3Qs: Earthquake not surprising, but tough to predict

An earthquake struck in Virginia yesterday afternoon and was felt up and down the East Coast. We asked Jerome Hajjar, chair of the Department of Civil and Environmental Engineering, to assess Tuesday’s earthquake and discuss how buildings in older cities such as Boston are equipped to resist events.

Was the East Coast due for an event like this? Are you surprised by its magnitude?

I was not surprised. The East Coast, stretching from Canada to Florida, has potential for earthquakes, with the most likely locations for relatively large earthquakes being the South Carolina coast and the Quebec area. Because larger earthquakes do not occur on the East Coast with the same frequency as they do in high seismic zones in other parts of the world, it is harder for us to determine the frequency and likely peak magnitude of these events, but we do know that moderate and possibly larger earthquakes (magnitudes greater than 6.0) are certainly possible and are potentially likely on the East Coast.

What is the scope of structural and non-structural damage that can be expected from an earthquake in this particular region of the country?

Depending on when and where the earthquake strikes, an event of this size can certainly create significant non-structural damage near the epicenter (i.e., damage to interior walls, building cladding, toppled contents, etc.). Moderate to severe structural damage is also possible near the epicenter, particularly for vulnerable structures, such as older masonry and lightly reinforced concrete structures or steel structures made with brittle weld metal or fracture-critical details – including buildings, bridges, elevated roadways and other parts of the infrastructure.

From an engineering perspective, are older American cities prepared for these kinds of events? Are newer buildings in these cities being built with resistance measures in mind?

Engineers in Boston, New York and other parts of the East Coast are certainly aware of the potential for these types of hazards; that is why how best to safeguard against earthquakes is often discussed on the state code committees and in the engineering community. We have the challenge of balancing the need to ensure safe construction, while keeping in mind the public perception that the threat of earthquakes in this part of the country is low. As we saw yesterday – the threat is there and documented.

Older cities are certainly vulnerable to these events due to the fact that portions of their infrastructure may not have not been adequately assessed and retrofitted. Our region would benefit from a more active program in research to develop cost-effective retrofit strategies for structures on the East Coast, coupled with code requirements or incentives to enable these retrofits. While newer structures can often be safer, significant work remains to develop and implement effective solutions for mitigating the potential threats posed by earthquakes in the Northeast and across the East Coast.