# HKDSE Geography/M1/Measures Against Tectonic Hazards
## Before Hazard Occurrence
### Monitoring, Prediction and Warning

It occurs as follows:
* Geological phenomena are monitored.
* When anomalies are detected, scientists may predict a hazard.
* They issue warnings.
* Emergency work is carried out, e.g. evacuation
The following are some possible measures:
* Seismographs and satellites detect earth movement
* Foreshocks, abnormal animal behaviour and water table change are also precursors to earthquakes
* Seismic activity, water table change and volcano characteristics (e.g. unusual gases emitted, tilting, swelling, shaking, temperature and pressure change) are precursors to volcanic eruptions
* Ocean-bottom tsunami gauges and buoys satellites monitor the heights of waves in oceans.
* International warning systems (e.g. Pacific Tsunami Warning System, Regional Tsunami Warning and Mitigation System for the Indian Ocean) detects submarine earthquakes. It issues warnings to countries around the respective oceans.
* Failures and Successes
* Failed:
* Italian earthquake in 2012
* 2004 Boxing Day tsunami
* Succeeded:
* Sumatran earthquake in 2005
* Mt Pinatubo eruption
* Mount St Helens eruption 1980
* Succeeded, but still with disastrous results:
* 2011 Japanese earthquake + tsunami

### Building Design

This includes
* Developing technologies and quake-proof designs
* Legislation that mandates such designs.
Here are some examples:
* Sea walls in Japan can block tsunami waves.
* High platforms can be used for evacuation.
* In Hawaii, car parks are found on the ground floors of buildings to allow water to pass during tsunamis.
* In volcanic regions, walls are erected to block incoming lava.
* Roofs of houses are often covered in ash and may thus collapse during volcanic eruptions. Thus sloping roofs are used to shed ash.
* In earthquake-prone areas, using steel frames, soft storeys (i.e. more flexible materials) base isolation, vibration control and other earthquake-proof designs can increase the ability of a building to withstand earthquakes.

### Land Use Zoning

Risk assessment mapping is done: The chances of different areas being hit by hazards are calculated and represented as hazard maps such as volcanic hazard-zone maps. This aids in land use zoning:
* Areas with higher hazard risk are identified. They have lower-density development: fewer human settlements and industrial and commercial activities take place there. The original inhabitants may be paid a compensation to be resettled. (For example, residences along the coasts are resettled to higher ground)
* Areas with higher hazard risk cannot house certain facilities: dangerous facilities like nuclear power plants, and important facilities like hospital (which must not be destroyed during times of disaster)
* Laws governing building design are enforced in hazard-prone areas
* Evacuation routes with road signs en route are established (e.g. tsunami escape routes to higher ground).
These measures are also used for specific hazards:
* Large open spaces like parks where citizens can escape to during an earthquake.
* Schools and indoor stadia can shelter victims of earthquakes.
* Buffer zones like green belts are built to reduce potential losses.

### Education

* The government can educate citizens on the impacts of hazards, what to expect and do during hazards, etc.
* The government, schools and workplaces can also conduct hazard drills to prepare citizens for earthquakes. There may also be large-scale public earthquake drills.

## After Hazard Occurrence
### Immediate Response: Rescue Work

* Rescue teams with equipment such as life detectors, communications devices and helicopters should search for and rescue victims
* Medical services should be provided, with sufficient supplies of medicine and enough medical professionals to carry out diagnosis and treatment. (This is important as outbreaks and epidemics often occur after hazards)
* As many survivors are left homeless after the hazard, immediate aid - clean water, food and shelter - should be provided.

### Restoration/Rehabilitation, Reconstruction

* Restoration, rehabilitation and reconstruction involve repairing damaged infrastructure, reconstructing buildings and roads, and so on.
* They also involve repatriating evacuated citizens, providing counselling services for traumatised victims, etc.
* Disaster aid - donations from other nations - and insurance can help these steps financially. There are two types of international aid: Official aid (from organisations like the United Nations) and voluntary aid (from ordinary citizens of other nations).