31 July 2000
TWO VOLCANOLOGISTS KILLED ON INDONESIA'S SEMERU

A minor explosive eruption at the summit crater of Semeru volcano on the Indonesian island of Java killed two Indonesian volcanologists and injured three American and one Israeli volcanologists on 27 July. Press sources did not give the names of the two Indonesiand who died, but the names of the injured were released. Among the Americans is Lee Siebert of the Smithsonian Institution in Washington, D.C., specialized on volcanic debris avalanches and co-author of world-famed books like "Volcanoes of the World". The other two Americans are Paul Kimberly and Mike Ramsey, of which the earlier received somewhat heavier injuries and had to be brought to a hospital in Singapore. Bad weather prevented rescue teams from reaching the dead and injured for one day, and the corpses of the two dead Indonesians could be retrieved only on 31 July.
Semeru is one of the most persistently active volcanoes of the world. Minor explosive eruptions occur frequently at its summit crater, some being accompanied by pyroclastic flows. However, it appears that the scientists at the were hit by flying rock fragments. In recent years, almost all fatalities related to volcanic activity have occurred in similar manner - simply because people came too close to active craters. In all cases the lethal eruptive events were very small on a geological scale. The most recent case of volcanologists killed by an eruption was in March 1993, when two Ecuadorian volcanologists were killed by a small phreatic explosion at Guagua Pichincha volcano in their home country.
In Japan, geophysical unrest has continued at the volcanic island of Miyakejima. Two strong earthquakes (measuring 5.4 and 6.2 on the Richter scale) shook the island on 30 July, causing landslides and minor damage, and injuring one person. The volcano on the island remained quiet. In the first half of July, the summit crater of Oyama volcano, the central peak of the island, had collapsed to form a small caldera more than 400 m deep. This was accompanied by spectacular emissions of gray ash, whose volume was estimated at about 10 million cubic meters. Japanese volcanologists observed several episodes of deflation alternating with inflating during that period; however no magma appears to have come close to the surface. Tens of thousands of minor and about a dozen larger earthquakes have shaken Miyakejima and neighboring islands since late June, and a possible submarine eruption occurred off the W side of Miyakejima on 27 June. Many residents of the island have left their homes. Scientists are expecting further earthquakes in the area.
In Chile, two volcanoes erupted in early and mid July: Copahue volcano, in the central area of the country, and Làscar, which lies much further to the north. Both eruptions were quite spectacular and caused ash falls to the east, in neighboring Argentina. While the Làscar eruption was apparently one single explosive event, the eruptions at Copahue were more prolonged, and Chilean volcanologists described them as the most intense ever observed at that volcano.
On the island of Réunion in the Indian Ocean, Piton de la Fournaise volcano was in eruption from 23 June to 30 July. Lava flowed to the east from a new crater, around which a large cone was built by mild lava fountaining and Strombolian activity. This cone was named Piton P�rv�di. This is the longest eruption at this volcano since the long-lived Piton Kapor eruption in March-September 1998. Three shorter eruptions had occurred in July and September 1999, and February-March 2000.

15 July 2000
MORE ERUPTIONS ON MIYAKEJIMA

The summit crater of Oyama volcano on the Japanese island of Miyakejima has been the site of further explosive (probably phreatic) eruptions on 14 and 15 July, which appear to have been associated with ongoing episodic subsidence in the summit area of the volcano. The most recent ash emissions were much stronger than that of 8 July, when collapse occurred for the first time, triggering the venting of lithic ash. Japanese television showed footage of billowing dark gray ash plumes which are strikingly similar to those emitted at Usu volcano (on the Japanese island of Hokkaido) earlier this year. The ash was blown over the northern sector of the island where it left a deposit which appears quite voluminous on press photos; some Japanese web sites dedicated to the Miyakejima crisis show photos of lithic blocks up to 20 cm in diameter, which created impact craters. Some residents of the affected area were evacuated.
The Oyama subsidence with the associated ash emissions occurred within a framework of much more widespread geophysical unrest, affecting the northern part of the Izu island chain within which Miyakejima is located. Intense seismic activity has affected that area since the beginning of volcanic unrest on Miyakejima in late June, including several earthquakes with magnitudes above 6 on the Richter scale. The latest strong shock with its epicenter near the small islands of Kozushima and Niijima (located to the NNW of Miyakejima) occurred on 15 July and triggered numerous rockfalls on these islands already affected by similar events in the past three weeks. Press sources reported that 8 people were injured.
On the Chile-Argentina border, eruptive activity is continuing since late June at Copahue volcano. Thirteen explosive ash emissions were observed since 14 July in the latest spasm of activity, which followed several days of minor activity. The eruption column reportedly rose up to 5 km high, and ash fell up to 60 km away to the E in Argentina. Chilean volcanologists remarked that the eruption is the most vigorous known of Copahue which last erupted in 1992.
Explosive volcanism has also been reported in the past few days from Guagua Pichincha volcano, Ecuador, where a portion of a lava dome formed several months ago failed, and at Popocatépetl volcano in Mexico.

