Here is a wonderful post by Richard at exploring our world.
How was the Grand Canyon created? « exploring our world
The Grand Canyon is a spectacular wonder of the West.
Tags: canyon, Grand Canyon
The western United States is home to 20 potentially active volcanoes. Just over half of these have shown activity in the past 2000 years.
The volcanoes of the western United States, especially those in the Cascades, are the result of subduction of oceanic plates beneath the edge of the North American Plate. The oceanic plates are made at mid-ocean ridges and are denser than the North American Plate. The North American Plate is made of continental crust and lithospheric mantle. Water from the oceanic plate helps to melt the hot asthenospheric mantle beneath the North American Plate. Magma rises through the plate to supply volcanoes.
Plate tectonics continues to drive our volcanoes. Eruptions of active volcanoes are imminent but very widespread.
In the bookstore: Volcanoes
On the web: USGS map
Image above: Mount Shasta 1984 (USGS)
Tags: USGS, volcanoes, western us volcanoes
Researchers hope epic journey will boost efforts to save the species. When you see the size of this thing you’ll see why she had to swim so far to find it’s food.
In the bookstore: Sea Turtles (books)
Tags: leatherneck turtle, sea turtle, turtle
Yellowstone National Park sits upon a giant caldera of a super volcano. Scientists have determined that it has erupted 3 times in the past.
The U.S. Geological Survey has released the following FAQ list concerning the prediction of the next eruption.
Is it true that the next caldera-forming eruption of Yellowstone is overdue?
No. First of all, one cannot present recurrence intervals based on only two values. It would be statistically meaningless. But for those who insist… let’s do the arithmetic. The three eruptions occurred 2.1 million, 1.3 million and 0.64 million years ago. The two intervals are thus 0.8 and 0.66 million years, averaging to a 0.73 million-year interval. Again, the last eruption was 0.64 million years ago, implying that we are still about 90,000 years away from the time when we might consider calling Yellowstone overdue for another caldera-forming eruption. Nevertheless, we cannot discount the possibility of another such eruption occurring some time in the future, given Yellowstone’s volcanic history and the continued presence of magma beneath the Yellowstone caldera.
When will Yellowstone erupt again?
We do not know. Future volcanic eruptions could occur within or near Yellowstone National Park for the simple reason that the area has a long volcanic history and because there is hot and molten rock, or magma, beneath the caldera now. Yellowstone is monitored for signs of volcanic activity by YVO scientists who detect earthquakes using seismographs and ground motion using GPS (Global Positioning System). YVO has not detected signs of activity that suggest an eruption is imminent.
The crust of North America continuously moves southwest over the Yellowstone hotspot as the Earth’s crust stretches above it, promoting the ascent of heat and molten rock. These processes produce basaltic magmas within the Earth’s mantle, which rise into the overlying crust and continue to heat the rocks beneath Yellowstone, maintaining and possibly adding to the rhyolite magma in the crust above.
Yellowstone’s 2-million-year history of volcanism, the copious amount of heat that still flows from the ground, the frequent earthquakes, and the repeated uplift and subsidence of the caldera floor also testify to the continuity of magmatic processes beneath Yellowstone and point to the possibility of future volcanism and earthquake activity.
What type of eruption will occur if Yellowstone erupts again?
Yellowstone’s volcanic and hydrothermal history suggests the potential for various kinds of eruptions in the future. The likelihood of a certain type of eruption occurring in the future can be judged by how often eruptions have occurred in the past.
- The most likely type of eruption would not be volcanic but, rather, hydrothermal. This type of small, but still explosive eruption can occur from shallow reservoirs of steam or hot water rather than molten rock. These reservoirs are the sources of Yellowstone’s famous geysers, hot springs, and fumaroles. Such explosions could blast out shallow craters more than a kilometer wide; as has occurred in the northern Yellowstone Lake Basin, including Mary Bay and nearby Turbid Lake and Indian Pond, and in western Yellowstone National Park north of Old Faithful. Each of these craters was produced by steam blasts within the past few thousand years.
- The most likely type of volcanic eruption at Yellowstone would produce lava flows of either rhyolite or basalt; rhyolitic lava eruptions could also include explosive phases that might produce significant volumes of volcanic ash and pumice. Such eruptions could range in size from smaller than the 1980 eruption of Mt. St. Helens through much larger than the 1991 Mount Pinatubo eruption.
- The least likely but worst-case volcanic eruption at Yellowstone would be another explosive caldera-forming eruption such as those that occurred 2.1 million, 1.3 million, and 640,000 years ago. However, the probability of such an eruption in any given century or millennium is exceedingly low- much lower than the smaller eruptions mentioned above.
When will the next large earthquake occur in Yellowstone?
Earthquakes cannot be predicted yet, but modern surveillance conducted with seismographs (instruments that measure earthquake locations and magnitudes) and Global Positioning System (GPS) instruments that measure slow ground movements help scientists understand the state of stress in the Earth’s crust that could trigger earthquakes as well as magma movement.
Could a large Yellowstone eruption significantly change weather patterns?
If another catastrophic caldera-forming Yellowstone eruption were to occur, it quite likely would alter global weather patterns and have enormous effects on human activity, especially agricultural production, for many years. In fact, the relatively small 1991 eruption of Mt. Pinatubo in the Philippines was shown to have temporarily, yet measurably, changed global temperatures. Scientists, however, at this time do not have the predictive ability to determine specific consequences or durations of possible global impacts from such large eruptions.
Can you release some of the pressure at Yellowstone by drilling into the volcano?
Scientists agree that drilling into a volcano would be of questionable usefulness. Notwithstanding the enormous expense and technological difficulties in drilling through hot, mushy rock, drilling is unlikely to have much effect. At near magmatic temperatures and pressures, any hole would rapidly become sealed by minerals crystallizing from the natural fluids that are present at those depths.
So, when will the next eruption occur? Nobody can predict. The threat, however, should not keep visitors away.
In the bookstore: Yellowstone Volcano (books)
On the web: Yellowstone Volcano Observatory
Snowfall over the past month has left many residents in northern Utah and southeastern Idaho feeling tired. Each week seems to bring at least 8 inches of fresh powder to the area. This weekend, however, looks to be nice but cold.
Lowes, Home Depot, and several local hardware stores have all sold out of snow blowers this season. “We can’t keep them in stock. People are sick of shoveling this winter,” an employee of Lowes said.
Logan has received approximately 30 inches this season with more reported on the mountain bench areas. Preston, Idaho has received as much as 36-44 inches in some areas.
The snow is welcome in this high desert region. Several years of low snowpack and drought conditions have hampered the area’s agriculture production.
