finding Hotspot

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finding Hotspot
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Ages and Life-cycle of Hawaiian volcanoes
MBARIs high-resolution bathymetry of Hawaii
first revealed the presence of numerous
flat-topped volcanoes on the seafloor around the
islands
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Water discoloration, sulfur odor, possible
boiling water, and possible minor floating pumice
were observed 60 km NW of the tip of Oahu on May
22, 1956. The depth at this location is about
3000 m.
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Water discoloration, sulfur odor, possible
boiling water, and possible minor floating pumice
were observed 60 km NW of the tip of Oahu on May
22, 1956. The depth at this location is about
3000 m.
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The mantle source generating the Hawaiian Islands
is chemically heterogeneous from volcano to
volcano as is well documented in numerous
studies. Moreover, growing evidence suggests that
the source also varies over time within a single
volcano
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Where in the World is Hotspot!
how do volcanoes erupt and what internal factors
make them
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Smoky Gun or a Hotspot A young man from a Chinese
ethnic minority performance group breathes fire
on the roof of a building in Chongqing
municipality in central China.
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Is Hotspot Wandering Hotspot taking Inter-Island
trips
Haleakala
Mauna Loa
Kilauea
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Oahu
Cracks on the Pacific Ocean crust
Maui Nui
Hawaii
is not fixed
Magma is created at the Mantle wedge
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The Honolulu Series of Volcanic Eruptions is
Recent, 100, 000 years old with 15 Tuff Cones in
northeast and southwest perpendicular to 3
million year old KoolausVolcanoc Series. If the
Hotspot has been active over 500,000 years under
the Big Island, 300 km away from Oahu. Other
younger volcanoes are present on Molokai and
Maui. Did the Hotspot wander to Oahu and other
Islands at the same time? NO FIXED HOTSPOT, it
is migrating along with the Pacific
Plate. Shallow oceanic crust is recycled by Plate
Subduction to make Younger volcanoes such as
Diamond Head on the older Isles.
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• Any satisfactory theory for Hawaiian volcanism
  must explain (or rationalize) the
• change in migration direction of the melting
  locus at the bend,
• association of the great bend with the Mendocino
  fracture zone,
• change in migration rate at the bend,
• apparent commencement of the volcanic chain near
  a ridge,
• absence of a plume head,
• large variations in magmatic production, and a
  current magmatic rate about 3 times greater than
  the next most productive hotspots,
• absence of a significant heat flow anomaly,
• absence of lithospheric thinning,
• absence of a strong high-temperature signal in
  the erupted basalts,

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• production of very large volumes of magma even
  though the depth to the top of the melting column
  is exceptionally large compared with MORs,
• spatial and temporal variation in the composition
  of erupted lavas on a variety of scales,
• remote location of Hawaii, near the center of a
  very large plate,
• location of the oldest end of the chain with
  respect to the Pacific pocket,
• unique rift zones,
• paired Loa and Kea trends,
• seismic whole-mantle mantle structure that is
  apparently normal compared with the Pacific ocean
  elsewhere, and
• occurrence of a bathymetric swell (a moat and
  arch) along the eastern two-thirds of the
  Hawaiian chain and wrapping around its
  southeastern end, with alkalic basaltic volcanism
  occurring at some places along it.

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In conclusion, Hawaii is not fully explained by
any current hypothesis. It is impressive that a
region of the Earth so extensively studied for so
many years, by so many Earth scientists with so
many techniques could remain so intransigent to
full understanding. Many of the numerous
features that are not yet fully understood, and
the parameters of alternative hypotheses, are not
currently being studied, but they offer exciting
research opportunities.
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Rising magma and volcanic gases exert pressure
Magma rises into reservoir beneath volcano
High pressure causes rocks to break, triggering
earthquakes
Earthquake activity beneath a volcano almost
always increases before an eruption because magma
and volcanic gas must first force their way up
through shallow underground fractures and
passageways.
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Pacific Ocean The Pacific Ocean is the largest
of the world's five oceans Location the body of
water between the Southern Ocean, Asia, Australia
and the western hemisphere Area 155.6 million
square km, or about 15 times the size of the US.
The Pacific Ocean covers about 28 per cent of the
global surface - larger than the total land area
of the world Terrain the ocean floor in the
eastern Pacific is dominated by the East Pacific
Rise, while the western Pacific is dissected by
deep trenches, including the Mariana Trench,
which is the world's deepest place Deepest
point Challenger Deep in the Mariana Trench -
11,022m
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Hotspots Lowman accepts the orthodox view that
oceanic islands and seamounts in the Pacific are
the result of the Pacific plate moving over
hotspots. This should give rise to a systematic
age progression along hotspot trails, but good
age progressions are very rare, and a large
majority show little or no age progression. The
Cook-Austral and Marquesas chains, for example,
are marked by gross violations of a simple
age-distance relationship and by extreme
variations of isotopic signature, inconsistent
with a single volcanic source. The Hawaiian chain
provides a more consistent age sequence, but the
recent renewed volcanism in the Island after a
gap of a million years does not support the
hotspot hypothesis. There is no systematic
variation of heat flow across the Hawaiian swell,
contradicting the simple hotspot model (Keith,
1993). There is no smoking gun that is puffing up
the islands, contradicting the hotspot
hypothesis origin of the Hawaiian Island
chain.
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Hotspots are commonly attributed to "mantle
plumes" rising from the core-mantle boundary.
Sheth (1999) showed that plume explanations are
ad hoc, artificial, and inadequate, and that
plumes are not required by any geological
evidence. A mantle plume from a deep hotspot
would broaden upward as a result of drag forces,
and would attain a surface width of several
hundred kilometres, far beyond oceanic island
dimensions. It is therefore claimed that hotspot
tracks are produced by plume tails but the
problem of what has happened to ancient and
modern plume heads remains unsolved. It is
significant that many ocean island chains are
found along fracture zones, and flood basalt
provinces are at orthogonal intersections of the
fracture zones (Smoot, 1997). A credible
alternative explanation is that hotspot tracks
are produced by propagating rifts, and delineate
the stress field, not the displacement field, of
the lithosphere (Sheth, 1999). In surge
tectonics, linear volcanic chains are believed to
be produced by magma surge channels in the
lithosphere (Meyerhoff et al., 1996). There
is a major controversy among plate tectonicists
as to how fast hotspots move relative to one
another one group believes that hotspots move at
3 mm/yr or less, whereas the other believes that
hotspots move at 10-20 mm/yr or more. These
differences are partly the result of "plate
reconstruction" uncertainties (Gordon, 1995
Baksi, 1999
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Giant blocks in the South Kona Landslide, Hawaii
James G. Moore, Wilfred B. Bryan, Melvin H.
Beeson, and William R. Normark U. S. Geological
Survey, Menlo Park, CA, United States Geology
February 1995 v. 23 no. 2 p. 125-128 A large
field of blocky sea-floor hills, up to 10 km long
and 500 m high, are gigantic slide blocks derived
from the west flank of Mauna Loa volcano on the
island of Hawaii. These megablocks are embedded
in the toe of the South Kona landslide, which
extends approximately 80 km seaward from the
present coastline to depths of nearly 5 km. A
10-15-km-wide belt of numerous, smaller,
1-3-km-long slide blocks separates the area of
giant blocks from two submarine benches at depths
of 2600 and 3700 m depth that terminate seaward
20 to 30 km from the shoreline