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1
Mount Pinatubo is an active
stratovolcano located on the island of
Luzon in the
Philippines, at the intersection of the borders of the provinces of
Zambales,
Tarlac, and
Pampanga. Ancestral Pinatubo was a stratovolcano made of
andesite and
dacite. Before 1991, the mountain was inconspicuous and heavily
eroded. It was covered in dense
forest which supported a population of several thousand indigenous people, the
Aeta, who had fled to the mountains from the lowlands when the
Spanish conquered the Philippines in 1565. The volcano's eruption in June 1991, more than 490 years after the last known eruptive activity, produced the second largest terrestrial eruption of the 20th century. Successful predictions of the onset of the climactic eruption led to the evacuation of tens of thousands of people from the surrounding areas, saving many lives, but as the surrounding areas were severely damaged by
pyroclastic flows, ash deposits, and later,
lahars caused by rainwater remobilising earlier volcanic deposits, thousands of houses were destroyed. The effects of the eruption were felt worldwide. It ejected roughly 10 billion metric tons of magma, and 20 million tons of
SO2, bringing vast quantities of minerals and metals to the surface environment. It injected large amounts of
aerosols into the
stratosphere—more than any eruption since that of
Krakatoa in 1883. Over the following months, the aerosols formed a global layer of
sulfuric acid haze. Global temperatures dropped by about 0.5
°C (0.9
°F), and
ozone destruction increased substantially.
2
The
Chicxulub Crater is an ancient
impact crater buried underneath the
Yucatán Peninsula, with its center located near the town of
Chicxulub,
Yucatán,
Mexico. The crater is over 180 kilometers (110 mi) in diameter, making the feature one of the largest confirmed impact structures in the world; the
asteroid or
comet whose impact formed the crater was at least 10 km (6 mi) in diameter. The crater was named for the nearby town, as well as for the literal
Maya translation of the name: "tail of the
devil." The crater was discovered by Glen Penfield, a geophysicist who had been working in the Yucatán while looking for
oil during the late 1970s. The presence of
tektites,
shocked quartz and
gravity anomalies, as well as the age of the rocks and
isotope analysis, show that this impact structure dates from the late
Cretaceous Period, roughly 65
million years ago. The impact associated with the crater is
implicated in causing the extinction of the
dinosaurs as suggested by the
K–T boundary, although some critics disagree that the impact was the sole reason and also debate whether there was a single impact or whether the Chicxulub impactor was one of several that may have struck the Earth at around the same time. Recent evidence suggests that the impactor was a piece of a much larger asteroid which broke up in a collision more than 160 million years ago.
3
Hurricane Floyd was the sixth named storm, fourth
hurricane, and third major hurricane in the
1999 Atlantic hurricane season. Floyd triggered the second largest evacuation in US history (behind Hurricane Rita) when 2.6 million coastal residents of five states including Florida were ordered from their homes as Hurricane Floyd approached. The
Cape Verde-type hurricane formed off the coast of Africa and lasted from
September 7 to
September 19, peaking in strength as a very strong Category 4 hurricane — just short of the highest possible rating — on the
Saffir-Simpson Hurricane Scale. It was among the largest
Atlantic hurricanes of its strength ever recorded. Floyd struck
The Bahamas at peak strength, causing heavy damage. It then paralleled the
East Coast of the United States, causing massive evacuations and costly preparations. The storm weakened significantly, however, before making landfall in
North Carolina as a Category 2 hurricane, and caused further damage as it traveled up the
Mid-Atlantic region and into
New England. The hurricane produced torrential rainfall in eastern North Carolina, adding more rain to an area hit by
Hurricane Dennis just weeks earlier. The rains caused widespread flooding over a period of several weeks; nearly every river basin in the eastern part of the state exceeded 500-year flood levels. In total, Floyd was responsible for 57 fatalities and $4.5 billion ($5.7 billion in 2006
U.S. dollars) in damage, mostly in North Carolina.
