MEGAQUAKES ADVISORY ISSUED FIRST TIME IN JAPAN
What do we mean by megaquakes ?
Megaquake means earthquakes more than 8 or 9 magnitude such dangerous earthquakes occurs in centuries has great potential to shake the entire japan and huge tsunami waves upto 90 feet hit the coast immediately.
Why megaquake advisory in japan now ?
In 8th august 2024 an earthquake of magnitude 7.1 hit southern japan and seismic studies done in Nankai trough, a subduction zone along Japan’s south west pacific coast found that here Philippines plate get subducted under Eurasian plate created a megathrust zone. This Nankai trough causes megaearthquakes in pairs like in 1946 and 1948.
The Nankai trough produced mega earthquakes in every 100-150 years. According to 2023 study, high probability of successive big earthquakes occurrence from Nankai megathrust zone.
When will the next megaquake in Nankai trough ?
In January 2022, Japan’s Earthquake Research Committee said the next magnitude 8-9 megaquake along the trough has a roughly 70% probability of striking within the next 30 years.
What will be the adverse impact of megaquakes ?
An earthquake more than 8 or 9 magnitude will cover one third of Japan and affect one half of japan's population. such a megaquake could send tremors to areas from central Shizuoka — about 150 km south of Tokyo — to southwestern Miyazaki,
Tsunami waves of up to 98 feet may reach Japan’s Pacific coasts within minutes after the quake.
The economic damage due to the disaster could go up to $1.50 trillion, or more than a third of Japan’s annual gross domestic product.
How to predict the earthquake occurrence ?
An earthquake prediction must define 3 elements: 1) the date and time, 2) the location, and 3) the magnitude.
There is no 100% scientific method to predict and forecast an earthquake. Some methods are tried such as :
Abnormal animal behavior
P & S wave analysis and foreshock waves before hit by R & L wave or mainshock wave
Geological studies identified gaps /stress in the rock or thrust zone
Precursor emission of radon gas , the concentration suddenly increase before an earthquake in deep waterbodies.
Electro-magnetic studies is under R & D phase.
No comments:
Post a Comment