residents living in the heavily populated region that faces the seismically active nankai trough havey ninety and two hundred years, and are normally accompanied by tsunamis. to understand a bit more what a megaquake is, we arejoined now byjudith hubbard — she's a geologist specialising in earthquakes and author of the substack earthquake insights. thank you for being with us. what is a major earthquake? a and are not familiar with the term —— i am not familiar with the term —— i am not familiar with the term, as it scientific or colloquial? it is kind of a new term _ scientific or colloquial? it is kind of a new term coming _ scientific or colloquial? it is kind of a new term coming from i scientific or colloquial? it is kind l of a new term coming from mega- of a new term coming from mega— thrust which is a fault that would rupture to a mega— it is a big trough and this is the nankai trough just off ofjapan. it is greater than a magnitude eight. what are the dancers in than a magnitude eight. what are the dangers in this _ than a magnitude eight. what are the dangers in this for _ t

it's a big subduction fault, in this case, in the nankai trough, offshore japan.st defined as any earthquake here that's greater than magnitude eight. and what, then, are the dangers in this forjapan, do you think? well, we've known for a long time that the nankai trough is capable of producing earthquakes of this magnitude. it's done it about 12 times since the seventh century, a couple of times in the 20th century. so it's really something that's been on our radarfor a long time. right now, we know that the earthquake risk is a little bit elevated because there has been some activity, and so that's what this advisory reflects. and it's an advisory which has been strong enough for the japanese prime minister to cancel a planned visit to central asia, as i say. but is it possible to say how accurate this warning is, whether it could happen? this is the first time that an advisory has been issued ever. this advisory system was put in place in 2019, and in part, it was inspired by the tohoku earthquake in 2011, which was preceded by a magnitude 7.2 earthquake. and s

residents living in the heavily populated region that faces the seismically active nankai trough havemally accompanied by tsunamis. do stay with us here on bbc news. i'm catriona terry, thanks for watching. bye—bye. hello there. heat and humidity is set to build as we go through the weekend, but we do need to caveat that with saturday, there is going to be quite a lot of cloud around for most of us. but it will turn increasingly very warm and very humid from sunday onwards. let's take a look at what's happening, then. this weather front will bring more cloud on saturday into south—west england and wales, and with isobars quite tightly packed together further north, that's going to feed in plenty of showers, particularly from west to east across scotland throughout the day. england and wales, quite a lot of cloud feeding in. at times, there'll be some light, drizzly rain and poor visibility through the irish sea coast there. top temperatures, though, 2a degrees. that's still 75 fahrenheit. but as we move out of saturday and into sunday, this area of low pressure is going to move in and