[Cabrera:] A wave of small earthquakes shaking Mount St. Helens in recent days, and experts say more than 100 quakes have occurred underneath the Washington state volcano over the last several weeks. So, what does this recharge mean? Let's bring in meteorologist Allison Chinchar. She is in our CNN Atlanta weather center. Allison, this seems a little bit fishy to say the least, a little nerve racking for folks on that zone.
[Allison Chinchar, Ams Meteorologist:] That's right. when you say hundreds of them, you think oh these must be big quakes. But that's just these have been incredibly small quakes. However, it's the frequency of them that have the scientists keeping a close eye on this. This is the past area over the past seven days, these blue squares that you see, those are the monitoring sites. These are all of the earthquakes that have occurred in this region in the last seven days. Now, again I want to point out, none of these have been huge. In fact, most of them have been at a magnitude of 0.5 or less. You and I can't even detect that, they're so small. Now, a maximum was around 1.3, again, very hard for humans to detect something of that small magnitude. Now, they were all shallow. Basically what this means is when you get these swarms, the repressurization of the magma that's in there, and it kind of seeps through some of the cracks that are there, and that's what causes a lot of these little mini earthquakes. But you want to keep in mind, this process is going to continue for years without the eruption. That's what they're trying to make sure that you understand. They're not expecting an eruption by any means. So, again, it sounds cool, sounds interesting, but not really a big threat at this time.
[Cabrera:] Well, thank goodness. Although you wonder, why now, why are they happening now if it's not pointing to something more imminent?
[Chinchar:] Certainly.
[Cabrera:] Thank you, Allison.
[Blackwell:] Our next hour on
[New Day:] major GOP players line up to say whether they will or will not back Donald Trump's presidential candidacy. We'll look at the divide and the challenges to unite the party.
[Cabrera:] Plus, rare access aboard a nuclear submarine. It's a CNN exclusive, next.
[Blackwell:] All right. Glad you stayed with us for this, because CNN gets exclusive underwater access to a cutting edge nuclear attack submarine. The primary mission right now is to keep a close watch on Russia and other adversaries.
[Cabrera:] And as CNN chief national security correspondent Jim Sciutto explains, the Cold War might be over, but the tensions are still bubbling beneath the surface.
[Jim Sciutto, Cnn Chief National Security Correspondent:] Victor and Ana, we have seen this confrontation between the U.S. and Russia play out in the air. You have these close flybys of U.S. and NATO aircraft by Russian planes, flybys of U.S. and NATO warships on the water, public disagreements over Ukraine and Russia. What we have not seen is what's taking place underwater, a real arms race there you could say, and we got a rare you view inside.
[Unidentified Male:] It's five and eight. You launched the open window two.
[Sciutto:] The crew of the USS Missouri nuclear attack U.S. submarine is training for war.
[Unidentified Man:] Fire. Tube two.
[Sciutto:] They simulate firing torpedoes and cruise missiles from depth, towards targets on sea and land.
[Unidentified Man:] Torpedo course 3-3-7. Unit running, wire good.
[Sciutto:] And they're constantly testing the sub's enormous speed and maneuverability. [on camera]: So we're in the midst of another steep ascent. You're hearing that alarm as we approach 20 degrees. We're going to get to a 25 degree angle. Keep in mind, I'm standing up straight now, but as I'm leaning forward, that's keeping me vertical in relation to the ground as the angle ascend gets sharper. These are just exercises, but the Missouri the "Mighty Mo" to its crew has repeatedly come nose-to-nose with real-world threats. When Russia annexed Crimea, and launched military action in Syria, the Missouri was deployed nearby. And when a Russian sub turned up off the coast of Florida in 2012, it was the USS Missouri called into action to track it. That's just showing hey, showing where they can go? [on camera]: That's a showing, hey, showing where they can go.
[Commander Fraser Hudson, Uss Missouri:] Honestly, I think it's operational experience. If anything were to ever happen, they have experience. They know those waters. I don't think it's a political statement on their part at all.
[Sciutto:] Russia is deploying attack submarines in numbers and with aggressiveness and advances in technologies not seen since the Cold War. And now, China, North Korea, Vietnam, India, and others are joining a new arms race under the sea. Commodore Ollie Lewis command a squad of ten Atlantic base subs including the Missouri.
[Commodore Ollie Lewis, Commander, Submarine Squadron 12:] We were operating on places where we didn't have to rely on an adversary being there to challenge. That's changing. We're back to the point now where we have to consider that there's an adversary ready to challenge in the undersea domain and that undersea superiority is not guaranteed.
[Sciutto:] The Missouri's greatest asset may be its silence. Invisible to satellites, virtually inaudible to other ships and subs.
[Unidentified Man:] Dive, dive.
[Sciutto:] Giving the U.S. the element of surprise.
[Hudson:] Whether there is a submarine there or not, they don't know. A potential adversary has to take that into their calculus when they make decisions to do bad things.
[Sciutto:] And so, underwater is where these boats and their crews spend 90 percent of their time deployed. So USS Missouri is coming into port now, Mayport Naval Station in Jacksonville, Florida. And that's not something if you're a submariner that you do very often. Their most recent deployment, they were out for 181 days, 163 days were at sea. That is the life of a submariner. And that is a call to action the U.S. Navy's 70 submarines are getting more and more often. [on camera]: U.S. commanders are confident that U.S. submarines maintain a technological advantage over Russian submarines, but not by much. There's a whole new class of Russian submarines.