| Earth science PhD here - you're pretty much right, but Atlantic oceans can still be bad. Most earthquakes are caused by tectonic plate motion. The biggest earthquakes (>M9, e.g. Japan 2011) occur at subduction zones where an oceanic plate collides with and dives underneath a continental plate. Japan, South&Central America, New Zealand, and Malaysia are the biggest and most common examples. Two plates pushing against each other allow large energy to build, which can be released suddenly and catastrophically. Large earthquakes (M7-8, e.g. San Francisco 1906) can still occur along strike-slip faults, where two plates are sliding past each other. However, because the plates are sliding, these faults usually cannot build enough energy for extremely large earthquakes (>M9.0). San Andreas fault in California is the most well known strike-slip fault and runs through both LA and SF, and has caused plenty of damage partly because the faults run directly through population centers. The Azores lie on top of strike slip and expanding (normal) faults. Thus, they are not likely to experience the largest earthquakes (M9), but could be hit but a M8 which can still be devastating, especially if buildings are not constructed with earthquake safety in mind. In addition, there is a high risk of any earthquake triggering an underwater landslide since the Azores are a mid-ocean island chain. This could cause a tsunami which could damage far-away locations. As far as lava/ash risk -- generally the biggest risk is from explosive eruptions forming into a fast-moving cloud of ash and mud called a "pyroclastic flow" or "lahar". [1] These can travel faster than a car and blanket everything in their path in a boiling, burning cloud. Think Mt St Helens or Mt Vesuvius. However, only certain types of volcanoes are at risk of this type of eruption -- Hawaii for example erupts as smooth, oozing lava flows -- and I don't know if the Azores are at risk for this kind of eruption. Notes on safety: For earthquake safety, the best cure is preparation. Most injuries and death occur from items falling on top of people during the shaking. Secure shelves and items on walls. Avoid living in structures on poles as they are prone to collapse (e.g. apartments with parking garage on first level). Avoid living in marshy areas or seaside land constructed with landfill (due to liquefaction) or on steep slopes (due to landslides). For tsunamis, if there is a warning, head to high ground further inland if possible, or move to upper stories of the roof of structures. [1] https://www.usgs.gov/observatories/cascades-volcano-observat...
earthquake safety: https://www.calacademy.org/explore-science/how-to-prepare-fo...
tsunami safety: https://www.ready.gov/tsunamis |
The former is the boiling burning cloud of gas and tephra, the latter is a slurry of water and tephra.