Earthquake

[dakine]

quote:

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Originally posted by faroutsider

When the lava lake went down recently, the lava was thought to be underground in that area and there were many small quakes in that area as well.

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That's not completely accurate.

The earthquakes during the swarm being referred to were concentrated along the Upper East Rift Zone but they stopped near Pauahi Crater, which is two miles mauka of the point at which today's event occurred. That is also the extent of where magma was thought to have migrated as well.

Todays earthquake was located in an area that has produced events of this size, and at the same depth (8 - 10 km) repeatedly over the years, at least as far back as the onset of activity at Puu Oo. It is generally believed that they are associated with the widening of the East Rift between Pauahi Crater and Puu Oo.

Often times when we have these events they will be followed by a similar sized earthquake, at a similar depth, in a location just south of Puu Oo/Kupaianaha in a few weeks to a month later.

[Punatic007]

quote:

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Originally posted by msrocket

Didn't we just have a June 27 2014 lava flow?

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First thing I thought of after the rumbling....wonder if we'll have a new flow?

[PunaMauka2]

Kilauea summit area was rocked. short but attention-grabbing, with a jolt of adrenaline. i had overestimated a little in guessing 5.5

no chorus of coquis to silence, but i wonder if the same happens with crickets?

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[PunaMauka2]

friend of mine who periodically works in geology on the side told me the EQ was tectonic and not volcanic(due to movement of magma). if so, not surprising coming from Hilina Pali area.

just relaying what i was told, please correct if inaccurate.

[TomK]

Well, I just learned something. When I saw "tectonic earthquake" I thought no way, as those are created at the boundaries of tectonic plates. However, it seems you can get volcano tectonic earthquakes caused by magma, according to wikipedia at least.

https://en.wikipedia.org/wiki/Volcano_te...earthquake

That article references this paper which I haven't read yet:

http://jclahr.com/alaska/aeic/redoubt/JVGR1994.pdf

[faroutsider]

quote:

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Originally posted by dakine

quote:

---

Originally posted by faroutsider

When the lava lake went down recently, the lava was thought to be underground in that area and there were many small quakes in that area as well.

---

That's not completely accurate.

The earthquakes during the swarm being referred to were concentrated along the Upper East Rift Zone but they stopped near Pauahi Crater, which is two miles mauka of the point at which today's event occurred. That is also the extent of where magma was thought to have migrated as well.

Todays earthquake was located in an area that has produced events of this size, and at the same depth (8 - 10 km) repeatedly over the years, at least as far back as the onset of activity at Puu Oo. It is generally believed that they are associated with the widening of the East Rift between Pauahi Crater and Puu Oo.


Often times when we have these events they will be followed by a similar sized earthquake, at a similar depth, in a location just south of Puu Oo/Kupaianaha in a few weeks to a month later.

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Thank you for the information! So interesting and exciting. I've never felt such a BIG one. #128516;

[dakine]

the EQ was tectonic and not volcanic(due to movement of magma)...

I think that's an odd use of the term...

The earthquake was at a depth of about 8km, which is about the point of the decollement plane, i.e. the bottom of the volcano as it sits on the Earth, and most likely caused by the movement of the south flank of the volcano, not the underlying tectonic plate.

The question has always been are these earthquakes pushed, as if the pressure of magma within the volcano on one side (to the north) pushes the block of rock outward (to the south) or pulled but gravity as the unsupported southern flank of the volcano slips away. Though the end result, which is the widening of the East Rift Zone as the southern flank migrates south is still the same regardless of which force is at the root of the event.

So, if your friend is one of the gravity induced group I suppose it could be called tectonic, but still it was the volcano that moved, and that coupled with the fact that there was recently a large influx of magma in the area (just north of the epicenter) I'd place my bets on volcanic.

fyi.. a simplified drawing of a cross section of Kilauea Volcano along with a discussion of this topic can be found in a paper titled New insights into Kilauea's volcano dynamics brought by large-scale relative relocation of microearthquakes and read online here:

http://onlinelibrary.wiley.com/doi/10.10...02060/full

[PunaMauka2]

it was a brief casual conversation amongst a few of us, his main point as i understood it being that the EQ was generally the result of the weight of the island on the crust rather than an indication of some sudden subterranean intrusion of magma. though i could see how it often might not be the case of one or the other, but sometimes rather both - a settling triggered by magma intrusion.

was his assessment correct? i don't know. sounds reasonable though.


my impression was he was using the term tectonic in a broader sense in casual, less technical conversation...

1.Geology - of or relating to the structure of the earth's crust and the large-scale processes that take place within it.

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https://en.wikipedia.org/wiki/Volcano_te...earthquake

volcano tectonic earthquake... that's new to me, also. the term almost sounds like an oxymoron on the surface of it.

[PunaMauka2]

yes, it was a brief casual conversation ...kind of like it was here.

...take it away, dakine.