EMERGENCY RISK REDUCTION

Earthquakes involve the powerful movement of the Earth’s crust, when two blocks of rock suddenly slip past one another.  The rapid release of energy creates seismic waves that travel through the earth.  The damage caused by earthquakes depends on their depth and fault type, as well as the geology of the region. Scientists use seismometers determine the energy released and locate the epicenter, or the point on the surface directly above where the earthquake originated. This is done by measuring different speeds of seismic waves.

An example is Banda Aceh, a hard-hit city on Sumatra’s west coast. The December 2004 earthquake that occurred in the Indian Ocean was estimated at 9.1. When I arrived, I was surprised at the relative lack of damage of buildings from the earthquake itself. Most of its energy had been absorbed by the water, which triggered a series of tsunamis that killed over 200,000 people in 14 countries. The overwhelming death and destruction was from three huge waves that hit the Indonesian shoreline.

More recently, the earthquake that hit the Tohoku region of Japan on March 11, 2011 had a magnitude of 9.0 and killed over 15,000 people. Japan is very well prepared for earthquakes due to their frequency.  The destruction caused by the Tohoku earthquake was primarily from a tsunami created due to its offshore epicentre.

The most powerful earthquake ever recorded was in Valzia, Chile. Occurring in 1960, it had a magnitude of 9.5. Understand that the Richter Scale is exponential, meaning that a 7.0 is 10x greater than a 6.0 in “energy” released by the quake. An 8.0 is 10x greater than a 7.0, and so forth. Any quake above 7.0 is vast; a quake above 8.0 is enormous;  a quake above 9.0 is of biblical proportions.

An excellent example of the destruction possible in North American cities occurred in Christchurch, New Zealand a couple of years ago. A February 2011 earthquake followed nearly 6 months after a magnitude 7.1 earthquake shook the region. The earthquake killed 181 people and significantly damaged the central city. The economic damage caused by the earthquake and aftershocks is estimated to be around $15 billion (NZ$).  An earthquake that hit Haiti in January 2010 was actually smaller than the NZ quake, with a magnitude of 7.0, yet it killed over 200,000 people. This clearly shows the importance of enforced building codes and good engineering practises to keep buildings from collapsing.

It is important in earthquake prone regions such as the Pacific Rim and the west coast of North America to build structures that react well to earthquakes . I live near Vancouver, BC, and seismic upgrading is slowly taking shape.  Since we live in an earthquake zone, we must be knowledgeable. A few suggestions:  During a quake, if you are in a building, stay inside. Do not immediately run out, as debris may be falling from the exterior walls. Duck, cover, and hold. Duck under a heavy desk or table, cover you head and torso, and hold onto the furniture. If you can’t get under something strong, go next to an interior wall and sit with your bottom and feet flat on the floor, and protect your head. Stay away from windows. If you are outside, go to an open area. Stay far away from buildings or any structure that could collapse. If you are in a car, stop somewhere clear of overpasses, bridges, and power lines, and stay inside your vehicle.

Seismologists predict a 33% chance of a ‘Big One’ happening somewhere along the US/Canada west coast within 50 years. We simply don’t know when, where, or how severe. However, a bit of knowledge, awareness, seismic upgrading of buildings, and personal preparedness will allow better sleep at night.

Thanks for reading.