2 Day Weather Forecast |
Graphical Presentation | Current Weather | FFA
2008-10-06.
Cool and sunny over the western parts of the country but warm later. A
band of partly cloudy weather moves in from Botswana towards the Freestate that
may lead to a few very isolated thunder storms but I do not think much rain.
Cloudy weather occurs along the south coast to the east coast due to on-shore
flow with rain patches along the coast and also a few isolated thunder storms
over the southern Karoo.
Image: 05:00 S.A.S.T.
. (Time 05:00 SAST ) copyright 2007 EUMETSAT
Magnitude 7.1 - KEPULAUAN MENTAWAI REGION, INDONESIA
2007 September 13 03:35:26 UTC
Versión en Español
Earthquake Details
|
Magnitude |
7.1 |
|
Date-Time |
- Thursday,
September 13, 2007 at 03:35:26 UTC
- Thursday, September 13, 2007 at 10:35:26 AM
at epicenter
Time of Earthquake in other Time Zones |
|
Location |
2.223°S, 99.564°E |
|
Depth |
10 km (6.2 miles) set by location program |
|
Region |
KEPULAUAN MENTAWAI REGION, INDONESIA |
|
Distances |
165 km (105 miles) SSW of
Padang, Sumatra, Indonesia
345 km (215 miles) WNW of Bengkulu, Sumatra,
Indonesia
635 km (395 miles) SSW of KUALA LUMPUR,
Malaysia
900 km (560 miles) WNW of JAKARTA, Java,
Indonesia
|
|
Location Uncertainty |
horizontal +/- 8.3 km (5.2 miles); depth fixed
by location program |
|
Parameters |
Nst=198, Nph=198, Dmin=>999 km, Rmss=1.28 sec,
Gp= 25°,
M-type=moment magnitude (Mw), Version=7 |
|
Source |
|
|
Event ID |
us2007hfax |
Earthquake Summary
The following is a release by the United States
Geological Survey, National Earthquake Information Center: An earthquake
occurred about 165 km (105 miles) SSW of Padang, Sumatra, Indonesia or about
345 km (215 miles) WNW of Bengkulu, Sumatra, Indonesia or about 900 km (560
miles) WNW of JAKARTA, Java, Indonesia at 9:35 PM MDT, Sep 12, 2007 (Sep 13
at 10:35 AM local time in Indonesia). The magnitude and location may be
revised when additional data and further analysis results are available. No
reports of damage or casualties have been received at this time; however,
this earthquake may have caused substantial damage and casualties due to its
location and size.
Earthquake Information for Asia
Earthquake Information for Indonesia
Tsunami Information
Scientific & Technical Information
Tropical Cyclones
(Extract
from the book Natural Disaster Management)
This article addresses specific windstorm known
as tropical cyclones, their inherent potential for damage and society’s efforts
for damage reduction through preparedness, mitigation and education.
Tropical cyclones are large-scale weather systems
developing over tropical or subtropical waters, where organized surface wind
circulation is present. Depending on central sustained wind speed these may be
classified as depression, storms or hurricanes,
Behold the atmosphere
One important function of the atmosphere is in
distributing energy, coming from the Sun, and in attempting to balance
temperature, pressure and moisture around the planet. The atmosphere moves air
to carry heat away from the tropics, a band of earth reaching to 23o27'
north and south of the equator, toward the polar regions where it is cooler. It
is beyond the scope of this text to describe in detail how this redistribution
of heat takes place. However it is important to note that it involves a
divergent component resulting in the movement of air away from the tropics, and
a rotational wind component resulting from the vorticity generated by the
Earth's rotation. This mechanism involves the large-scale motion known as
tropical circulation and the interaction of the atmosphere with the oceans and
land masses.
One area of concern is the interaction of
atmospheric processes with human activity. Although uncertainty remains, there
is an accumulation of scientific empirical data suggesting that human activity
may be contributing to changes in atmospheric balance. This may affect climate
and extreme weather events, if it is not doing so already. In consequence,
humankind must be observant of its role in altering important natural processes
and the need for corrective and timely actions.
Tropical cyclones are needed
Tropical cyclones are needed as an effective
method, or safety valve, for dissipating heat accumulated in the ocean and in the
tropical regions of the atmosphere. This need is evidenced by the fact that most
hurricanes take place during summer and autumn, when the tropics reach their
highest temperatures. It is then that the coupled atmosphere-ocean heat transfer
engine must be most effective in diverting heat toward the polar regions. In
some countries there is a consequential need for tropical cyclones which result
from the rains associated with these systems, that are critical for the
irrigation of crops and the production of foodstuffs to feed many millions of
people.
Cyclogenesis
Cyclogenesis refers to the formation of cyclones.
To the combination of conditions needed for cyclone formation, the area where
such conditions may be present, and to triggering events as well. Although
the main conditions and favorable areas for tropical cyclogenesis and
triggering events have been identified, the genesis of tropical cyclones is
still poorly understood. In general, tropical cyclogenesis requires:
- An area of warm sea surface water with a
thermocline of 28oCor higher
- Coinciding low atmospheric pressure
- A disturbed atmosphere with large cloud mass,
embedded rain bands and thunderstorms
- Absence of or minimal upper wind shear
- Steering winds, generally from the east
- A relative humidity of 80 per cent in the
tropical atmosphere.
These conditions are generally present in
tropical waters during summer and early fall, giving rise to an accelerated
transfer of heat from the sea surface to the tropical atmosphere creating the
energy source for tropical cyclones. Despite these ubiquitous conditions
tropical cyclones do not form spontaneously, outside triggers are needed. In the
Atlantic tropical cyclones are most often triggered by atmospheric waves moving
westward over sub-Saharan Africa.
Other phenomena, often extra-regional, have
significant influence on cyclogenesis. For example, tropical cyclone formation
in the North Atlantic is related to periodic El Nino events in the Pacific and
related to drought in the Sahel region of Africa. Empirical data clearly shows
these connections, but they are not yet fully understood.
Even under ideal conditions tropical cyclones are
relatively rare, with an average of 80 such systems forming all over the globe
in six areas known as tropical cyclone basins that include: A large portion
of the North Atlantic (including the Caribbean and Gulf of Mexico), The Western
North Pacific, The Eastern North Pacific, The Northern Indian Ocean, The
Southern Indian Ocean, and The Southwest Pacific/Australia region.
Vulnerability
Vulnerability results from the interaction of
human activity with hazards. With few exceptions, most coastal and island
regions of the world are vulnerable to tropical cyclones. Vulnerability to
tropical cyclones can be absolute or relative. Absolute vulnerability is a
function of location. For example: islands in the western Caribbean are
vulnerable to hurricanes by virtue of being located in the path of such weather
events. Relative vulnerability involves exposure to consequential hazards
resulting from the interaction of local factors, such as topographic relief, and
components of tropical cyclones such as high winds or storm surge. Such
consequential hazards include flash floods, mud-slides and beach erosion. With
regards to adverse impacts from tropical cyclone on a given location,
vulnerability must be viewed, analysed and understood, from a range of
perspectives including: a) physical, b) ecological, c) structural, d) social
(human), e) economic, and f) political aspects.
Historic
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