4
The
Yellowstone fires of 1988 together formed the largest
wildfire in the recorded history of
Yellowstone National Park. Starting as many smaller individual fires, the flames spread quickly out of control with increasing winds and
drought and combined into one large
conflagration, which burned for several months. It was finally extinguished by moist weather in the late fall. A total of 793,880 acres (3,213 km²), or roughly 36 percent of the park was affected by the wildfires. Thousands of
firefighters fought the fires, assisted by dozens of
helicopters and
airplanes which were used for water and
fire retardant drops. At the peak of the effort, over 9,000 firefighters were assigned to the park. With fires raging throughout the
Greater Yellowstone Ecosystem and other areas in the western United States, the staffing levels of the
National Park Service and other land management agencies were inadequate to the situation. Over 4,000
U.S. Military personnel were soon assisting in fire suppression efforts. The fire fighting effort cost $120 million. No firefighters died while fighting the fires in Yellowstone, though there were two fire-related deaths outside the park. The Yellowstone fires of 1988 were unprecedented in the history of the National Park Service, and many questioned existing fire management policies.
Media accounts of mismanagement were often sensational and inaccurate, sometimes wrongly reporting that most of the park was being destroyed. While there were temporary declines in air quality during the fires, no adverse long-term health effects have been recorded in the ecosystem. Contrary to initial reports, few large mammals were killed by the fires, though there has been a reduction in the number of
moose which has yet to rebound. Losses to structures were minimized by concentrating fire fighting efforts near major visitor areas, keeping property damage down to $3 million.
5
Yellowstone National Park became the world's first
national park on
March 1,
1872. Located mostly in the
U.S. state of
Wyoming, the park extends into
Montana and
Idaho. The park is known for its
wildlife and
geothermal features, especially
Old Faithful Geyser, one of the most popular areas in the park.
Native Americans have lived in the Yellowstone region for at least 11,000 years. The region was bypassed during the
Lewis and Clark Expedition in the early 1800s. Aside from visits by
mountain men during the early to mid-1800s, organized exploration did not begin until the late 1860s. The
U.S. Army was commissioned to oversee the park just after its establishment. In 1917, administration of the park was transferred to the
National Park Service, which had been created the previous year. Hundreds of structures have been built and are protected for their architectural and historical significance, and researchers have examined more than 1,000 archaeological sites. Yellowstone National Park spans an area of 8,987
square kilometres (3,470
sq mi), comprising lakes, canyons, rivers and
mountain ranges.
Yellowstone Lake is the largest high-altitude lake in
North America and is centered over the
Yellowstone Caldera, the largest
supervolcano on the continent. The caldera is considered an active volcano; it has erupted with tremendous force several times in the last two million years. Half of the world's geothermal features are in Yellowstone, fueled by this ongoing volcanism.
Lava flows and rocks from volcanic eruptions cover most of the land area of Yellowstone. The park is the centerpiece of the
Greater Yellowstone Ecosystem, the largest remaining, nearly-intact ecosystem in the Earth's northern temperate zone.
6
Plate tectonics is a
theory of
geology that has been developed to explain the observed evidence for large scale motions of the
Earth's
lithosphere. The theory encompassed and superseded the older theory of
continental drift from the first half of the 20th century and the concept of
seafloor spreading developed during the 1960s. The outermost part of the Earth's interior is made up of two layers: above is the
lithosphere, comprising the
crust and the rigid uppermost part of the
mantle. Below the lithosphere lies the
asthenosphere. Although solid, the asthenosphere has relatively low
viscosity and
shear strength and can flow like a liquid on geological time scales. The deeper mantle below the asthenosphere is more rigid again. This is, however, not due to cooler temperatures but due to high pressure. The lithosphere is broken up into what are called
tectonic plates—in the case of Earth, there are seven major and many minor plates (
see list below). The lithospheric plates ride on the asthenosphere. These plates move in relation to one another at one of three types of plate boundaries:
convergent or collision boundaries,
divergent or spreading boundaries, and
transform boundaries.
Earthquakes,
volcanic activity,
mountain-building, and
oceanic trench formation occur along plate boundaries. The lateral movement of the plates is typically at speeds of 0.65 to 8.50 centimeters per year (the speed at which human nails grow).
