Natural stuff in the news: Bahama damage from Hurricane Dorian

1. Natural stuff in the news: Bahama damage from Hurricane Dorian

2. HAWAIIAN LAVA FLOWS - Scott K. Rowland, University of Hawai‘i at Manoa For best results, install the font file (TECHNCLN.TTF) that is in this same directory.

3. - - Lava flows: ‘a‘a and pahoehoe - ‘a‘a: 1. To burn, blaze, glow; fire; staring, as eyes. Fig., angry, fury. Ua ‘a‘a ‘ia au i ke aloha (I burn with love). 2. stony, abounding with ‘a‘a lava. - - - pahoehoe: 1. Smooth, unbroken type of lava. 2. Satin. 3. to drive fish into a net by beating the paddles rhythmically against the canoe. From Hawaiian Dictionary by M.K. Puku‘i & S.H. Elbert

4. - - Lava flows: ‘a‘a and pahoehoe - - - Pahuhu: to gush, ooze forth Ho‘opohaku: to harden, as lava - These two types of flow are identical chemically, their differences are due to different emplacement processes (flow rates, cooling rates, etc.). (Courtesy of Ululani Makue)

5. - ‘a‘a - pahoehoe -low volumetric flow rate (<10 m3 s-1) -low flow-front velocity (1-10 m hr-1) -develops lava tubes -innumerable flow units -thin (10-100 cm) flow units -lower viscosity -lower yield strength -slightly hotter -“helluhraun” (pavement lava) in Icelandic -high volumetric flow rate (10-103 m3 s-1) -high flow-front velocity (102-104 m hr-1) -develops large channels -few, large flow units -thick (1-10 m) flow units -higher viscosity -higher yield strength -slightly cooler -“apaluhraun” (rough lava) in Icelandic These terms are “…the barbarous expressions of an insignificant and uncivilized race in a small archipelago in the Noth Pacific…” (Bonney, 1899)

6. - Pohaku ‘elekū, lots of vesicles, easy to shape by “pecking”, (usually the interior of a pāhoehoe flow) Pohaku ‘alā, few or no vesicles, breaks along planar fractures, difficult to shape but good for cutting tools (the core of an ‘a‘ā flow or dike rock) - Stone for making implements: Note that the personal preferences of the stone worker entered into the decision as well, as shown by portions of an interview of Herbert Kuumi Kin In (HKI) by William Meinecke (WM) and Mary Kawena Pukui that contains the following: WM: Ah no, the ‘āla was too smooth. Stones with little holes, that’s this. HKI: Yes, coarse, vesicular basalt. That is the pōhaku ‘elekū WM: ‘Elekū, that’s right. HKI: Good stone for hewing. Pōhaku ‘alā, hard, one has to handle carefully they break. WM: There’s one fault, that makes people dislike the ‘alā, because it’s not porous at the base, and the stone slips when pounding poi. HKI: Ah, I prefer the ‘alā. (Bishop Museum Archives Manuscript/Typescript no. HAW ID5.7.1, typescript pp. 18-19)

7. - - ‘a‘a and pahoehoe flows on the north flank of Mauna Loa ~3 m

8. Wave-cut cliff section, Makapu‘u, O‘ahu

10. - ‘a‘a flows

11. - Proximal-type ‘a‘a flows -relatively thin -vesicular interior -thin top and bottom clinker layers

12. When moving, the incandescent interior is deforms fluidly ~1 m

13. The top surface is relatively small, spiny clinkers

14. - Distal-type ‘a‘a flows standard geologists for scale

15. - Distal-type ‘a‘a flows: -dense, angular, large surface blocks -incandescent lava has a high yield strength -advance is by avalanching of loose blocks and fine material

16. George Walker, walking around on the surface of the (active) 1984 Mauna Loa distal-type ‘a‘a lava flow -

17. - Three relatively thin ‘a‘a flows in cross section flow cores clinker

18. Accretionary lava balls ~1.5 m diameter

19. - pahoehoe flows

20. - Flow field of pahoehoe “toes” (individual flow units) ~0.5 m

21. - Old pahoehoe flows in cliff section, Kaua‘i ~2 m

22. - pahoehoe issuing from a crack in a previous toe ~40 cm

23. - active pahoehoe toe ~20 cm

24. - Stretched vesicle walls on the skin of s-type pahoehoe ~10 cm

25. - The interior of an s-type (“spongy”) pahoehoe flow

26. - Folding of the plastic surface crust: ropy pahoehoe

27. Side view into an active lava tube

28. Master lava tubes can be many meters high and wide. Note that during a tube-fed eruption, the main tube is almost as long as the flow, but that afterwards it almost never drains completely.

29. Lava trees (~2 m high)

30. A forest of lava trees, partially buried by scoria

31. - ‘Olelo no‘eau involving lava (from M. K. Pukui; compiled by Ululani Makue) O kalākoluna, o ka pāhoehoe kolalo. The sun above, the lava below. Said of a journey in which the traveler suffers the heat of the sun above and the reflected heat from the lava below (i.e., a difficult trip or a difficult situation for which there are no easy solutions). Kīkēke ‘alā, uwēkamāmane. When the boulders clash, the māmane tree weeps. Meaning that when two people fight, those that are dear to them are the ones who suffer. PAU

32. Solidified dikes are exposed by erosion on old Hawaiian volcanoes

33. If a whole lot of dikes are exposed, it means that erosion has exposed the core of an old rift zone Here are a whole bunch of dikes in a roadcut near Windward Community College (unfortunately they’re now covered by a wall). Photo by F. McCoy

34. The axis of one of the Wai‘anae Volcano rift zones is exposed in the cliff at Kaneana. - - Makua cave Farrington Hwy.

35. Dike rock is usually more resistant to erosion than the lava flows that the dikes are cutting through. They end up standing above the more- eroded flows to form narrow blade-like ridges.