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1. The first topic of earthquake.An earthquake (also known as a quake, tremor or temblor) is the result of a

sudden release of energy in theEarth'scrust that createsseismic waves.

The seismicity, seismism or seismic activity of an area refers to thefrequency, type and size of earthquakes experienced over a period of time.

Earthquakes are measured using observations fromseismometers.

Themoment magnitude is the most common scale on which earthquakes

larger than approximately 5 are reported for the entire globe. The more

numerous earthquakes smaller than magnitude 5 reported by national

seismological observatories are measured mostly on the local magnitude

scale, also referred to as theRichter scale. These two scales are

numerically similar over their range of validity. Magnitude 3 or lower

earthquakes are mostly almost imperceptible or weak and magnitude 7 and

over potentially cause serious damage over larger areas, depending on

their depth. The largest earthquakes in historic times have been of

magnitude slightly over 9, although there is no limit to the possible

magnitude. The most recent large earthquake of magnitude 9.0 or larger

was a9.0 magnitude earthquake in Japan in 2011 (as of October 2012),

and it was the largest Japanese earthquake since records began. Intensity

of shaking is measured on the modifiedMercalli scale.The shallower an

earthquake, the more damage to structures it causes, all else being equal.

At the Earth's surface, earthquakes manifest themselves by shaking and

sometimes displacement of the ground. When theepicenter of a large

earthquake is located offshore, the seabed may be displaced sufficiently to

cause atsunami.Earthquakes can also trigger landslides, and occasionally

volcanic activity.

In its most general sense, the word earthquake is used to describe any

seismic event whether natural or caused by humans that generates

seismic waves. Earthquakes are caused mostly by rupture of

geologicalfaults, but also by other events such as volcanic activity,landslides, mine blasts, andnuclear tests.An earthquake's point of initial

rupture is called itsfocus orhypocenter. Theepicenteris the point at

ground level directly above the hypocenter.

2. The Second topic of GeothermalGeothermal energy is thermal energy generated and stored in the Earth.

Thermal energy is the energy that determines thetemperature of matter.

The Geothermal energy of the Earth's crust originates from the original

formation of the planet (20%) and fromradioactive decay of minerals

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(80%).[1][2] Thegeothermal gradient, which is the difference in

temperature between the core of the planet and its surface, drives a

continuous conduction of thermal energy in the form ofheat from the core

to the surface. The adjective geothermal originates from the Greek roots

(ge), meaning earth, and (thermos), meaning hot.

At the core of the Earth, thermal energy is created byradioactive

decay[1] and temperatures may reach over 5000 C (9,000 F). Heat

conducts from the core to surrounding cooler rock. The high temperature

and pressure cause some rock to melt, creatingmagma convection upward

since it is lighter than the solid rock. The magma heats rock and water in

the crust, sometimes up to 370 C (700 F).

Fromhot springs, geothermal energy has been used for bathing

sincePaleolithic times and forspace heating since ancient Roman times,

but it is now better known for electricity generation. Worldwide, about

10,715megawatts (MW) of geothermal power is online in 24 countries.

An additional 28 gigawatts of directgeothermal heating capacity is

installed for district heating, space heating, spas, industrial processes,

desalination and agricultural applications.

Geothermal power is cost effective, reliable, sustainable, and

environmentally friendly, but has historically been limited to areas

neartectonic plate boundaries. Recent technological advances havedramatically expanded the range and size of viable resources, especially

for applications such as home heating, opening a potential for widespread

exploitation. Geothermal wells release greenhouse gases trapped deep

within the earth, but these emissions are much lower per energy unit than

those of fossil fuels. As a result, geothermal power has the potential to

help mitigateglobal warming if widely deployed in place of fossil fuels.

The Earth's geothermal resources are theoretically more than adequate to

supply humanity's energy needs, but only a very small fraction may be

profitably exploited. Drilling and exploration for deep resources is veryexpensive. Forecasts for the future of geothermal power depend on

assumptions about technology, energy prices, subsidies, and interest rates.

Pilot programs like EWEB's customer opt in Green Power Program show

that customers would be willing to pay a little more for a renewable

energy source like geothermal. But as a result of government assisted

research and industry experience, the cost of generating geothermal power

has decreased by 25% over the past two decades. In 2001, geothermal

energy cost between two and ten cents per kwh.

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