7
Amchitka is a volcanic,
tectonically unstable island in the
Rat Islands group of the
Aleutian Islands in southwest
Alaska. It is about 68 kilometres (42 mi) long, and varies from 3 to 6 km (2–3.75 mi) in width. It has a maritime climate, with many storms, and mostly overcast skies. The island was populated for more than 2,500 years by the
Aleut people, but has had no permanent population since 1832. It was included in the
Alaska Purchase of 1867, and has since been part of the
United States. During
World War II, it was used as an airfield by US forces in the
Battle of the Aleutian Islands. Amchitka was selected by the
United States Atomic Energy Commission to be the site for underground
detonations of
nuclear weapons. Three such tests were carried out:
Long Shot, an 80
kiloton blast in 1965;
Milrow, a 1
megaton blast in 1969; and
Cannikin in 1971 — at "under 5 megatons", the largest
underground test ever conducted by the United States. The tests were highly controversial, with
environmental groups fearing that the
Cannikin explosion, in particular, would cause severe
earthquakes and
tsunamis. Amchitka is no longer used for nuclear testing, although it is monitored for the
leakage of radioactive materials.
8
The
climate of India comprises a wide range of weather conditions across a large geographic scale and varied topography, making generalisations difficult. Analysed according to the
Köppen system,
India hosts six major climatic subtypes, ranging from
desert in the west, to
alpine tundra and
glaciers in the north, to humid tropical regions supporting
rainforests in the southwest and the island territories. Many regions have starkly different
microclimates. The nation has four seasons: winter (January and February), summer (March to May), a
monsoon (rainy) season (June to September), and a post-monsoon period (October to December). India's unique
geography and
geology strongly influence its climate; this is particularly true of the
Himalayas in the north and the
Thar Desert in the northwest. The Himalayas act as a barrier to the frigid
katabatic winds flowing down from
Central Asia. Thus,
North India is kept warm or only mildly cold during winter; in summer, the same phenomenon makes India relatively hot. Although the
Tropic of Cancer—the boundary between the tropics and subtropics—passes through the middle of India, the whole country is considered to be tropical. As in much of the tropics, monsoonal and other weather conditions in India are unstable: major droughts, floods, cyclones and other natural disasters are sporadic, but have killed or displaced millions. India's long-term climatic stability is further threatened by
global warming. Climatic diversity in India makes the analysis of these issues complex.
9
The
Ediacara biota are ancient lifeforms of the
Ediacaran Period, which represent the earliest known complex
multicellular organisms. They appeared soon after the Earth thawed from the
Cryogenian period's
extensive glaciers, and largely disappeared soon before the rapid appearance of
biodiversity known as the
Cambrian explosion, which saw the first appearance in the
fossil record of the basic patterns and body-plans that would go on to form the basis of modern
animals. Little of the diversity of the Ediacara
biota would be incorporated in this new scheme, with a distinct Cambrian biota arising and usurping the organisms that dominated the Ediacaran fossil record. The organisms of the Ediacaran Period first appeared around
580 million years ago and flourished until the cusp of the
Cambrian 542 million years ago, when the characteristic communities of fossils vanished. While rare fossils that may represent survivors have been found as late as the
Middle Cambrian (510 to 500 million years ago), the earlier fossil communities disappear from the record at the end of the Ediacaran, leaving only controversial fragments of once-thriving
ecosystems, if anything. Multiple
hypotheses exist to explain this disappearance, including
preservation bias, a changing environment, the advent of
predators, and competition from other lifeforms.
