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In geology, a fault is a planar fracture or discontinuity in a volume of rock, across which there has been significant displacement. Large faults within the Earth's crust result from the action of tectonic forces. Energy release associated with rapid movement on active faults is the cause of most earthquakes, such as occurs on the San Andreas Fault, California.
A fault line is the surface trace of a fault, the line of intersection between the fault plane and the Earth's surface.
Since faults do not usually consist of a single, clean fracture, geologists use the term fault zone when referring to the zone of complex deformation associated with the fault plane.
The two sides of a non-vertical fault are known as the hanging wall and footwall. By definition, the hanging wall occurs above the fault plane and the footwall all occurs below the fault. This terminology comes from mining: when working a tabular ore body, the miner stood with the footwall under his feet and with the hanging wall hanging above him.
List Of Active Fault Lines In The Philippines
Of these, the MARIKINA VALLEY FAULT poses the greatest danger because it cuts through all the modern and progressive portions of Manila such as Eastwood, Rockwell, Ortigas Center, Bonifacio Global City, Ayala Center, and Alabang. Also, the PhiVolcs people have warned that this fault line can move anytime because it is already “11 years late” for its movement.
*The earthquake that destroyed Guinsaugon is the Central Philippine Fault
*The 1990 earthquake that destroyed Central Luzon and Baguio is also the Central Philippine Fault.
An equinox occurs twice a year, when the tilt of theEarth's axis is inclined neither away from nor towards the Sun, the center of the Sun being in the same plane as the Earth's equator. The term equinox can also be used in a broader sense, meaning the date when such a passage happens. The name "equinox" is derived from the Latin aequus (equal) and nox(night), because around the equinox, the night and day have approximately equal length.
At an equinox, the Sun is at one of two opposite points on the celestial sphere where the celestial equator (i.e. declination 0) and ecliptic intersect. These points of intersection are called equinoctial points: classically, the vernal point and theautumnal point. By extension, the term equinoxmay denote an equinoctial point.
An equinox happens each year at two specific moments in time (rather than two whole days), when there is a location (the subsolar point) on the Earth's equator, where the center of the Sun can be observed to be vertically overhead, occurring around March 20/21 and September 22/23 each year.
Although the word equinox is often understood to mean "equal [day and] night," this is not strictly true. For most locations on earth, there are two distinct identifiable days per year when the length of day and night are closest to being equal; those days are referred to as the "equiluxes" to distinguish them from the equinoxes. Equinoxes are points in time, but equiluxes are days. By convention, equiluxes are the days where sunrise and sunset are closest to being exactly 12 hours apart.
The earths axis
Earth's axis is the imaginary line which goes through the north and south poles and around which Earth spins. It is inclined 66.5 degrees from Earth's orbital plane,1 which means that it is tilted 23.5 degrees from a vertical 90 degrees.
Generally, an axis is any imaginary or physical line that prescribes an object's movement. A taut string that goes through the center of a spinning ball would be an example of a physical axis. The string, as the axis, would represent the part of the ball that is not really moving or that is moving the least.
An axis also includes the point that is known as the center of gravity.
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