AUSTIN (KXAN) — It turns out rocks full of water might be helping to reduce the power of earthquakes near New Zealand. At UT’s Institute for Geophysics, they’ve been studying water stuck in the rocks under the ocean and how that water may be keeping stronger quakes at bay. KXAN Meteorologist Nick Bannin spoke with Andrew Gase, a postdoctoral fellow at the institute about their findings.
Nick Bannin, KXAN Meteorologist: Andrew, your research while at UT looked at the relationship between underground water and earthquakes in New Zealand, what did you end up finding?
Andrew Gase, former Postdoctoral Fellow UT Institute for Geophysics: Yeah, so in New Zealand, there’s a very large fault that’s well known for causing these earthquakes that we call ‘slow earthquakes.’ They happen over weeks to months instead of big earthquakes that caused a lot of shaking right away. And we wanted to know what’s inside the fault. And so we used a tool called ‘seismic imaging,’ and it’s kind of like medical ultrasounds. And we use that to look inside the faults, we found that there are these buried volcanoes, and they contain a lot of water within them. So we think that might play some role in the earthquake cycle.
Bannin: In this particular instance, from what I understand, you think the the presence of the water may dampen the earthquakes, is that right? But is it possible that water could enhance earthquakes in a different type of situation?
Gase: Yes. So we think that the water in these rocks is so much that it plays some role in dampening earthquakes, but also water and rocks can sometimes cause earthquakes to occur. It’s a very complicated process. We’re working with other scientists to try to figure that out. But we do think that — yes — it’s playing some role in maybe dampening earthquakes.
Bannin: So how much water did you find in places where you wouldn’t have expected [finding] that amount of water? And where do you think that water came from?
Gase: Yeah, so this, the rocks in this fault contain about twice as much water as we would normally expect. That’s about 50% of the rocks by their volume are made up of water, which is pretty unusual. And so these rocks are like sponges rather than just hard rocks. The rocks are part of this large province in the South Pacific that erupted about 125 million years ago when dinosaurs were roaming the earth. And so the water got locked into these rocks either during these volcanic eruptions that happened out on the seafloor, and then some chemical reactions occurred that locked some more of that water into the rock and these things called ‘clays.’
Bannin: As far as your findings here in New Zealand, what implications could that have on other fault lines and earthquakes in other parts of the world?
Gase: Yeah, so faultlines around the world, sometimes have different types of earthquake behaviors. Some of them cause these really large earthquakes with tsunamis and then other ones can have these slow earthquakes. And sometimes they happen both in the same place. And so we want to know if the types of rocks inside the fault plays some role in the type of earthquakes that we see. And so this has importance for other areas around the world, like in Japan or off the west coast of the US, were there are other large faults.
Bannin: It’s clear there’s more research you’re interested in doing on this topic, what needs to happen to understand this process more?
Gase: Yeah, so there are two things that I’m really interested in. I think that we should try to drill deeper into these rocks – we only skimmed the surface of them, but it’s really a mile thick layer of very water rich rocks. And we’ll be able to learn more about how it formed if we drill deeper. We could also drill deeper into the fault to see what rocks are inside the fault as you go deeper into greater depths. Another thing that I’m really interested in is there are other studies that are ongoing off the coast of Washington state and Oregon, to study what rocks are in the faults out there as well. And that could be a place where we can compare different types of earthquakes and types of faults and rocks.