Bul le tin of the Global Vol can ism Net work Vol ume 28, Num ber 9, September 2003 Kilauea (USA) Active surface lava flows from June through mid-Oc tober ....................2 Katmai (USA) Strong winds re suspend old ash depos its, causing a large plume and distant ashfall ......3 Anatahan (Mariana Is lands) Very low seis micity with no ash emissions; geo thermal ac tivity in the crater ...4 Mayon (Phil ip pines) El e vated sul fur-di ox ide flux af ter mid-Sep tem ber; crater glow in Oc to ber ........4 Karangetang (In do ne sia) Ash explo sions and lava av a lanches in July; overall activ ity level decline s .....5 Dukono (In do ne sia) Ash explo sions in late July through Sep tem ber gen erate plumes up to 250 m high.....6 Gamalama (In do ne sia) Several small ash explo sions and gas emission through late Sep tem ber ........6 Tongkoko (In do ne sia) Vol ca nic earth quakes dur ing Oc to ber 2002-Jan u ary 2003 ...............6 Tandikat (In do ne sia) Brief ep i sode of in creased seis mic ity dur ing Jan u ary-Feb ru ary 2002 ..........7 Dieng (In do ne sia) One shallow volca nic earthquake and a gas plume in early August .............7 Semeru (In do ne sia) Fre quent ash ex plo sions con tinue through Sep tem ber ...................7 Manam (Pa pua New Guinea) Minor ashfall from Main Crater activ ity dur ing May ...............8 Pago (Pa pua New Guinea) Minor seismic ity and va por emissions ; no lava effu sion as of 22 May........8 Ulawun (Pa pua New Guinea) White vapor emissions from the main crater; offshore effer ves cence.......9 Rabaul (Pa pua New Guinea) Fre quent ash plumes from March through early Oc tober 2003 ..........9 Lam ing ton (Pa pua New Guinea) High-frequency earth quakes began in early July ..............10 Ambrym (Vanuatu) Lava visi ble in six vents during Septem ber; lava lake activ ity and ash emissions .....11 Momotombo (Nic a ra gua) Some seis mic swarms and tornillos; stable fumarole tem pera tures .........12 Concpecíon (Nic a ra gua) Three peri ods of ele vate d seismic ity be tween June 2002 and August 2003......13 Arenal (Costa Rica) Pyroclastic-flow sequence down the N and NE flanks on 5 Septem ber ..........14 Poás (Costa Rica) Hy dro ther mally ac tive re pose con tin ues through 2002 ...................15 Barva (Costa Rica) Two crater lakes vis ited in De cem ber 2002.........................18 Nyamuragira (DR Congo) Long-period earthquakes and swarms in July 2003 ................18 Nyiragongo (DR Congo) Con tin u ing lava lake ac tiv ity through mid-Au gust ..................19 Piton de la Fournaise (In dian Ocean) Seis mic cri sis and a new SSW-flank fissure on 30 Septem ber .....19 Edi tors: Ed ward Venzke, Rick Wun derman, Devra Wexler, and Gari May berry Vol un teer Staff: Rob ert An drews, Don Gruber, Dave Charvonia, Jacquelyn Gluck, and Ste phen Bentley Global Vol canism Program · National Museum of Natu ral His tory, Room E- 421 · Washing ton, DC 20560- 0119 · USA Tele phone: (202) 357- 1511 · Fax: (202) 357- 2476 · Email: gvn@vol cano.si.edu · URL: http://www.vol cano.si.edu/ Subscrip tions are provided by the Ameri can Geo physical Un ion (see the box on the last page for details). Data are prelimi nary and sub ject to change; contact the original source or the Global Volcan ism Program bef ore using. 2 Kilauea Smithsonian Institution — Bulletin of the Global from Pu`u `O`o and Kupaianaha. The area of recent lava Kilauea flows on the W side of the flow-field has been desig nate d the Mother’s Day flow, which began erupt ing on 12 May Ha waii, USA 2002 and conti n ues to the present (figure 2). Through Sep- 19.425°N, 155.292°W; sum mit elev. 1,222 m All times are lo cal (= UTC - 10 hours) During 2003, lava from Kilauea conti n ued to flow down the S flanks and into the ocean at several points. The Mother’s Day flow, which began erupt ing from Pu`u `O`o on 12 May 2003, rem ained acti ve. Seism icit y gen erall y per - sisted at norm al (background) lev els. A recent report from the