Smithsonian Institution
Global Volcanism Network Bulletin v. 20, no. 9, September 1995

Parker (Philippines)  Crater lake overflow causes flooding; no
       volcanic activity

southern Mindanao, Philippines
6.07N, 124.54E; summit elev. 1,842 m

The overflow of Maughan Lake, the crater lake at Parker volcano,
followed heavy rains associated with a passing  typhoon and caused
flashflooding in NW-flank communities on 6 September. A team from
the Philippine Institute of Volcanology and Seismology (PHIVOLCS)
was dispatched to determine whether the overflow was caused by
volcanic activity. Although no volcanic alert was declared,
PHIVOLCS recommended that the crater area should be considered off-
limits because of instability of the crater walls. Fieldwork on 8-9
September revealed that the flood was channel-confined along the
NW-flank Alah River, which drains the crater lake, from 1,000 m
down to 540 m elevation (Barangay New Dumangas, T'boli, South
Cotabato Province). Below this point it was transformed into a
sheetwash. The floods killed more than 60 people, destroyed 300
homes and nine bridges, and displaced 50,000 people.

Aerial observations on 11 September indicated that two or three
landslides, indicated by escarpments, had occurred along the Alah
River prior to the crater lake outbreak. The total mass displaced
appears to have been sufficient to have dammed the upper reaches of
the river. The crater wall was well-vegetated and without landslide
scars, although underwater landslides may have contributed to the
rise and subsequent overflow of the lake. The overflow breached the
blocked river channel, sending an estimated ~10-15 x 10^6 m^3 of
lake water down the river, lowering the lake by 1 m. No turbidity
or color change was observed in the crater lake, indicating that
there had been no volcanic explosion. On 9-10 September PHIVOLCS
installed seismometers in T'boli, 12 km NW of the crater at 540 m
elevation, and at Tobolok, ~4 km NW of the crater at 1,300 m
elevation. No volcanic seismic events were recorded through 11

Parker is located ~30 km W of General Santos City in South Cotabato
Province. Little is known about the history of this volcano, which
has a 2-km-wide summit caldera. Preliminary investigations indicate
that an eruption attributed to Awu (Sangihe Islands, Indonesia) in
1640-41 may have actually been from Parker. That eruption caused
darkness over most of Mindanao.

Information Contacts: Ernesto G. Corpuz, Philippine Institute of
Volcanology and Seismology (PHIVOLCS), 5th & 6th Floors Hizon
Building, 29 Quezon Avenue, Quezon City, Philippines. (Email:
toti@x5.phivolcs.dost.; United Press International.

earthquakes was 252 at Station A, 2.3 km NW from Ponmachineshiri
Crater. The highest daily number of earthquakes, on 10 September,
was 19. On 13 September a volcanic tremor occurred for one minute