The eruption of Kilauea is 24 years old, and while erratic in some ways, it seems to follow patterns.

The events of the past four days — the flurry of earthquake activity, magma migrating underground, the subsiding of the Pu'u 'O'o eruption — are similar to previous events on the volcano.

Here is a history of the activity:

1983: Kilauea's current eruption started on Jan. 3, 1983, with a series of fissures several miles east of the Kilauea Caldera on what's called the east rift zone. The eruption eventually centered on Pu'u 'O'o.

1986: The eruption moved down the slope away from the Kilauea summit. For more than five years, lava poured from Kupaianaha, creating an expansive shield structure there. During this period, the lava wiped out the communities of Kalapana, Royal Gardens and Kapa'ahu, all effectively destroyed by 1990.

1991-92: Starting in November 1991, fissures erupted between Kupaianaha and Pu'u 'O'o, and within months, Kupaianaha stopped erupting. Activity moved back to Pu'u 'O'o by early 1992. For most of the time since then, lava has flowed from the cone there, or from nearby vents.

1997: In January 1997, lava production at the Pu'u 'O'o site dropped, the crater floor collapsed, and one side of the cone wall fell down. Meanwhile, fissures opened and erupted upslope near Napau Crater. But this activity lasted only about a day, and for three weeks afterward, there was no fresh lava on Kilauea's flanks. Then Pu'u 'O'o started up again.

1999: A swarm of earthquakes and broad deflation were believed to accompany a magma movement into the upper east rift zone — similar to what has been happening in recent days. The diverting of magma into underground fractures is believed responsible for an 11-day break in the eruption. Then the magma flow to Pu'u 'O'o reasserted itself and the eruption there started up again.

2007: The current activity again seems to suggest some kind of blocking of the flow of magma feeding Pu'u 'O'o. Instead, magma appeared Sunday and yesterday to be squeezing into fractures between one and two miles deep between the Pauahi and Makaopuhi craters. As of late yesterday afternoon, no lava had reached the surface near this site.

4-DAY KILAUEA TIMELINE:

Yesterday, late report:

Pu'u 'O'o eruption seems to have stopped. Small amounts of lava still drip into the sea, but no significant flow.

Geologists tracking a few new earthquakes to the east, but most of the magma seems to still be entering the underground area between Pauahi and Makaopuhi craters.
Widening across the rift zone near Makaopuhi now up to 28 inches.

Eruption still possible, said Jim Kauahikaua, head of Hawaiian Volcano Observatory.

Yesterday, 8 a.m.:

Earthquake activity drops to fewer than 10 temblors per hour, but there is a strong tremor, suggesting magma continues to move underground.

The widening at the area of greatest earthquake activity has slowed. Pu'u 'O'o continues to deflate. It is steaming but glow is no longer visible. Observers were to inspect it yesterday morning.

Chain of Craters Road remains closed, along with trails to east rift zone. Crater Rim Drive reopens.

Yesterday, 4 a.m.:

Widening across the rift zone near Makaopuhi now up to 15 inches.

Pu'u 'O'o deflation continues, and glow from the eruption now intermittent; many rockfalls and collapses in the vent area.

Teams scheduled to head into the earthquake area to see what changes have occurred.

Yesterday, just after midnight:

Earthquake rate slowing to 10 to 15 small temblors per hour, between Pauahi and Makaopuhi and about 1.5 miles deep. The spread across the Makaopuhi area is now near 8 inches.

Pu'u 'O'o deflating steadily. The glow from the center of the eruption appears to be dimming.

Strong tremor continues under summit area.

Sunday, late report:

Focus of underground activity appears to be moving downrift, away from the Chain of Craters Road and toward the Makaopuhi Crater. Pumping of magma into the area is spreading the top of the rift zone apart. The area appears to have widened about 4 inches between 5 a.m. and 2 p.m.

Eruption continues at Pu'u 'O'o, but crater floor has collapsed around vents and East Pond lava level dropping.

Geologists say the activity up-slope may be reducing magma flow to the eruption.
National park evacuates people from Chain of Craters Road area, and evacuates its herd of working horses and mules from a pasture near the upper east rift zone.

Sunday, early report:

A dense swarm of shallow quakes — at times 100 an hour — start at 2:15 a.m. about a mile southwest of Mauna Ulu, about 1.5 miles deep. Some strong enough to be felt by residents of the Volcano region. Ten of them exceeded magnitude 3.0.

Significant changes in tilt near the quake area. Kilauea summit deflating.

Geologists say the event may be molten rock moving into the shallow region. The center of activity is within a mile of the Chain of Craters Road, and cracks begin to appear in the road near the Mauna Ulu turnoff.

Quakes continue through morning at about one per minute.

Eruption continuing at Pu'u 'O'o, but tilt meter now recording weak deflation.

Chain of Craters Road closed. Crater Rim Drive closed between Jaggar Museum and Thurston Lava Tube. Visitors being evacuated.

Saturday:

Small shallow earthquakes continue south of Halema'uma'u. Seismic tremor low.
Two small deflations near the Kilauea summit, but no accompanying change in seismic activity.

At Pu'u 'O'o, inflation slowing.

Friday:

A flurry of earthquakes under and south of Halema'uma'u. Seismic tremor low. Very slow inflation across summit. Pu'u 'O'o inflation normal.

Source: Hawaiian Volcano Observatory, Hawai'i Volcanoes National Park

Reach Jan TenBruggencate at jant@honoluluadvertiser.com.