is a weekly article and activity update written by scientists at the U.S. Geological Survey’s Hawaiian Volcano Observatory.

The holiday season is once more upon us, with the solstice arriving at 2:04 a.m. Hawaiian Standard Time on Sunday, December 21, and Chanukah, Christmas, and Kwanza following soon afterward. Many cultures and traditions mark the season with celebrations that include good food, cheer, and especially, light, to help dispel the darkness of winter.

Kilauea also appears to be observing the seasonal holidays. At the beginning of December, it seemed that the summit vent might be getting into the swing of things by producing the photogenic red glow that was ubiquitous through much of the summer and early fall. For locals and visitors alike, an evening watching the mesmerizing show from the rim of the caldera was cause for celebration. But, since mid-October, the glow has been notably absent.

The promise of extra volcanic glow for the solstice abruptly ended on December 4, when the familiar white, fluffy plume went through several brief ash-rich phases and then changed into a wispy, translucent shadow of its former self. The vent temperature also went down an extra step from the reduced values observed throughout the fall; then on December 5, the promising glow disappeared

The activity at Kilauea’s summit continued to exhibit both subtle and obvious changes – perfectly timed with the Dutch observance of Sinterklaas, the celebration of the birthday of Saint Nicholas.

The dark, early morning hours of December 5 were heralded by loud booms, the sound of falling rock, and a thick, dirty plume which generated a notable dusting of ash. A flurry of small quakes occurred in the vicinity of Halema`uma`u, accompanied by very low frequency sounds and minor collapses of the vent rim. By December 6, a large slice of the vent rim had fallen in, and the vent diameter had increased to 98 meters (107 yards) –wide enough to house a football field.

Since that time, the summit activity has been characterized by small, and even smaller, ash and tephra falls. Much of it has likely been fragments crumbling from the older rock in the conduit wall and carried up in the escaping gas column, with only a very small amount of fresh, glassy spatter erupted. There may have been a tiny bit of glow observed, but it was subtle, at best. Vent sounds have been variable, ranging from solemn quiet to vigorous gas-jetting and tinkling rock-fall sounds.

Perhaps the most notable change that the casual Kilauea admirer would perceive is the wispy, languid plume that curls lazily from the vent. Indeed, the rate of SO2 gas release from the summit vent has dropped to about 20 percent of its maximum value since the vent opened in March, and about 40 percent of its average value for that time period. The reduction in summit SO2 emission rate may give the communities and farmers to the south and west in the Ka`u and Kona districts a welcome reprieve. Air-quality monitoring revealed that, since the onset of the summit eruption, the primary health standards for SO2 gas have been exceeded on 36 occasions in Pahala. Health standards for particle pollution have been exceeded 14 times in Pahala and 10 times in Kona. Prior to the onset of the summit activity, no exceedance of the health standards was recorded for either community.

Over the past week, residents in East Hawai`i would have been hard pressed to notice that summit SO2 emissions were a fraction of their typical amount. Kona wind conditions intermittently fumigated the communities adjacent to the National Park and along Highway 11 with substantial amounts of SO2 gas and acid particles, mainly from Pu`u `O`o but with some contribution from the summit. While summit emissions have declined markedly, the copious emissions from Pu`u `O`o continue. Currently they are about five times those at the summit. Although no health standards were exceeded at any of the East Hawai`i air quality monitoring stations in the past week, concentrations in the National Park exceeded 1 ppm, resulting in an “unhealthy” condition advisory.

Kilauea may be observing the holiday season with a stutter in the summit activity, but historically, long-lived summit eruptions typically waxed and waned. Even with a growing volcanology toolkit, it is difficult to know exactly what will follow this most recent shift in activity. Perhaps things will have changed again by the time Santa arrives — or even by the time you read this.

Activity Update

Kilauea Volcano continues to be active. A vent in Halema`uma`u Crater is erupting elevated amounts of sulfur dioxide gas and very small amounts of ash. Resulting high concentrations of sulfur dioxide in downwind air have closed the south part of Kilauea caldera and produced occasional air quality alerts in more distant areas, such as Pahala and communities adjacent to Hawai`i Volcanoes National Park, during kona wind periods. There have been several small ash-emission events from the vent, lasting only minutes, in the last week. In addition, a series of three deflation-inflation cycles was recorded at Kilauea’s summit in the past week. These cycles normally cause short-term fluctuations in lava supply to the flow field.

