anthropologically induced geohazards and geohazards in Ireland

hazards from geo-systems

• Landslides

• Earthquakes

• Mud volcanoes

• Climate change

• Glacial melt

• Increased storms

dams

water loads behind large dams can increase stress on rocks at depth

Zipingpu dam China

• 155 m tall

• 900 million tonnes of water

• started filling reservoir in September 2005

• only 500 m from an inactive large thrust fault

Sichuan earthquake 2008

• Magnitude: 8

• Depth: 19 Km

• Killed about 69,000 people

• 4.8 million people homeless

• Rupture started 5 Km from the reservoir

• Numerical models suggest that the reservoir might have triggered the quake

can a reservoir trigger an earthquake

if high pressure water enters the fault it can reduce clamping stress on faults - lead to a rupture

geothermal energy - enhanced geothermal systems

conventional hydrothermal resources such as hot springs in geothermal area have been largely exploited

another approach to geothermal systems

fractures hot rocks at depth, then pump water through these artificially fractured reservoirs to extract heat

how is the artificial reservoir created

created by pumping high pressure water into the rock, fracturing it to improve its permeability and generating micro-earthquakes in the process

Basel Switzerland

• project initiated in 1996

• drilling of injection well reach final depth of 5 km in October 2006 (into Granite rock)

• began water injection to generate the deep fracture network on Dec 2nd 2006.

• a few hours later a Mag = 3.4 earthquake shook the town of Basel

• after a three year pause and review, project now suspended indefinitely

Lusi mud volcano Indonesia 2006

a company working in the area tried to blame the eruption on an earthquake about 200km away (which could in theory trigger the eruption)

Lusi 2006 - ongoing

Mud is currently discharged at a rate of 10,000 m3 per day, flow could continue for the next 25-30 years

other human induced hazards

• Skiers trigger snow avalanches

• Induced seismicity is a very significant hazard in deep underground mines

• Future hazards might include CO2 leakage from sequestration sites

• There are storm, flooding, water shortage and bio hazards associated with climate change

geohazards in Ireland

• Landslides - mild

• Industrial geohazards - very mild, no hazardous geo projects onshore

• Floods, moderate

• Storm hazards - significant but not severe. Lots of strong winds, but (almost) no hurricanes (it may change)

landslides

Bog slide in Pollatomish, Mayo caused by very heavy rain following an unusually dry period

flooding in Cork 2009

• communication was poor

• after that event the EPA was made responsible for coordinating geohazard response in Ireland