U.S. Geolog i cal Survey, edit ed by Heliker, Swanson, and Takahashi (2003) de scribed the nearly uninterupted Pu`u `O`o-Kupaianaha erupti on that started 3 Janu ary 1983 and con tin ues to day. Lava flows. Lava en tered the sea mainly at the Figure 1. Map of se lected defor m ation sta tions at Kilauea, 2003. Cour tesy Highcastle ocean en try during 11-17 June and surface lava of HVO. flows were visi ble on the coastal flat and Pulama pali during June and July 2003. However, no lava flowed into the sea during the later half of July and into early Au gust. Defla tion that began on 8 Au- gust amounted to ~ 1.8 mrad at the Uwekahuna (UWEV) tiltmeter and ~ 4 mrad at the Pu`u `O`o tiltmeter, both lo cated near the Kilauea sum mit (figure 1). The de fla tion was ac com pa nied by a drop in the level of lava in a lava tube, as seen by field workers at mid day. In fla tion be gan later that day at 1928, and in ~ 3.5 hours ~ 3.5 mrad of in fla tion was re- corded at Uwekahuna and ~ 6 mrad at Pu`u `O`o. A lava break out occurred on 9 Au gust be tween 0200 and 0300, ~ 1.3 km SE of the cen ter of the Pu`u `O`o cone. A very large sheet flow emerged from the up-tube side of a root less shield formed on 21 Jan u ary. Observ ers saw a lava stream up to 40 m wide. By 0600 the flow covered ~ 5.2 hectares (0.052 km2). Later in Au gust and into Sep- tem ber, sur face lava flows were vis i ble on Kilauea’s coastal flat, in some areas flowing to within 500 m of the sea. On 2 Octo ber lava be gan to flow westward af ter fill ing West Gap Pit on the W flank of Pu`u `O`o cone. Fairly vig or ous spat ter ing was vis i ble in the pit, but decrea sed to only spo- radic bursts later in the day. The flow ap peared to have stopped by 4 Octo ber when no glow was ob- served com ing from the pit. Figure 2. Map se quence showing Mother’s Day lava flows that began on 12 May 2002 (darkest shade) from the Lava flows have erupted from Pu`u `O`o cone at Kilauea as of 21 May 2002, 25 Novem ber 2002, 16 May 2003, and 10 Octo ber 2003. Modi fied 1983 through 10 Oc tober 2003 from origi nal maps cre ated by the USGS Ha wai ian Vol cano Ob ser va tory. Volcanism Network, Volume 28, Number 9, September 2003 Katmai 3 tem ber and into early Octo ber, lava was mov ing along the E Kilauea Volcano, Ha waii: The first 20 years: U.S. Geo log i- and W sides of the Mother’s Day flow. The E-side lava cal Survey Profes siona l Pa per 1676, Den ver, CO. (menti oned previ ously as the 9 August breakout) came In for ma tion Con tact: Ha wai ian Vol cano Ob ser va tory from the 9 August root less shield, it self fed by the main (HVO), U.S. Geo log i cal Sur vey, Ha waii Vol ca noes Na- Mother’s Day tube from Pu`u `O`o. The W-side lava, tional Park, P.O. Box 51, Hilo, HI 96718, USA (URL: known as the Kohola arm of the Mother’s Day flow, http://hvo.wr.usgs.gov; Email: branched off the tube system below the root less shield. In [email protected]). early Oc tober, the E-side flow stopped mov ing, the W-side flow died back to a trickle, and the rootles s shield gained prom inence . By 16 Octo ber, however, the shield had partly collaps ed, leaving sev eral drained perched ponds. Up- Katmai stream from the shield, many horni tos and small flows formed over the Mother’s Day tube. Alaska Pen in sula, USA Geo phys i cal ac tiv ity. During the second half of June 58.280°N, 154.963°W; sum mit elev. 2,047 m and into August 2003, seism icit y at the sum mit was at mod - er ate-to-high lev els, with many small, low-fre quency earth - Accord ing to the Nati onal Weather Service , strong quakes occur ring at shallow depths be neath the sum mit cal - winds in the Katmai area on 21 Septem ber 2003 picked up dera at a rate of about 1-2 per minute. Lit tle or no vol canic old, loose vol canic ash and carrie d it E. Reports of minor tremor accom pa nied the swarm at the caldera, how ever. ashfall were re ported from Kodiak Island, ~ 100 km from Volca nic tremor at Pu`u `O`o rem ained at mod erate -to-high Katmai.