East Rift zone
Recently, this active site has experienced around 100 eruptions (Moore, R.) and the first one to ever occur here is estimated at half a million years ago, before it had ever reached the island rock (4). Along the caldera, past eruptions have left volcanic debris, such as cones and tuffs (Moore, R.), along the slope, as it descends to the sea. The reason for why the outpouring of lava flows, both aa and pahoehoe (4), moves South-East is due to the presence of the large mass of Mauna Loa. It comes into contact with this Kilauea volcano along the North side, and stops the movement of rock or intrusions in that direction, as seen in Figure 3. This leads to a build up of stress, resulting in parallel faults and largely displaced fissures, with offset on the scale of metres (Moore, R.)
Also seen in Figure 3, are the many dikes which rise up eastwardly (Swanson) from the underlying magma chamber situated below the rift zone (5). They reach metres wide, creating new ones towards the South, the youngest labelled #5 in Figure 3. According to the University of Hawaii Manoa, the Kilauea volcano has one of the greatest heat outputs worldwide, which is due to the high activity of the East Rift Zone (4). With the last eruption in 1961, it "may be overdue for its next [one]" (Moore, R.).
Southwest Rift zone
Additionally, both InSAR and GPS technologies have been used to measure and track the crustal inflation surrounding the main caldera and surrounding rift zones. The data recorded that over the past decade, inflation has occurred over an area which extends for 12km with a width of 8km (Myer, D. et al). Refer to the figure below to view vectors representing the magnitude and directions of displacement (in terms of velocity).
Kinematics of kilauea rift zones
The formation of rifts, and their extensional displacement is characterized by a relationship between stress and faults. There is a "high strain and stress changes in the host rocks" (Troise, C.) which causes slipping along the faults with earthquakes on the order of M>7. In these areas, the primary faulting is at a low angle, or rather they are thrust faults and can be either reverse or normal in orientation, however the former is dominant. Altogether, these properties can be used to "explain the main features of Kilauea [rift zone]" (Troise, C.).
Video: Lava flow at east rift zone (2010)
1: Moore, Richard B. "Volcanic Geology and Eruption Frequency, Lower East Rift Zone of Kilauea Volcano, Hawaii." Bulletin of Volcanology. 54.6 (1992): 475-483. Print.
2: Troise, C. "Stress Changes Associated with Volcanic Sources: Constraints on Kilauea Rift Dynamics." Journal of Volcanology and Geothermal Research. 109 (2001): 191-203. Print.
3: Myer, D, D Sandwell, B Brooks, J Foster, and M Shimada. "Inflation Along Kilauea's Southwest Rift Zone in 2006." Journal of Volcanology and Geothermal Research. 177.2 (2008): 418-424. Print.