US-bound Hurricane Irma has gotten so strong that it is showing up on equipment designed to measure earthquakes.

Stephen Hicks, a seismologist at the National Oceanography Centre Southampton, said seismometer recordings on Guadeloupe, an island group in the southern Caribbean Sea, show the now-Category 5 storm approaching the Lesser Antilles, another Caribbean island group.

“Seismometer recordings from the past 48 hours on Guadeloupe show Cat. 5 #Hurricane #Irma driving closer toward the Lesser Antilles,” Dr Hicks tweeted.

Irma, which is already the strongest hurricane ever recorded outside the Caribbean and the Gulf of Mexico, is likely to make landfall somewhere in Florida over the weekend.

Hurricane Irma is so strong it’s starting to show up on seismometers in the Caribbean — equipment designed to measure earthquakes. https://t.co/qJrSJ1v8gy

— Eric Holthaus (@EricHolthaus) September 5, 2017

Florida, Puerto Rico and the US Virgin Islands have declared states of emergency.

Rick Scott, the governor of Florida, has said Irma’s exact path is unknown, but that the storm could affect “millions of Floridians”.

Because of Irma’s size and power, very dangerous weather could also occur up to 200 miles away from the eyewall, the most devastating region of a hurricane.

“The hurricane force winds in Irma are wider than Florida,” tweeted Bryan Norcross, hurricane specialist at the Weather Channel. “You won’t need a direct hit to get Wilma-type winds & storm surge on both coasts.”

As Florida and nearby states and territories prepare to be battered by Irma, Texas continues to reel from the devastation caused by Hurricane Harvey in August.

Texas Governor Greg Abbott has suggested repair costs could total $180bn. Donald Trump sent Congress a $7.9bn request for an initial down payment for Harvey relief and recovery efforts.