Hazards
True or False: A natural hazard is a natural phenomenon that might have a disastrous impact on people, property or the environment.
True
Volcanoes are mostly found near p______ b_______.
plate boundaries
The point at the ground level directly above the focus is called the ____________.
epicenter
For a typhoon to form, the temperature of the ocean needs to be at least ______ for a few weeks.
26 or 27°C
True or False: A landslide is the movement of rock and earth down a slope, with the help of a moving agent such as a river.
False
How are impacts categorized? (2 methods)
STEEP and long/short-term impacts
Describe 2 differences between shield and composite volcanoes.
Shield: usually at constructive plate boundaries, low elevation, wide base, gentle slopes, shorter time between eruptions, gentle eruptions, runny lava, basic lava, etc.
Composite: usually at destructive plate boundaries, high elevation, narrow base, steep slopes, longer time between eruptions, viscous lava, acidic lava, etc.
Two scales used to measure the strength of an earthquake.
Richter Scale and Mercalli Scale
Name 2 things shown on a climate graph.
temperature and rainfall
Give 3 causes of landslides (natural+human)
Removing trees allows rain to wash soil and rocks more easily downslope; The wind can push and pull at trees, making slope material less stable; Building roads on slopes cuts into the slope and makes it steeper; Heavy rainfall adds weight and lubrication to slopes; Building on slopes adds weight to them, increasing stress on the slope; Earthquakes can cause slope material to shake and fall downslope.
Preventive/remedial measures and scales of analysis (individual/local/regional scales)
Name 3 volcanic hazards.
Lava flow, ash cloud, lahar, volcanic bombs, pyroclastic flow, etc.
Explain how an earthquake forms near plate boundaries (3 steps).
1) Plates move and cause a lot of friction.
2) Plates can be stuck for a long time, building pressure.
3) When they become unstuck, this releases energy as seismic waves
What is the meaning of...
- storm surge
- torrential rainfall
- gusts
Storm surge: abnormal rise in sea level because of low pressure/winds pushing the waves onto land
Torrential rainfall: intense heavy rain
Gusts: temporary increase in wind speeds
What is the name of the government office in charge of slope safety (prevention of landslides)?
Geotechnical Engineering Office (GEO)
Give 4 examples of natural hazards besides volcanic eruptions, earthquakes, typhoons, and landslides.
Wildfire, drought, tsunami, ice storm, heat wave, avalanche, flooding etc.
Suggest 4 ways to protect people from volcanic eruptions.
Exclusion zones, setting up evacuation routes and shelters, training emergency services, educating/informing the public, monitoring systems, designing steep and smooth roofs, spraying water onto lava flows, etc.
Suggest 2 primary effects and 2 secondary effects of earthquakes.
Primary effects (immediate effects): ground shaking, buildings collapse, roads cracking, power cables damaged, deaths and injuries from building collapse, etc.
Secondary effects (long-term or caused by primary effects): landslides, fires, deaths and illnesses from exposure, liquefaction, spread of disease, homelessness, etc.
Name 4 typhoon measures (preventive/remedial)
Typhoon measures: monitoring and forecasting, emergency relief, setting up emergency response plans, education, cleaning up affected areas, housing design (raised houses/shutters), saline-resistant crops, planting mangrove forests, storm shelters, etc.
Give 3 in engineering methods to prevent landslides
Soil nails, retaining walls, covering the slope with concrete, surface channels, weepholes, flexible barriers, rigid barriers, etc.
It is a region that is vulnerable to two or more natural hazards of different types.
Explain 3 short-term impacts and 2 long-term impacts in the 2010 Eruption of Mt. Merapi.
Short-term impacts: pyroclastic flow caused deaths, people had to be evacuated, overcrowding and poor sanitation in evacuation shelters, breathing difficulties caused by contaminated air, homes were destroyed, flights were cancelled, etc.
Long-term impacts: farmers lost their livelihoods, vegetable prices increased, roads were closed, tourism developed, many households were moved to safer areas, volcano monitoring systems have been updated, etc.
Suggest 5 ways to prepare for and respond to earthquakes (preventive + remedial measures).
Monitoring and warning systems, land use zoning, shock-proof designs, education, emergency relief, rehabilitation, etc.
5 facts about Mangkhut (e.g. year, countries, hazards, and/or impacts)
Year: September 2018
Countries: Philippines and Hong Kong
Hazards: Strong winds, torrential rain, flooding, storm surge, etc.
Impacts: In HK - injuries, fallen trees, smashed windows, interrupted power supply, evacuation, cars submerged, vessels stranded/sunk/seriously damaged, agriculture affected, transport was paralyzed. In the Philippines - similar with HK but with at least 127 fatalities.
Why does Hong Kong need slope management? (3 reasons)
- lots of typhoons that bring heavy rain, which lubricates the slopes
- lots of slopes have buildings on them, adding weight to slopes
- HK has a mountainous terrain
- Big landslides cause lots of death previously