Big Island, Hawaii, Part 3

This is the last of a three part article about the volcanoes of Big Island, Hawaii. In the first part, I discussed their background and explained some of the terms used to describe the lava that can been seen there. In the second, I discussed some of the highlights that my wife and I saw during our several trips to the island, including in October 2014. And in this part, I will continue to describe what we saw.

1. kipuka IMG_1844
Fig. 1. One of the kipukas (that is, untouchedby- lava areas of forest).

The abandoned lava cliff at Kalapana

This is a stretch of old cliff face that is now several hundred metres from the sea. It is located among the flows of February 1992 to October 2003, but the area was re-flooded with lava between 2007 and November 2013, when the ocean entry hereabouts was blocked. The site is just under 5km southwest of present-day Kalapana near Poupou, where the Royal Gardens lava flow reached the coast. The walk is well worth the effort for the variety of lava formations, the many tumuli or blisters of lava, and the coastal scenery along the present cliffs. We were guided here by Gary Sleik, who lives on the lava at Kalapana.

2. IMG_1896
Fig. 2. The first section of cliff face, with the lens-shaped tube blocked by cindery flow.

The cliffs are backed up by a small kipuka, which is an area that was left untouched, as the lava flowed around it and therefore is still a lush, well-forested island among the dark bare lava. There are several such fortunate stretches of original forest in the area. The first section of cliff face is a tale of its history – two major flows that came over this area in the distant past, including a lava tube between them, since filled in with an very cindery flow that came though the tube and over the surface. Behind this cliff, there are several windows down into lava tubes, which are mainly blocked up with subsequent flows and one may well lead to this lens-shaped opening. The base of the cliff is now buried by an unknown depth of fresher black pahoehoe lava. The detail of one episode can be seen in one small section, where the lower vesicular flow was several metres thick and formed slightly columnar shrinkage cracks through its depths, but also has a dark ropey lava surface. Above this, there is the clinkery a’a flow at the level of the lens-shaped tube.

3. layers of lava
Fig. 3. A small section of the cliff face, showing the junction between flows.

On the next section of cliff face, the thick basalt layers are more irregularly broken up and there is a cave entrance at the level of the new flow. This entrance is about half a metre high and little more than a metre wide. Around it, there are slump areas in the new lava, where molten lava was sucked down, perhaps into this cave or others. From the entrance, the cave had a drop of several metres onto fallen blocks and fresh flow. Although it is deep, it is not far across – the opposite wall can be seen with a good torch. It is an a’a flow above a much more columnar basalt face, with its top pediment several metres below the entrance level. Unfortunately, the drop to the floor of the cave is a long way in the dark, especially with no way to climb out. The mass of cobwebs across the entrance doesn’t help, either. However, it is possible to look down to the right and see the next level down in the cave – the floor drops steeply to a lower level, in a lava fall underground. There are interesting dribbles and fingers of lava around the cliff near the cave, such as several openings that contain miniature grottos of stalactites and small pillars of lava. Also, along the edge of the cliff, the remains of the former forest can clearly be seen. Tree moulds are also easily visible in the cliff face, with a complete coconut cast among them.

4. cave entrance IMG_1925
Fig. 4. The cave entrance, less than a metre high at the base of the cliff.

Moving further along this cliff line, there is a skylight down into a lava tube. Around ten meters deep, the walls seem to be comprised of mainly solid basalt blocks and there are two levels at which the lava flowed for extended periods. The floor and the base of the upper level have pahoehoe surfaces. There is reputedly an extensive network of such tubes in this area, one called the Cave of Refuge, which has a variety of legends attached to its historical uses. It seems that some are several hundred metres long and some are interconnected. Once again, it is difficult to explore without a known way out or the necessary equipment. The columnar nature of the thicker lava is seen in some of the deep cracks in the vicinity.

The cliff then changes entirely in its character. This location was once an ocean entry point, where the lava exited one or more of tubes and flowed over the cliff in a mass of fire-falls. They left innumerable wonderful flows and dribbles in great variety, caught in the act and frozen in a near-vertical face.

5. cave IMG_1913a
Fig. 5. Inside the cave, showing the columnar face opposite the entrance. The flow into the lower level is at lower right, under the columns.

Kapoho Cone and Green Lake Crater

Of course, the whole of Big Island Hawaii is made of lava and this corner of Puna District is no exception. From Kilauea to Kumukahi Cape runs the East Rift Zone, with a parallel graben (down-faulted section). There is thought to be no direct connection between the rift faults and the graben.

1. Map of the eruption area
Fig. 15. A map of the Kapoho eruption. Cape Kumukahi is the eastern-most point of Hawaii, extended by the a’a and pahoehoe lava floods of 1960.

