We are a small team of engineers, programmers, and designers who care about the safety and earthquake resilience of the residents of BC. We are a part of PBRV Consulting Ltd., an earthquake engineering company based in Vancouver, BC. We are developing this tool as a way of spreading awareness about earthquake safety.

Our assessments are of the same standards as the ones used for the BC School Seismic Mitigation Program initiated by the BC Ministry of Education. The Association of Professional Engineers and Geoscientists of BC (APEGBC) and the University of British Columbia (UBC) developed the program. Our lead engineer Dr. Freddy Piña was one of the key researchers who developed the methodology. We format the assessment so that it is accessible and understandable for the general public— like you.

We did consider the “big one” in the assessment. In fact, we considered different types/sources of earthquakes - you might have heard about crustal, subcrustal, and subduction earthquake, and all levels of shaking - from the lowest to the most intense. And a side note, we are not predicting earthquakes; we are taking consideration of the long term behaviour of the seismic sources.

Well, that is a pretty isolated story. Different locations have different seismic hazard. Different houses have different structural system and content. So eventually the risk and the consequences are different. Your cousin’s friend’s parents’ home passed its own earthquake test; but for the rest of us, we do not know.

We got rid of the confusing numbers and complicated science-y jargon, and give you a simple scoring system to see how fit your house is, and whether you need to retrofit/upgrade your house or not. “Green” score means your house should be safe in the sense that it has a low chance that the structural system will experience considerable damage, and that your house meets the life-safety standard. However, you may still experience some monetary loss from damages on the non-structural elements and the content of your house. “Yellow” score means your house may or may not collapse, and you will experience some monetary loss from damages on the non-structural elements and the content of your house. Retrofitting is recommended for the house to meet the life-safety standard and to minimize damage/losses. “Red” score means your house has a pretty high chance of the structural system will experience considerable damage up to the point of collapse. It is highly suggested that you retrofit your house. Our scoring system gives you a glimpse of the seismic hazard and risk of your house. Technically speaking, hazard and risk are two different things.

For engineers, seismic hazard and risk are two different things. Seismic hazard is the chance of an earthquake occurring and shaking your house; it is a pure probability statistical thing. Risk is the consequence or outcome from the hazard. For instance, we defined seismic hazard as the probability of drift exceedance (PDE) of the house. The risk may be the expected loss from damages, which can be calculated by combining the probability of drift exceedance (PDE) with cost of house content, structural, and non-structural damages. Probability of drift exceedance (PDE) is the probability that your structure is drifting more than its allowable drift limit. Sorry it’s starting to get more technical :(.

The building life-safety standard in Canada for earthquakes is taken as 2% chance of exceedance in 50 years. The structure may be heavily damaged, but it should be good enough so that you can survive the earthquake hence the term life-safety. This 2% chance in 50 years is the equivalent of designing a structure for a very large earthquake. Statistically speaking 2% in 50 years is equivalent to 0.0404% in 1 year (or an annual rate of 1 in 2475). You can do conversion with Poisson point process if you’re math-y. To elaborate more on the 2% chance in 50 years: Within 50 years, there is any earthquake of any intensity level may occur. With those earthquakes, your house will deform and drift. If the probability that your house is drifting less than the allowable drift limit is lower than 2%, that means your house has met the life-safety standard.

We want to show you a comparison of commonly-known everyday hazards with the seismic hazard of your house. The comparison of your house’s seismic hazard with these equivalent scenarios are statistical but can give you an idea of how likely things are to occur.

We decided on some equivalent scenarios, and crawl around to find the information about them. We make sure that the sources come from legitimate organizations. Here is the complete list of scenarios, along with the numbers and sources