10
Global warming is the increase in the
average temperature of the Earth's near-surface air and
oceans since the mid-twentieth century and its projected continuation. The average global air temperature near the Earth's surface increased 0.74
± 0.18 °
C (1.33 ± 0.32 °
F) during the hundred years ending in 2005. The
Intergovernmental Panel on Climate Change (IPCC) concludes "most of the observed increase in globally averaged temperatures since the mid-twentieth century is very likely
due to the observed increase in
anthropogenic greenhouse gas concentrations" via the
greenhouse effect. Natural phenomena such as
solar variation combined with
volcanoes probably had a small warming effect from pre-industrial times to 1950 and a small cooling effect from 1950 onward. These basic conclusions have been endorsed by at least thirty
scientific societies and academies of science, including all of the national academies of science of the
major industrialized countries. While
individual scientists have voiced disagreement with some findings of the IPCC, the overwhelming majority of scientists working on climate change agree with the IPCC's main conclusions.
11
Yosemite National Park (pronounced "yo-SEM-it-ee",
IPA:
/joʊˈsɛmɨtiː/) is a
national park located largely in
Mariposa and
Tuolumne Counties,
California,
United States. The park covers an area of 761,266 acres or 1,189 square miles (3,081 km²) and reaches across the western slopes of the
Sierra Nevada mountain chain. Yosemite is
visited by over 3.5 million people each year, many of whom only spend time in the seven square miles (18 km²) of
Yosemite Valley. Designated a
World Heritage Site in 1984, Yosemite is internationally recognized for its spectacular
granite cliffs,
waterfalls, clear
streams,
Giant Sequoia groves, and
biological diversity. Almost 95% of the park is designated
wilderness. Although not the first designated
national park, Yosemite was a focal point in the development of the national park idea, largely owing to the work of people like
John Muir. Yosemite is one of the largest and least fragmented
habitat blocks in the Sierra Nevada, and the park supports a diversity of
plants and
animals. The park has an elevation range from 2,000 to 13,114 feet (600 to 4,000 m) and contains five major
vegetation zones:
chaparral/
oak woodland, lower
montane, upper montane,
subalpine, and
alpine. Of California's 7,000 plant species, about 50% occur in the Sierra Nevada and more than 20% within Yosemite. There is suitable habitat or documentation for more than 160 rare plants in the park, with rare local geologic formations and unique
soils characterizing the restricted ranges many of these plants occupy.
12
Hurricane Gloria was a powerful
Cape Verde-type hurricane that formed during the
1985 Atlantic hurricane season and prowled the
Atlantic Ocean from
September 16 to
September 28. Gloria reached Category 4 on the
Saffir-Simpson Hurricane Scale near the
Bahamas, but weakened significantly by the time it made landfall on
North Carolina's
Outer Banks. From there, Gloria closely followed the
Mid-Atlantic coastline and made a second landfall on
Long Island,
New York, and, after crossing the
Long Island Sound, it made a third landfall in
Connecticut. Overall, the storm caused extensive damage along the
East Coast of the United States, amounting to $900 million ($1.6 billion in 2005
USD), and was responsible for 8 fatalities. The storm was the first significant system to impact the
northeastern United States since
Hurricane Agnes in
1972 and the first major storm to affect New York and Long Island directly since
Hurricane Donna in 1960. It was the last storm to hit the northeast until
Hurricane Bob in
1991.
13
A
geyser is a
hot spring characterized by intermittent discharge of water ejected turbulently and accomplished by a vapor phase. The name
geyser comes from
Geysir, the name of an erupting spring at
Haukadalur,
Iceland; that name, in turn, comes from the
Icelandic verb
gjósa, “to gush”. The formation of geysers requires a favourable
hydrogeology which exists in only a few places on Earth, and so they are fairly rare phenomena. There must be a volcanic heat source. Generally all geyser field sites are located near active volcanic areas. The surface water works its way down to an average depth of around 2134
m (7001
ft) where it meets up with the hot rocks. About 1,000 exist worldwide, with about half of these in
Yellowstone National Park,
U.S. A geyser's eruptive activity may change or cease due to ongoing mineral deposition within the geyser plumbing, exchange of functions with nearby hot springs, earthquake influences, and human intervention. Erupting fountains of liquefied
nitrogen have been observed on
Neptune's moon
Triton, as have
possible signs of carbon dioxide eruptions from
Mars' south polar ice cap. These phenomena are also often referred to as
geysers. Instead of being driven by geothermal energy, they seem to rely on solar heating aided by a kind of solid-state
greenhouse effect. On Triton, the
nitrogen may erupt to heights of 8 kilometres (5 mi).
