L16 Anthropogenic caused geohazards

What is infrastructure that can cause eqarthquakes?

Dams

How do dams works?

water loads behind a large dam + can increase stress if rocks at depth

Zipingpu Dam, China

• developed 2,000 years ago

• 155m high

• holds 900m tonnes of water

• In an area with active faults

• 50mm from ‘inactive’ large thrust fault

When was the Sichuan Earthquake?

12th May 2008

What was the magnitude of the earthquake?

8Ms

How many people did it kill?

~69,000

What was the depth of the earthquake?

19km

How far away was it from fault?

Rupture 5km from reservoir of 'inactive' fault  

What are the possibility of the reservoir triggering an earthquake?

• high pressure water enters fault which reduced clamping stress on fault

• In an unstable system a rupture can ‘run away’ and become big earthquake

• water loads can also

What are other human induced hazards

landslides → poor engineering

snow avalanches → skiers

induced seismicity → underground mines

CO2 leakage → sequestration sites

storm, flooding, water

How does enhanced geothermal systems work?

fracturing of hot rocks at depth, pumping water to extract heat

Basel Switzerland

• initiated 1996

• 10 years of planning

• 5km into granite rock, Oct 2006

• water injection started Dec 2nd 2006

  → immediate microearthquakes

• Stopped injection dec 7th as could feel earthquakes

  → magnitude of 3.4

• project suspended indefinitely

Lusi mud volcano, Indonesia

• erupted in 2006

• eruption triggered by exploration drilling for gas

• still ongoing in 2016

• discharged at rate of 10,000m3 per day

• flow for next 25-30 years

Earthquakes In Ireland

negligible

Volcanoes in Ireland

Zero, last eruption ~60m years ago

Landslides in Ireland

mild, few steep mts with populated valleys

Industrial geohazards

very mild

Floods

moderate, could be life-threatening

storms

significant but not severe