Seventy-five percent of Earth’s volcanoes—more than 450 volcanoes—are located along the Ring of Fire. Ninety percent of Earth’s earthquakes occur along its path, including the planet’s most violent and dramatic seismic events.

Oceanic plates are formed by divergent plate boundaries. Continental plates, meanwhile, are formed primarily by convergent plate boundaries. These zones represent areas where oceanic plates collide with and plunge underneath continental plates – a process called subduction.

When an oceanic plate converges with a continental plate, the oceanic crust will always subduct under the continental crust; this is because oceanic crust is naturally denser. Convergent boundaries are commonly associated with larger earthquakes and higher volcanic activity.

When oceanic crust converges with continental crust, the denser oceanic plate plunges beneath the continental plate. This process, called subduction, occurs at the oceanic trenches. The subducting plate causes melting in the mantle above the plate. The magma rises and erupts, creating volcanoes.

Japan lies along what is called the Pacific Ring of Fire, an imaginary horseshoe-shaped zone that follows the rim of the Pacific Ocean, where many of the world’s earthquakes and volcanic eruptions occur. According to the U.S. Geological Survey, 81 percent of the world’s largest earthquakes happen in this belt.

Typically, you can receive an epidural as early as when you are 4 to 5 centimeters dilated and in active labor. Normally, it takes about 15 minutes to place the epidural catheter and for the pain to start subsiding and another 20 minutes to go into full effect.

“It’s too late for an epidural when women are in transition, which is when the cervix is fully dilated and just before they start pushing. Transition is the really intense bit when lots of women ask for epidurals. “An epidural can be effective within 25 to 30 minutes of an anaesthetist walking into a hospital room.

It’s never too late to get an epidural, unless the baby’s head is crowning, says David Wlody, Chair of the Department of Anesthesiology at SUNY Downstate College of Medicine. It takes as little as ten to 15 minutes to place the catheter and start getting relief, and another 20 minutes to get the full effect.

During active labor, your cervix will dilate from 6 centimeters (cm) to 10 cm. Your contractions will become stronger, closer together and regular. Your legs might cramp, and you might feel nauseated.

Potential etiologies for long-term complications associated with ESI include infection, bleeding, endocrine effects, neurotoxicity, and neurologic injury.