This was probably caused by magma movement near the surface, but there was no surface activity or eruption.
This presents a distinct hazard to the communities around it as well; for example, in the event of an eruption similar to the 1801 event, Kailua-Kona, which is 15 mi (24 km) from the volcano's summit, could be covered completely in a matter of hours.
These are summarized in the table below: Vent lava spatter and lava flows, cinders and tuff at Waha Pele.
Spatter cone erupted pahoehoe and ʻAʻā basalt lava flows.
Data collected showed that the lava flows there originated in shallow water 500 to 1,000 m (1,600 to 3,300 ft) deep, and that unlike similar slumps at other volcanoes, the slump at Hualālai formed gradually.
Haulālai is a known source for xenoliths, rock from the Earth's mantle that have been brought up in lava flows.
Hualālai is estimated to have risen above sea level about 300,000 years ago.
Despite maintaining a very low level of activity since its last eruption in 1801, Hualālai is still considered active, and is expected to erupt again some time within the next century.
Hualālai's structure is denoted by three rift zones: a well-developed one approximately 50° to the northwest, a moderately developed one to the southeast, and a poorly developed one trending northwards about 3 mi (5 km) east of the summit.
Much of the southern slope (above the modern town of Kailua-Kona) consists of lava flows covered by a layer of volcanic ash from 10 to 100 cm (4 to 39 in) thick.a, Hawaiian for "many-furrowed hill", a volcanic cone standing 372 m (1,220 ft) tall and measuring over 1.6 km (1 mi) in diameter.
It extends for 9 km (6 mi), and has a prominence of 275 m (902 ft), north of the summit at i.
The relative unpreparedness of the residents in the area caused by the lull in activity would worsen the consequences of such an event.
The area near the volcano has been inhabited for centuries by Hawaiian natives, dating back to before recorded history.