Pu`u `O`o continues to produce sulfur dioxide at even higher rates than the vent in Halema`uma`u Crater. Trade winds tend to pool these emissions along the West Hawai`i coast, while kona winds blow these emissions into communities to the north, such as Mountain View, Volcano, and Hilo. Lava erupting from the Thanksgiving Eve Breakout (TEB) vent at the eastern base of Pu`u `O`o continues to flow to the ocean at Waikupanaha through a well-established lava tube. Beakouts from the lava tube were active in the Royal Gardens subdivision and on the coastal plain in the past week. The flows on the coastal plain had reached 140 yards across the National Park boundary by last weekend but were stagnant when mapped on December 16. These flows have diminished over the past week, but may still be active near the base of the pali.

Be aware that active lava deltas can collapse at any time, potentially generating large explosions. This may be especially true during times of rapidly changing lava supply conditions. The Waikupanaha delta has collapsed many times over the last several months, with three of the collapses resulting in rock blasts that tossed television-sized rocks up onto the sea-cliff and threw fist-sized rocks more than 200 yards inland. Do not approach the ocean entry or venture onto the lava deltas. Even the intervening beaches are susceptible to large waves generated during delta collapse; avoid these beaches. In addition, steam plumes rising from ocean entries are highly acidic and laced with glass particles. Call Hawai`i County Civil Defense at 961-8093 for viewing hours.

Mauna Loa is not erupting. One earthquake was located beneath the summit this past week. Continuing extension between locations spanning the summit indicates slow inflation of the volcano, combined with slow eastward slippage of its east flank.

Two earthquakes beneath Hawai`i Island were reported felt within the past week. Both were located at a depth of 2 km (1 mile).beneath the Steaming Bluffs – Sulfur Bank area on the north rim of Kilauea caldera. A magnitude-3.1 earthquake occurred at 4:05 p.m., H.s.t., on Monday, December 15, 2008, and a magnitude-2.6 earthquake occurred at 4:53 p.m. on Wednesday, December 17.

Visit our Web site for daily Kilauea eruption updates, a summary of volcanic events over the past year, and nearly real-time Hawai`i earthquake information. Kilauea daily update summaries are also available by phone at (808) 967-8862. Questions can be emailed to askHVO@usgs.gov.

This article was written by scientists at the U.S. Geological Survey’s Hawaiian Volcano Observatory.

Royal Gardens subdivision was back in the news again this past week as a lava flow from the July 21 fissure advanced to within 300 m (985 ft) of the uppermost cross street. On the evening of January 8, a rootless shield near the fissure breached, releasing a flood of lava that formed a channelized `a`a flow. For the next five days, the flow advanced toward Royal Gardens until it stagnated late on January 13. As long as the rootless shields directly uphill of the subdivision remain active, this is likely to be a temporary reprieve for the two remaining residents.

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Despite the potential hazards, the ongoing eruption from Kilauea’s east rift zone is a remarkable and fascinating sight. It is startling to see a river of lava coursing between broad levee walls that tower above the surrounding land surface. What the casual observer may not know, however, is that this is a one-of-a-kind phenomenon. A perched lava channel has never been seen before. This makes it particularly difficult to forecast what might happen next.

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The rift zones of Hawaiian volcanoes are long strips 1-2 miles wide in which eruptions can occur. They radiate from the volcanic summits, where eruptions occur most frequently. Most Hawaiian volcanoes have at least two rift zones. Volcanologist�s interpretations of the workings of rift zones are based primarily on close observations of eruptions at Kilauea and Mauna Loa. Magma is believed to come up from depths of at least 60-80 km into a holding area, a magma reservoir, 3-5 km beneath the summit. This part of the process can be monitored with seismometers, tiltmeters, GPS receivers, and gas sensors.

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People who are fortunate enough to live in or visit Hawai`i, or even those who have seen the right television documentaries, know that the majestic presence of erupting volcanoes attests to their raw power. If we took Kilauea (our own backyard volcano) and collected the lava that it erupted, there would be enough material to fill the gas tanks of about 1,000 Sport Utility Vehicles (SUVs) in the time it took you to read this sentence. And though Kilauea is a medium-to-small-sized volcano, it has been discharging lava nearly continuously at this rate for the past 24 years.

Demonstrations like this one, or catastrophic eruptions like those of Mount St. Helens or Mount Pinatubo, understandably cause people to sometimes think that human-caused effects on the biosphere are small compared to volcanic ones. But, as the saying goes, “it ain�t necessarily so.”

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