With reference to a range of geomorphic hazards you have studied, examine the role of human activities in both preventing and controlling this hazard type.

There are vast ranges of ways that people can be protected against the hazard or a volcano; an earthquake; or a landslide. For volcanoes prevention relies heavily on prediction as knowing where and when a volcano is going to erupt is important information in saving lives. Prediction can be achieved through satellites monitoring of heat built-up, gas emissions or ground deformation, and human monitoring can collect the same data. When a volcano does erupt, the threat of the hazard can be contained particularly through stopping the lava flow or diverting it away from a settlement, which has been a particular concern for Sicilians with the ever-present threat of the Mount. Etna volcano. One method used was to build a retaining wall around the volcano, with the come of preventing the lava from flowing beyond that point, but the wall failed because the weight of the lava flow building up behind the wall caused it to collapse. The idea wasn't bad - it was the materials that caused the project to fail, but in 1983 and 1992 a similar project using earth mounds had more success. The barriers were breached but the lava had been slowed sufficiently for it to stop before entering inhabited areas because the delay of breaching the barrier allowed the lava to cool. Other methods include the use of explosives, which had also been used when attempting to prevent the lava flows of Mauna Loa in Hawaii. The explosives widen the lava channels causing the lava to spread out more thinly which will cause it to lose heat faster and thus stop moving higher up the mountain. As bizarre as the method sounds there have been good results, particularly in the 1992 eruption of Etna. On the island of Heimaey in Iceland a lava flow not only threatened the lives of the villagers but also threatened to close one of the few deep sea ports in the region. The lava flow was basaltic lava so moved rapidly and cooled slowly so it presented a very real and dangerous threat to the people, but this threat was prevented by the Icelanders spraying the lava flow with 6 million cubic litres of sea water to cool to lava by 50 degrees. The action was a success and the Mt. Eldfell eruption did not cause lasting damage to the village and it people and the port was saved.

There is much more that humans can do to prevent the hazards posed by earthquakes, even though they are harder to predict. Retrofitting is the practice of upgrading houses to withstand the force of earthquakes and is widely used in the MEDW, particularly Kobe, Japan and California, USA. There scale of retrofitting varies widely from using shutters to cover windows that may shatter during an earthquake to prevent lethal shards of glass from falling on pedestrians to completely changing the structure of a building via replacing inflexible materials such as bricks and mortal with more flexible materials such as wood and placing large rubber pads into the foundations of buildings to absorb shocks. In the most extreme cases buildings can be designed to sway with the effects of the vibrations, such as the Transamerica Pyramid in California which swayed up to 12 feet in the Loma Preita earthquake. Unlike volcanoes there is very little that can be done to prevent the physical hazard, in this case the vibrations, but there is plenty that people can do to protect themselves. In Kobe, on the 1st September every year they hold a disaster day to educate people on what actions to take in the event of such a hazard in an attempt to prevent it from being a threat to life. The day involves practising evacuation drills and demonstrations on what vital supplies should be stored in the case of a geomorphologic hazard. Tsunamis, which generally occur as a result of deep sea earthquakes but can be the result of volcanic action, are another hazard that can be prevented from being a hazard but cannot be prevented altogether. Tsunamis cause a hazard because there is usually very little than can absorb energy once the wave hits land, but as a result of the recent Tsunami on 26th December 2004 in Asia there has been renewed interest in finding ways to prevent tsunamis from being a hazard to so many people. Because of the likelihood of tsunamis affecting lesser economically developed countries, the body of prevention research centres around using natural resources. Mangrove trees are one idea that has surfaced. Mangrove trees grow in thickets along the coast and bind the shore together with their complicated root system which also makes them very strong and able to withstand greater forces. Whilst a group of mangrove trees would not be able to withstand a tsunami, they can absorb a lot of the wave's energy substantially reducing the damage, as shown at an area named Tamil Nadu on the Indian Coast where mangrove trees did just this.

Mass movement, as already highlighted is a geomorphologic hazard that can be prevented, so not surprisingly their threat to humans can also be prevented. Mass movement is a particular threat to humans living near to base of a hill where mass movement may occur, and so it is theses areas where prevention should be concentrated. Controlling activities that are known to encourage mass movement is one of the main ways to do this and involves the reduction of ground vibrations and the management of water in the system. Ground vibrations mainly come from passing traffic and explosions at quarry's, can cause mass movement because the vibrations give soils and rocks extra energy that could trigger movement, so strategically placing roads away from hillsides where possible and re-enforcing the hillside help prevent this. Water near a hillside can lubricate material which could reduce the amount of energy needed for mass movement to occur and thus create a potential hazard. To try and prevent lubrication through water the use of tarmac and concrete in areas that may be affected can be reduced in the hope that this will allow for more water to penetrate into the soil and prevent overland flow. In other cases hillsides can be engineered to have a shallower gradient to reduce the effect of gravitational pull on material therefore preventing mass movement. Where it is not economically viable to re-enforce the whole of the hillside, segments may be re-enforced to reduce the scale, and thus the impact that mass movement may have on people.

Human activities are shown to have huge potential in the control of geomorphological hazards, particularly in the MEDW where all the new technology is financially viable. Alongside our ability to control different hazards to different degrees, human activities have also been shown to prevent geomorphic events as hazards to humans, or at least have downgraded the severity of the hazard. However, not surprisingly human activity has very little influence when attempting to prevent geomorphic hazards occurring at all. At best we can prevent some types of mass movement, but it would not be financially viable to do this for every threat, which is why it is important to develop techniques to control such events. No matter what new technology we develop, it is highly unlikely that we, as humans, will ever be able to prevent the occurrence of the two most powerful geomorphic events; volcanoes and earthquakes.