14
The
geological history of Earth began 4.57 billion years ago when the planets of the
Solar System were formed out of the
solar nebula, a disk-shaped mass of dust and gas left over from the formation of the Sun. Initially
molten, the outer layer of the planet
Earth cooled to form a solid
crust when water began accumulating in the atmosphere. The
Moon formed soon afterwards, possibly as the result of a
Mars-sized object with about 10% of the Earth's mass, known as
Theia, impacting the Earth in a glancing blow. Some of this object's mass merged with the Earth and a portion was ejected into space, but enough material survived to form an orbiting moon. Outgassing and
volcanic activity produced the primordial atmosphere. Condensing
water vapor, augmented by ice delivered by
comets,
produced the oceans. As the surface continually reshaped itself, over hundreds of millions of years, continents formed and broke up. The continents migrated across the surface, occasionally combining to form a
supercontinent. Roughly 750
Ma (million years ago) (
ICS 2004), the earliest known supercontinent
Rodinia, began to break apart. The continents later recombined to form
Pannotia, 600–540 Ma (ICS 2004), then finally
Pangaea, which broke apart 180 Ma (ICS 2004). The present pattern of
ice ages began about 40 Ma (ICS 2004), then intensified during the
Pleistocene about 3 Ma (ICS 2004). The polar regions have since undergone repeated cycles of glaciation and thaw, repeating every 40,000–100,000 years. The
last glacial period of the
current ice age ended about 10,000 years ago.
15
The
geology of solar terrestrial planet mainly deals with the geological aspects of four planets of the
Solar system namely,
Mercury,
Venus,
Earth and
Mars and one terrestrial
dwarf planet,
Ceres. Objects like
Pluto are similar to terrestrial planets in the fact that they do have a solid surface, but are composed of more icy materials (see
Ice dwarf). During the formation of the solar system, there were probably many more (
planetesimals), but they have all merged with or been destroyed by the four remaining worlds in the
solar nebula. Only one terrestrial planet, Earth, is known to have an active
hydrosphere. Terrestrial planets are substantially different from
gas giants, which might not have solid surfaces and are composed mostly of some combination of
hydrogen,
helium, and
water existing in various
physical states. These planets have a compact, rocky surfaces, with the last three also having an
atmosphere. Their size, radius, and density are all similar.Terrestrial planets all have roughly the same structure- a central metallic core, mostly
iron, with a surrounding silicate
mantle. The
Moon is similar, but lacks an iron core. Three of the four solar terrestrial planets (Venus, Earth and Mars) have substantial
atmospheres; all have
impact craters and
tectonic surface features such as
rift valleys and
volcanoes. The term
inner planet should not be confused with
inferior planet, which designates those planets which are closer to the Sun than Earth is (i.e. Mercury and Venus).
16
Crater Lake is a
caldera lake located in the
U.S. state of
Oregon. It is the main feature of
Crater Lake National Park and famous for its deep blue color and water clarity. The lake partly fills a nearly 4,000 feet (1,220 m) deep caldera that was formed around 5,677 (± 150) BC by the collapse of the volcano
Mount Mazama. On
June 12,
1853,
John Wesley Hillman was reportedly the first
European American to see what he named "Deep Blue Lake" in Oregon. The lake was renamed at least three times, as Blue Lake, Lake Majesty, and finally Crater Lake. Crater Lake is known for its famous piece of
driftwood named the "
Old Man of the Lake." It is a full-sized tree that has been bobbing vertically in the lake for more than a century. Due to the cold water of the lake, the tree has been rather well preserved. While having no indigenous fish population, the lake was stocked from 1888 to 1941 with a variety of fish. Several species have formed self sustaining populations. The commemorative Oregon
State Quarter, which was released by the
United States Mint in 2005, features an image of Crater Lake on its reverse side.
