which of these is not a volcanic eruption hazard? course hero

What hazards do volcanoes create?

Most people are aware of the hazards that erupting volcanoes create, such as lava flows, hot, gaseous flows of volcanic blocks and ash, and mudflows.

Why are lava flows not a hazard?

As a result, lava flows are not much of a hazard because the lava does not flow very far - instead it piles up around the vent forming thick, stubby flows or domes. Nice work! You just studied 19 terms!

What happens to pyroclastic debris after a volcanic eruption?

The most explosive eruptions produce large eruption columns that carry pyroclastic debris to high altitudes, sometimes more than 10 km above Earth’s surface. When it returns to Earth, pyroclastic material may harden to produce a volcanic rock or it may remain unconsolidated.

Do volcanoes pose a threat to aviation?

Volcanic eruptions pose a serious threat to aviation, but one that can be mitigated through the combined efforts of earth and atmospheric scientists, the aviation industry, and air-traffic control centers.

What is the volcanic hazard to aviation?

The volcanic-ash hazard to aviation extends the volcanic threat far beyond the local area or region where a volcano is located. For example, the 1992 eruption of Mount Spurr in Alaska produced an ash cloud that was tracked on satellite images for three days and more than 3000 miles downwind of the volcano over Canada and the Great Lakes region.

How do volcanoes affect aviation?

Volcanoes threaten aviation safety when magma erupts explosively to form clouds of small jagged pieces of rocks, minerals, and volcanic glass the size of sand and silt that rises miles above the earth’s surface and is spread by winds aloft over long distances across flight paths of jet aircraft. Unlike the soft fluffy material created by burning wood, leaves, or paper, “volcanic ash” particles are angular, abrasive fragments having the hardness of a pocket-knife blade. Upon impact with an aircraft traveling several miles per minute, ash particles abrade the windscreen, fuselage, and fan blades in the turbine engines. In addition to the problem of abrasion, the melting temperature of the glassy rock material that comprises ash is lower than the operating temperatures of jet engines. Consequently, ingested ash particles can melt in hot sections of aircraft engines and then fuse onto critical components in cooler parts of the engine. An aircraft encounter with ash can result in loss of visibility, and failure of critical navigational and flight systems, and can immediately and severely degrade engine performance, resulting in engine flame out and total loss of thrust power.

How long did Anatahan volcano last?

In 2005, the volcano erupted to over 40,000 feet numerous times and expelled several million cubic yards of ash during a nearly continuous eruptive episode that lasted eight months. After the largest ash eruption, USGS provided forecasts of ash deposition on Saipan to the local government there. USGS also supports AFWA’s mission of providing volcanic-ash advisories and situational awareness to DOD aviation. For example, USGS volcanologists furnished short-term forecasts of potential ash-plume heights to AFWA for use in planning and completing a critical training exercise in the Marianas region by the USS Nimitz Carrier Strike Group.

How did the ash cloud affect the planes?

The potential for a disastrous outcome of an ash/aircraft encounter has been illustrated by three dramatic encounters. The first occurred in 1982 when a Boeing 747 – at night over water with 240 passengers – flew into an ash cloud about 100 miles downwind from Galunggung volcano in Indonesia. The aircraft lost power in all 4 engines and descended 25,000 ft from an altitude of 37,000 ft above sea level. After 16 minutes of powerless descent, the crew was able to restart three engines and make a safe landing in Jakarta. A few weeks later, a second Boeing 747 with 230 passengers encountered an ash cloud from another eruption of the same volcano. The aircraft lost power to 3 engines and descended nearly 8000 ft before restarting one engine and making a nighttime emergency landing on two engines. In both cases, the aircraft suffered extensive damage. Fortunately, a greater human tragedy was averted.

Why is the USGS monitoring volcanoes?

As the USGS has increasingly recognized that volcano monitoring is needed to protect against aviation hazards as well as the more well-known ground hazards , we have adjusted our monitoring program accordingly. For example, although the ground population is sparse in the volcanically active Aleutian Islands of Alaska, the risk to aviation is high. More than 200 flights carry roughly 25,000 people over Northern Pacific air routes on a daily basis. Since 1996, with funding support from FAA, AVO has undertaken to expand its monitoring beyond the few volcanoes that threaten communities around Cook Inlet in the south central portion of the state. Over the past decade, AVO has systematically expanded its seismic monitoring into the Aleutian chain, from 4 instrumented volcanoes in 1996 to 28 at the end of this past summer’s field work. This increase in real-time monitoring capability is an amazing accomplishment of both planning and execution on the part of AVO, a partnership between USGS, the University of Alaska Fairbanks, and the State of Alaska.

What is ash avoidance?

Ash avoidance is not a simple matter – it requires the coordinated efforts of volcanologists, meteorologists, air-traffic control centers, dispatchers, and pilots. It involves elements of: ground-based volcano monitoring, satellite-based detection of ash clouds, modeling cloud movements in the atmosphere, and specific communication protocols among the diverse parties responding to the hazard.

How can we improve our understanding of volcanoes?

Research is also a critical component of mitigation. To improve our forecasting abilities , we need to gain a much better fundamental understanding of eruption process es. Research and experience in the 25 years since the 1980 eruption of Mount St. Helens has brought volcanology to a point where, with adequate monitoring systems in place, the timing of volcanic eruptions can be forecast with some confidence hours to days in advance. The next major scientific goal for volcanology is to accurately forecast the size and duration of eruptions, which bears directly on hazards issues confronted by enroute aircraft and people on the ground. For instance, being able to forecast that an eruption will be small and unlikely to erupt ash to altitudes above 15,000 feet versus one that sends ash to 50,000 feet will have major impact on response by the aviation community. Another aspect is the ability to identify when an eruption is over, not just temporarily paused. This is quite a complex problem. Such information is valuable to airports, for example, because it tells them when they can start cleaning up from ashfall and hasten the return to normal operation.

Course reviews

This free course, Volcanic hazards, discusses the various hazards posed by different types of volcanic eruption, illustrated by examples from recent eruptions. The discussion is focused around reading Chapter 5 of Teach yourself volcanoes, earthquakes and tsunamis by OU volcanologist David Rothery.

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