What are Tectonic Hazards and What Causes Them? By Philippa, Lucy and Greer

Tectonic Event ~ is a physical occurrence resulting from the movement or deformation of the earths crust..events are predominantly earthquakes or volcanic eruptions.

Hazard ~ a perceived natural / geophysical event that has the potential to threaten both life and property. Hazards occur at the interface between natural and human systems.There is a continuum from natural to quasi-natural (na-tech) to man made (D. Holmes and S.warn 2008 natural hazards and disasters)

Disaster ~ is the realisation of a hazard, when it causes a significant impact on a vulnerable population. It must kill ten or more people Affect at least 100 people Example: Haiti earthquake, 2010 magnitude of 7.0, west of capital city, deaths (D.Cowry M. Witherick Hodder Education)

1.Oceanic – oceanic plate moves under the continental plate which may trigger earthquakes. Magma rises through the cracks and erupts to the surface. E.g. Nazca plate forced under South American plate. 2. Constructive – plates move apart. Volcanoes form as magna wells up and fills the gap. E.g. Mid Atlantic rift 3. Conservative – plates slide past in opposite directions. Shock waves create earthquakes. e.g. San Andreas Fault Types of plate boundaries

Background The theory of plate tectonics and continental drift were proposed at the beginning of the last century by a German scientist, Alfred Wegener. Before his time it was believed that the planet's features, such as mountains, were caused by the crust shrinking as the Earth cooled after it was formed. It took more than 50 years for Wegener’s theory to be accepted. This was because it was difficult to work out what the mechanism was that could make whole continents move, and it was not until the 1960s that enough evidence was discovered to support the theory fully. (BBC bitesize Geography)

Crust Inner core Outer Core Mantle Convection occurs here, circular movements of the thick material in the mantle, residually move the tectonic plates

Why do plate boundaries move? Plates at our planet’s surface move because of the intense heat in the Earth’s core that causes molten rock in the mantle layer to move. It moves in a pattern called a convection cell that forms when warm material rises, cools, and eventually sink down. As the cooled material sinks down, it is warmed and rises again. (windows2universe.org)

Global Plate tectonics Global distribution: The original combination and structure of these plates was called Pangea. Ring of Fire The Ring of Fire is an area where a large number of earthquakes and volcanic eruptions occur in the basin of the Pacific Ocean (

Difference Between Volcanoes and Earthquakes There is no ostensible relation between earthquakes and volcanoes though there are zones on earth where both natural hazards are found together. Volcanoes result from openings in the surface of the earth that brings along hot magma (molten rocks) with its wake that erupts from fissures and cracks in the mountain that is referred to as a volcano. Earthquakes are a result of the tremor that is felt on the ground because of release of energy that is accompanied with breaking of rocks. The surface of the earth is not uniform inside and there is constant movement of tectonic plates inside. These plates collide with each other, resulting in violent shaking of earth that causes huge loss of property and innocent lives.

Hazard profile What is a hazard profile? The most important aspect of preparing a mitigation plan is to understand the hazards facing your community. Understanding the various hazards’ risks and consequences is the first part of mitigating the adverse effects of future events. A hazard profile is a description and analysis of a specific type of local hazard. It is performed for each natural hazard and based off of criteria such as frequency, duration, and speed of onset. Hazard profile of a volcano