9 July 2000
OYAMA ON MIYAKEJIMA ERUPTS; NUMEROUS EARTHQUAKES

On the Japanese island of Miyakejima, a short-lived, small eruption occurred on the late afternoon of 8 July at the summit crater of Oyama volcano. This event consisted of a single pulse of gas and ash emission, and all ejecta appear to be old lithic material. This indicates that no fresh magma has been involved in the event. Aerial photographs taken the morning after show that the entire area of the summit crater - which actually consists of a miniature caldera with a small central cone formed in 1940 - has subsided notably. The ash emission may have been caused by the subsidence, which in turn may be a result of magma withdrawing at depth. Magma evidently intruded into the volcano on 26-27 June but did not reach the surface on the island; an area of bubbling and steaming water was discovered on 27 June off the W coast of the island. So far it is not clear whether this was the effect of a small eruption on the submarine slope of the volcano, or if it was only caused by submarine gas emissions from a fracture caused by magmatic intrusion.

The ash emission at Oyama was followed a few hours later by a magnitude 6 earthquake, whose epicenter lay near the volcanic island of Kozushima, NW of Miyakejima. On that island numerous landslides occurred. During the past 10 days, the area between Kozushima and Miyakejima has been shaken by more than 30,000 earthquakes, some of which were quite powerful. The strongest earthquake, with a magnitude of 6.4, occurred on 1 July, causing numerous landslides on Kozushima. One man was buried in his car and killed by one of the landslides. About half of the population of the island was evacuated because more earthquakes were expected. The situation at the Izu islands became even more difficult in the past few days due to the passage of a typhoon, which had caused damage in the Philippines before and swept over Japan and Taiwan, causing deaths and destruction.
On Miyakejima, about 2000 residents had been evacuated in late June because of the fear of an impending eruption; they were later allowed to return home. The single ash emission from Oyama on 8 July is not interpreted as related to new magma movement towards the surface, and residents were only advised to keep an eye on the volcano, since it could not be totally excluded that it will still erupt.

27 June 2000
MIYAKEJIMA ERUPTS BELOW SEA LEVEL; EVACUATIONS

Following a dramatic increase in seismic activity on late 26 June, residents of the southwestern part of the small volcanic island of Miyakejima, located in the Pacific about 200 km SSW of Tokyo in Japan, were ordered to evacuate because it was feared that an eruption was imminent on the island. Furthermore ground cracking, an increase of the ground temperature, and a small landslide (possibly triggered by the seismic activity) were detected. Volcanologists supposed that the eruption could occur on the W flank of Oyama, the central cone of the volcano that forms the island. Through the night of 26-27 June, about 2500 residents were evacuated from areas believed to be at risk, some to the N part of the island, and others were brought by ships to the mainland of Honshu, the largest of the four main islands of Japan.
On the morning of 27 June, the volcano apparently became active. However, rather than erupting somewhere on the island, it did so on the submarine W flank, about 1.8 km from the W coast. Discolored sea water and steaming was observed at that site, both from a ship passing nearby and from airplanes flying over the area. Scientists voiced concern that more eruptive vents might open closer to the island or at the coast and produce violent phreatomagmatic explosions, caused by the contact of magma with sea water.
Miyakejima is the second largest of the Izu islands that extend from the Bay of Tokyo to the S (the largest of these islands is Izu-Oshima, with its famous volcano Mihara) and has a long record of historical eruptions. During the 20th century there were three eruptions, in 1940, 1962 (both in the same area on the NE flank) and 1983 (on the SW flank). All three caused extensive damage, and in the case of the 1940 eruption 11 people were killed. Lava flows of the 1983 eruption destroyed one village almost entirely, while many other buildings were damaged by heavy tephra falls.
Miyakejima is the second volcano in Japan to force evacuations this year. In late March and early April, Usu on the northern island of Hokkaido began a new phase of phreatic and phreatomagmatic eruptions accompanied by significant ground uplift. Small phreatic eruptions are continuing to the present day. Several buildings have been damaged by the fall of lithic blocks and by fracturing of the ground.

During the past few weeks several other volcanoes had significant eruptions. On 30 May an eruption started in the summit area of Mount Cameroon, following a series of earth tremors. A lava flow advanced several kilometers, approaching to the village of Bokwango, but by mid June the speed of the lava flow slowed significantly, and a few days later it seems that the activity ended. Mount Cameroon had last erupted in April-May 1999 when a voluminous lava flow stopped only a few hundred meters from the Atlantic coast.
On 23 June a new effusive eruption began on the SE flank of Piton de la Fournaise on the island of Réunion in the Indian Ocean, emitting lava flows to the E; one flow rapidly reached a length of 5 km. This eruption, which came only three months after the latest eruption of that volcano, was preceded by vigorous seismicity, and scientists had warned of an imminent eruption. So far the eruption does not present any hazard to inhabited areas on the island.

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Copyright © Boris Behncke, "Italy's Volcanoes: The Cradle of Volcanology"