why do volcanoes occur at plate boundaries

why do volcanoes occur at plate boundaries

Most earthquakes and volcanoes occur because of the movement of the plates, especially as plates interact at their edges or boundaries. At diverging plate boundaries, earthquakes occur as the plates pull away from each other. Volcanoes also form as magma rises upward from the underlying mantle along the gap between the two plates. We almost never see these volcanoes, because most of them are located on the sea floor. At converging plate boundaries, two situations are possible. First, both volcanoes and earthquakes form where one plate sinks under the other. This process, called subduction, takes place because one plate is denser than the other. The denser plate, which invariably has oceanic crust on its top, does the sinking. Second, only earthquakes occur when two plates

 why do you get better fuel efficiency on the highway

why do you get better fuel efficiency on the highway

The efficiency of internal combustion engines varies enormously over their range of safe operating conditions. In miles per gallon terms, of course, idling at rest is as bad as it could possible get. Manufactures take some trouble (in designing the whole powertrain) to ensure that the engine runs in relatively an efficient regime at highway speeds. Accelerating the car takes more energy than just tooling along at a steady speed (that extra kinetic energy has to come from the fuel after all), but when you brake that energy is not recovered---it is converted to heat. So city driving with it's stops and starts means that you keep pouring energy into kinetic form and then promptly converting it to heat so that you have to go get some more from the fuel tank. Over and over again. That can't be

 why do we need to study health education

why do we need to study health education

Why study health education? Through their engagement with health education, students develop the competencies to become confident, connected, actively involved, lifelong learners, ready to contribute to the future well-being of New Zealand. manage their own well-being; make health-enhancing choices, and plan, and action goals be resilient; learn to identify and minimise risks, develop strategies for coping with adversity, and access and use support, for themselves and others understand the attitudes and values that impact on well-being, such as respect, care and concern for others, and social justice contribute meaningfully and responsibly to the well-being of communities; look critically at well-being issues affecting communities, and plan and take collective action. ...

 why do you need a vent for plumbing

why do you need a vent for plumbing

An island fixture vent, sometimes colloquially called a "Chicago Loop" is an alternate way of venting the installed on an under island or other similar applications where a conventional vertical vent stack or is not feasible or allowed. As with all drains, ventilation must be provided to allow the flowing to displace the in the drain, and then to allow air (or some other fluid) to fill the which would otherwise form as the water flows down the pipe. An island fixture vent provides an elegant solution for this necessity: when the drain is opened, water displaces the sewer gas up to the, the water flows downward while sewer gas is displaced upward and toward the vent. The vent can also provide air to fill any vacuum created. The key to a functional island fixture vent is that the top elbow

 why does my dog like to lick metal

why does my dog like to lick metal

It was so professional, so personally concerned (as we were) and you answered all of our questions. George and I are so happy that I found "JustAnswer" on my Google search -- you are now in my "Favorites" list! And, yes we do love our kitty - she makes our life complete! Boca Raton, FL Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK This expert is wonderful. ...

 why does my baby spit up out of his nose

why does my baby spit up out of his nose

Spitting up differs from vomiting in that it is an effortless return of liquid rather than the result of muscle contractions. Because the throat and nose are connected, the formula or milk sometimes comes out of the nose rather than, or in addition to, the mouth. Almost all infants spit up, mainly because they cannot sit upright during feeding, but the phenomenon also can be a sign of a medical condition that requires treatment, so you should consult your pediatrician for a wellness check. Often, spitting up through the nose is harmless. The valve between the esophagus and the stomach is immature in infants, and sometimes is is not able to keep all of the stomachвs contents in place. If you feed your baby too much at a time, or if your infant eats too fast or swallows air, it can

 why does a company buy back shares

why does a company buy back shares

The main reason companies buy back their own shares is to switch cash from mature sectors and investments to new sectors or expanding companies. Share buybacks are an increasingly frequent and healthy phenomenon. When there are no investment opportunities offering a return commensurate with the required rate of return, management returns cash to shareholders, who, presumably, can find investments that meet their requirements. Here we are reminded of M. Jensen's theory of free cash flow: when a company buys back its own shares, at least it is not undertaking a risky diversification or massively over-investing! A change in the relative weighting of shareholders between those who refuse to sell their shares to the company for reasons of control (i. e. in order to increase

 why does my cat poop in the tub

why does my cat poop in the tub

This article has some good suggestions, however, the statement that some cats misbehave for no reason is completely false. Cats do not have a vindictive or revengeful nature, that said, there is always a reason for their behavior! Veterinarians and behavior specialists look at the cat's physical and emotional health, as well as traits of instinct to help figure out what's going on and find solutions. Think of this as the H. I. S. S. Test, which stands for health, instinct, stress, and symptom solvers. Cats that make a point of eliminating right in front of the owner-squatting in your presence to wet or poop may be crying out for help. Cystitis sometimes prompts cats to urinate in odd places and make a point of it by posturing in front of their human, and sometimes this is in the sink or

 why do we have air pollution problems

why do we have air pollution problems

What is the problem with air pollution? What is the problem with air pollution? Some may recall the great smogs of the 1950s which resulted in thousands of premature deaths. These pollutant laden fogs were a product of huge quantities of coal being burned for both domestic and industrial use and thankfully are a thing of the past. Since then improved legislation and tougher air quality targets have reduced such pollution episodes. Nowadays much of our outdoor pollution is a result of combustion of fossil fuels to generate power and heat and to power vehicles. Combustion results in gases such as Nitrogen Oxides, Nitrogen Dioxide and particulates. These gases may also react with other gases in the air to form secondary pollutants such as Ozone. Good air quality is essential for our health,

 why do we say that communication is a process

why do we say that communication is a process

The goal of communication is to convey information and the understanding of that information from one person or group to another person or group. This communication process is divided into three basic components: A sender transmits a message through a channel to the receiver. shows a more elaborate model. ) The sender first develops an idea, which is composed into a message and then transmitted to the other party, who interprets the message and receives meaning. Information theorists have added somewhat more complicated language. Developing a message is known as encoding. Interpreting the message is referred to as decoding. The other important feature is the feedback cycle. When two people interact, communication is rarely oneвway only. When a person receives a message, she responds to