There have also been several volcanic events in this area. The earliest one that has been dated with any accuracy is from about’ 400 years ago,’ when the Puʻu Kapoho cone formed during a phreatomagmatic (steam-powered) eruption. The hill doesn’t look to be particularly volcanic from the surrounding area, because it lacks the conical height and angle of slope of a true cinder cone (it is only 110m high). This was extremely explosive because of the amount of water present, which is a result of its very low height above sea level. This kind of activity formed a low, broad cone, with abundant fine particles that helped cement the ash and larger fragments and angular blocks together to form a volcanic tuff cone, which soon turned to the reddish brown of iron-rich lavas. Diamond Head, Punchbowl and Koko Head on Oahu are also tuff cones at a low elevation in Hawaii, but are much more famous than Kapoho.

2. Kapoho Hill, which erupted c1600 IMG_0980a
Fig. 16. A view across the a’a field to Kapoho Hill (Pu’u means hill), which erupted sometime in the first half of the seventeenth century, in a series of phreatomagmatic events from four fissures.

It may not appear to be especially volcanic at first, but it has a distinct rim on three sides and it is entered by the gap on the eastern flank, where the lava and pyroclastic materials flowed outwards. The track takes you up to a car park and recreation area. From here, it is possible to see down into the lake and upwards around the rim. Without contemporary accounts, it is not easy to build up a clear picture of the eruption around the 1600 AD, but there were seemingly four active vents erupting explosively, one of which produced the inner crater that began to collect water soon after the eruption ceased. This resulted in Green Lake and the water really is green – with algae. It is known to Hawaiians as Ka Wai a Pele.

3. Red-iron tuff buried by more recent lava flows IMG_1161aa
Fig. 17. Cross section of reddish tuff deposits blasted out during the very explosive, steam-driven eruption from four fissures. Now covered by more recent lavas.

Opinions differ as to whether this is on private or state land, but there is a gate and an admission charge of five dollars, which goes to local community causes, including the upkeep of the site. While we were visiting, the access from the rim down to the water was said to be closed because of damage caused by Hurricane Iselle, two months earlier. The water had reputedly been polluted by vehicles blown into it during the hurricane, although there was no sign of them or any oil on the surface – just a few damaged trees and forest debris in the lake. It is a very popular picnic spot and recreation ground for local people, and some swimmers were climbing up the path from the water when we arrived. Views down into the lake are restricted by the dense woods that fill the area, but there are glimpses of the lake from the rim.

4. Kapoho and Green Lake
Fig. 18. An aerial view of the Kapoho tuff cone, with Green Lake almost in the centre and the 1960 flow at bottom right. The almost circular shape of the crater is very clear, with the outflow coming down the middle of the picture.

We had a four-wheel drive rental car and were encouraged by the gate staff to drive to the top rim of the volcano, where there is additional parking and a picnic area. It is about a half-hour walk or five minute drive from the lake overlook. The view from the top is most worthwhile – right across this corner of the island, including all of the eruptive features from earlier and later times. Later eruptions very close by took place in 1840, 1923 (although with no surface lava), in February 1955 and January 1960.

A personal communication from the aerial photographer informs me that he, William Appleton, owns the land and he kindly gave permission to use the picture. He also added that recent thinking suggests that the crater and lake were formed only 350 years ago, rather than the 400 years, as traditionally suggested. There is apparently a proposal to build a geothermal power plant in the vicinity, although current thought is divided about whether the lake water is purely run-off or has a tidal connection (which could contravene groundwater pollution laws).

Tottering on the a’a lava at Kumukahi Lighthouse Point

A real disaster came to the small village of Kapoho, which was a place that lived by growing coffee, papayas and orchids. Early in 1960, there was a major eruption linked to Kilauea, from Puʻu Kapoho. It was one of a series of eruptions from the flank volcanoes of Kilauea. This was the last eruption in this immediate area and centred on a series of fissures just to the north of Kapoho and Green Lake. They are believed to have erupted from the same fissure system as Kapoho and are referred to as the Kapoho eruption, even though they didn’t come out of the actual Kapoho crater, where Green Lake is located. Lava spread eight or nine kilometres across Cape Kumukahi to the sea, extending the coast by an area of two square kilometres during 1960.

2 early view
Fig. 23. Dominating the town in the early days, the fire fountain produced masses of cinder, as well as lava.

When the summit eruption of Kilauea Iki ceased in December 1959, it was known that the magma chamber was more inflated than it had been at the start of the eruption, so it was no surprise when earthquake rumbles began further along the fault line of the East Rift Zone the following month, with over a thousand recorded on 12 January 1960. Overnight, large cracks opened in the ground in Pahoa and Kapoho towns, both of which are located on the rift line. By 8am, more large cracks opened up and lava fountains began along the main split about 300m from Kapoho, within the graben, rather than along the actual rift line. Within half an hour, lava was spurting up to 30m high, along a fissure of just under a kilometre in length, with flows of pahoehoe and a’a lava flooding away from the fissure. Before long, cinder and spatter cones were being formed as the fountaining increased and started to concentrate in particular points, all about eight kilometres from the sea. The largest of these was Pu’u Laimana, just north of the Kapoho Cone.

