Today’s earthquake that occurred just off the Kamchatka peninsula is a large magnitude event (M8.8), and occurred on a subduction zone where the Pacific Plate is diving down under the Okhotsk Plate – and because it was offshore, it generated a tsunami.

According to the USGS, the area has a relatively small population, so damage or injuries to local people and property isn’t expected to be too large. The US Pacific Northwest and Alaskan coasts are under a Tsunami Advisory, with waves of less than 1 ft expected in some northern areas, with Crescent City (a promontory on the Oregon Coast) having the largest predicted waves of up to 4.8 ft (USGS).

At last count, there have already been 10 aftershocks above magnitude 5, the largest at M6.9. This demonstrates that large magnitude earthquakes generate aftershock sequences that start immediately, and some of these can be damaging in their own right. From the perspective of local people, their experience of this earthquake is going to be compounded in the coming weeks, months and years by on-going aftershock activity, which can have a significant psycho-social affect.
 
"Aotearoa lies just over 9,600 km from the epicentre, with nothing but the Pacific Ocean between us. New Zealand is no stranger to the effects of distant tsunami events, for example our experience of the 1960 M9.6 Chilean earthquake. Waves of up to 5.5m in some coastal locations took 10-12 hours to cross the Pacific Ocean to reach our shores. The NEMA mobile phone alert that came out this afternoon urged people not to go tsunami sight-seeing at the coast. Let’s take heed of this warning, and show that we have learnt something about tsunami risk by keeping clear of any waves or strong currents on our beaches, inlets and other coastal locations.