# Could a tectonic plate on the surface of the Earth break apart. **URL:** \ **Category:** Factual Questions\ **Created:** [October 29, 2011, 5:34pm UTC](https://boards.straightdope.com/t/could-a-tectonic-plate-on-the-surface-of-the-earth-break-apart/601202 "2011-10-29T17:34:19Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![J-P\_L](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/j-p_l/32/3156_2.png) [@J-P\_L](https://boards.straightdope.com/u/J-P_L)\ **Post date:** [October 29, 2011, 5:34pm UTC](https://boards.straightdope.com/t/could-a-tectonic-plate-on-the-surface-of-the-earth-break-apart/601202/1 "2011-10-29T17:34:19Z")
This question is inspired by this [thread.](http://boards.straightdope.com/sdmb/showthread.php?t=629458) Could a tectonic plate on the surface of the Earth break apart in two or more segments. Is there any evidence that it ever occured since the formation of the planet. If it were to ever occur, what would cause such a break-up. I’m sure we can all imagine some of the after-effect of it, as in more earthquakes. ---
**Author:** ![code\_grey](https://avatars.discourse-cdn.com/v4/letter/c/f4b2a3/32.png) [@code\_grey](https://boards.straightdope.com/u/code_grey)\ **Post date:** [October 29, 2011, 5:49pm UTC](https://boards.straightdope.com/t/could-a-tectonic-plate-on-the-surface-of-the-earth-break-apart/601202/2 "2011-10-29T17:49:53Z")
not overly informative wikipedia article [List of tectonic plates - Wikipedia](http://en.wikipedia.org/wiki/List_of_tectonic_plates) notes that there are _tertiary plates_ that are embedded inside _primary plates_. E.g. the Eurasian plate has a whole lot of them. Then there is this exciting paragraph: > [@](#): > > Ancient plates and cratons > > Not all plate boundaries are easily defined, this is especially true for ancient pieces of crust. The following list of ancient cratons, microplates, plates, shields, terranes, and zones no longer exist as separate plates. Cratons are the oldest and most stable parts of the continental lithosphere and shields are the exposed area of a craton(s). Microplates are tiny tectonic plates, terranes are fragments of crustal material formed on one tectonic plate and accreted to crust lying on another plate, and zones are bands of similar rocks on a plate formed by terrane accretion or native rock formation. Terranes may or may not have originated as independent microplates since a terrane may not contain the full thickness of the lithosphere. I am not sure what to make of it all. Perhaps “define your terms and don’t disturb the good [del]doctors[/del] scientists from writing articles on some very abstruse topics”. Or maybe “no matter where an earthquake actually strikes, we will find some _cratons, microplates, plates, shields, terranes, and zones_ for a sciency explanation”. ETA: that being said, the geologists do find oil reserves and other valuable goodies using all this esoteric microplates knowledge. And that’s no small matter:) ---
**Author:** ![Foggy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/foggy/32/1082_2.png) [@Foggy](https://boards.straightdope.com/u/Foggy)\ **Post date:** [October 29, 2011, 6:10pm UTC](https://boards.straightdope.com/t/could-a-tectonic-plate-on-the-surface-of-the-earth-break-apart/601202/3 "2011-10-29T18:10:24Z")
Yes. [Juan de Fuca Plate](http://en.wikipedia.org/wiki/Juan_de_Fuca_Plate) > [@](#): > > The smallest of Earth’s tectonic plates, the Juan de Fuca Plate is a remnant part of the once-vast Farallon Plate, which is now largely subducted under the North American Plate. **The Juan de Fuca plate itself has since fractured into three pieces** , and the name is applied to the entire plate in some references, but in others only to the central portion. When the three fragments are so distinguished, the piece to the south is known as the Gorda Plate and the piece to the north is known as the Explorer Plate. The separate pieces are demarcated by the large offsets of the undersea spreading zone. Bolding mine ---
**Author:** ![paperbackwriter](https://avatars.discourse-cdn.com/v4/letter/p/53a042/32.png) [@paperbackwriter](https://boards.straightdope.com/u/paperbackwriter)\ **Post date:** [October 29, 2011, 6:14pm UTC](https://boards.straightdope.com/t/could-a-tectonic-plate-on-the-surface-of-the-earth-break-apart/601202/4 "2011-10-29T18:14:21Z")
[It’s happening right now to the African Plate](http://en.wikipedia.org/wiki/East_African_Rift): > [@](#): > > The rift is a narrow zone in which the African Plate is in the process of splitting into two new tectonic plates called the Somali Plate and the Nubian Plate, which are subplates or protoplates. ---
**Author:** ![user\_hostile](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/user_hostile/32/474_2.png) [@user\_hostile](https://boards.straightdope.com/u/user_hostile)\ **Post date:** [October 29, 2011, 6:42pm UTC](https://boards.straightdope.com/t/could-a-tectonic-plate-on-the-surface-of-the-earth-break-apart/601202/5 "2011-10-29T18:42:02Z")
There is a rift zone in southern California, called the [Brawley Seismic Zone](http://en.wikipedia.org/wiki/Brawley_seismic_zone) which delineates between the Pacific and North American Plates. It’s part of a series of _en echelon_ rift zones of the [East Pacific Rise](http://en.wikipedia.org/wiki/East_Pacific_Rise) which are sending part of California and Baja peninsula up to the northwest.