There was a period of phreatomagmatic activity, when saltwater from Warm Springs Resort came into contact with the magma, and large quantities of fine black ash were produced by extremely powerful and spectacular outbursts. These clouds and their contents reached as far away as Oahu and even Kauai – a distance of over 535km.

The layers of ash were buried by later lava flows. A huge pahoehoe flow moved smoothly at around 3kph, carrying rafts of crusted lava – known as slag (as in the mining and smelting industries). Later lava fountains were up to 60m high with explosive bursts. A lot of flame was seen from burning ohio trees and methane in buried forest litter. Methane fires erupted from the ground behind photographers, who were then close to the leading edge, forcing speedy retreats. Before long, the rich coffee, orchid and papaya fields were entombed under lava and ash, and a record number of properties were destroyed in one evening (over a hundred). Legally, the fire brigade was obliged to try to stem every single fire, though their hoses were clearly having no effect whatsoever. The town was largely burned out, and then submerged under lava or giant heaps of cinder and ash. Bulldozed ridges and dykes were ignored by the lava, which opened new fissures further west.

3 powerful blasts of steam_1
Fig. 24. As the lava flowed through Warm Springs Resort, the contact with the underground water source produced powerful steam blasts and clouds reaching thousands of metres into the air.

Activity intensified and the fountains were estimated at 350m for several days, and reaching 450m at times. Vast quantities of lava flowed towards the coast. The mainly pahoehoe flow carried huge slabs of former crust at an estimated 3kph, in enormous amounts over a three-kilometre wide front.

The underside of the slabs is generally either an extremely sharp ‘pluck’ surface, where the near-solid lava has dragged loosely across earlier rock; or a ‘drip’ surface, where the underside has still been molten, but lifted, which allowed the liquid lava to drip downwards into the gap below. Either form is extremely difficult to walk on, when the slabs have been jumbled up and turned over, or left jammed on edge.

6. Molten flowing Slabby lava (2)
Fig. 27. Fast-moving lava flows tumbled over obstructions in lava-falls, carrying large amounts of surface ‘slag’, which are rafts of crust from earlier solidifying areas.

Eventually, the flow began to diminish in power and the great fountains were lessening and sending out ‘soggy bombs’ rather than great heights of spatter, turning red as the temperature dropped and the volume decreased. Within a day or two, the fountaining was finished, but it took another two weeks for all the lava movement to cease. The slowly continuing lava gradually became cooler and the surface was changing into an a’a flow of ‘broken and crumbly’ blocks and cinders, carried along by the slowed-down more fluid lava beneath. This slowly built up to a wall of a’a lava four and a half a metre high, and travelling at less than a half a kilometre an hour across the Kumukahi Cape.

The a’a flow is the one that finally covered most of the area, overrunning the coastguard and lighthouse stations. However, it skirted round the lighthouse itself, leaving it untouched with six metres to spare on three sides. This lava is very broken up a’a, with large and small blocks, and slabs and crust sections. And there, amongst it, stands the open girder-work of the lighthouse – untouched.

7. In the making IMG_4986
Fig. 28. Slab lava being formed from the rafts of crust that were carried along by the still molten lava beneath. My thanks to Darlene Cripps and Gary Sleik for this picture.

The whole surface of the a’a flow is very rough, but stable. The blocks and slabs cooled while still stuck together, as opposed to a mass of loose cindery material, which can be very unstable. If the face of an a’a flow becomes very solidly fixed, it holds back the continuing flow of molten lava behind it. This will cause upward pressure beneath the crusted surface. One way to release the pressure is for the lava to squeeze out between hard slabs and blocks. This can frequently produce an effect like toothpaste being squeezed out of a tube, as the lava exudes onto the surface and is pushed away. The surface flow will often retain the grooved nature of the gap through which it came, making a series of fluted lines along the surface.

Here and there among the tangled masses of a’a blocks and slabs, these flatter areas survive where the ‘toothpaste’ areas of flow have not broken up – presumable among the last active phases of the eruption. Like roadways through the broken jumble, they have longitudinal grooves that reflect the edges of the crack they were forced out of. Some of them also have ‘pressure pulse’ lines across them, which have something of the appearance of a roughly-ploughed field. They indicate that the lava was squeezed out in pulses, perhaps half a metre of forward movement across a nine-metre wide front. They occur at many points throughout the a’a flow, including in the vicinity of the lighthouse, and not just close to the original crater. This implies that the lava travelled a considerable distance under the main surface before it solidified, and then surfaced wherever it was able to force its way upwards.

Similar at first sight to the ‘toothpaste’ roadways are flat runs of lava, which were surface flows of pahoehoe lava, just at the stage where it ran out of strength and heat. However, the pahoehoe flows have curved wrinkles spreading across them and extending back along the edges towards the source of the lava; whereas the toothpaste flows have grooved lines along the length of them, except for the ‘pulse’ lines cutting across the flow, which are usually straight, rather than curved.

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Dr Trevor Watts (UK)

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