17
Hurricane Lili was one of only four
Atlantic tropical cyclones on record to reach hurricane status in the month of December. The final of thirteen tropical storms in the
1984 Atlantic hurricane season, Lili developed as a
subtropical cyclone which originated from a
frontal trough to the south of
Bermuda on
December 12. It tracked southeastward, then northward, slowly attaining
tropical characteristics and becoming a hurricane on
December 20. Lili turned to the south and southwest, briefly threatening the northern
Caribbean islands before weakening and dissipating near the coast of the
Dominican Republic. Lili was the longest lasting tropical cyclone outside of the
Atlantic hurricane season, as well as the strongest hurricane to form during the month of December. It briefly threatened to pass through the
Lesser Antilles as a minimal hurricane, though upon passing through the area as a dissipating tropical depression Lili produced light rainfall and no reported damage.
18
Turquoise is an opaque, blue-to-green
mineral that is a
hydrous phosphate of
copper and
aluminium, with the
chemical formula CuAl6(
PO4)
4(O
H)
8·4
H2O. It is rare and valuable in finer grades and has been prized as a
gem and
ornamental stone for thousands of years owing to its unique hue. In recent times turquoise, like most other opaque gems, has been devalued by the introduction of treatments, imitations, and synthetics onto the market, some difficult to detect even by experts. The substance has been known by many names, but the word
turquoise was derived around 16th century from the
French language either from the word for
Turkish (
Turquois) or
dark-blue stone (
pierre turquin). This may have arisen from a misconception: turquoise does not occur in
Turkey but was traded at Turkish bazaars to Venetian merchants who brought it to Europe. The colour, however, has been employed extensively in the decorative tiles adorning Turkish places of worship and homes for hundreds of years, beginning with the
Seljuks, and the association quite possibly has caused the name to take root.
19
The
April 6-8, 2006 Tornado Outbreak was a major
tornado outbreak in the
Central and parts of the
Southern United States that began on
April 6,
2006 in the
Great Plains and continued until
April 8 in
South Carolina, with most of the activity on
April 7. The hardest-hit area was
Middle Tennessee where several strong tornadoes devastated entire neighborhoods and left nine people dead. The worst damage took place in
Gallatin, Tennessee. Other communities north of
Nashville were also hard hit. There were 73 tornadoes confirmed across 13 states, with the bulk of them coming on the afternoon and evening of
April 7 across the South, particularly in
Tennessee. In total, 13 deaths were reported as a result of the severe weather (12 of them in Tennessee) and over $1.5 billion in damage was reported,
[1] of which over $630 million was in Middle Tennessee.
[2] It was the third major outbreak of 2006, hot on the heels of
a major outbreak on
April 2. It was also considered to be the worst disaster event in Middle Tennessee since the
Nashville tornado outbreak on
April 16,
1998.
20
The
geography of Indonesia is dominated by
volcanoes that are formed due to
subduction zones between the
Eurasian plate and the
Indo-Australian plate. Some of the volcanoes are notable for their eruptions, for instance,
Krakatau for its global effects in 1883,
Lake Toba for its
supervolcanic eruption estimated to have occurred 74,000
Before Present which was responsible for six years of
volcanic winter, and
Mount Tambora for the most violent eruption in recorded history in 1815. Volcanoes in Indonesia are a part of the
Pacific Ring of Fire. The 150 entries in the list below are grouped into six geographical regions, four of which belong to the volcanoes of the
Sunda Arc trench system. The remaining two groups are volcanoes of
Halmahera, including its surrounding
volcanic islands, and volcanoes of
Sulawesi and the
Sangihe Islands. The latter group is in one
volcanic arc together with the
Philippines volcanoes. The most active volcanoes are
Kelut and
Merapi on
Java island which have been responsible for thousands of deaths in the region. Since AD 1000, Kelut has erupted more than 30 times, of which the largest eruption was at scale 5 on the
Volcanic Explosivity Index (VEI), while Merapi has erupted more than 80 times. The
International Association of Volcanology and Chemistry of the Earth's Interior has named Merapi as a
Decade Volcano since 1995 because of its high volcanic activity.
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