San Benedicto Island, Revillagigedo Islands, Mexico
19.308 N, 110.807 W
summit elevation 332 m
Volcan Bacena is located on the southern part of Isla
San Benedicto, the third largest and most northeastern of the four Islas Revillagigedo of Mexico. The island is located about 220 nautical miles south of Cabo San Lucas, Baja California.
San Benedicto volcanism has progressed south along a narrow submarine ridge which extends over 20 miles north of the island. Crater Herrera, northeast
of Barcena, is the remnant of a large pyroclastic volcano, the cone of which has been eroded by waves.
The volcano is composed of a cinder cone with a base diameter of 700 m. The 1952 eruption was the first recorded historic pumice eruption in the eastern Pacific Ocean.
Volteadura Beach (591 m long) lies between Delta Lavico and a small lava flow SSE of Monticulo Cineritico. The beach is mainly composed of coarse sand- to pebble-size ash and lapilli. Banda Beach (832 m long) is located between the Delta Lavico and Crater Herrera.
The birth of Barcena was witnessed by the crew of the crew of the clipper M/V Challenger. The eruption began at 0745 hr on 1st August 1952, with the sudden emission of a white plume. A few minutes later a dark gray-black column of ash was ejected. The volcano began erupting violently as the M/V Challenger left the area. Volcanic bombs were ejected into the sea southwest of Monticulo Cineritico. The eruption plume reached 10,000 feet altitude. A tephra cone was built by the eruption, which extended the shoreline of Isla San Benedicto 274 m seaward between 1-11 August, 1952.
The most striking feature of the birth of Bacena volcano was the base surge. The horizontal spread of the eruption column increased more rapidly than the vertical rise. This resembled the base surge of an atomic explosion.
In September 1952 a dome formed in the crater. By 15th November, lava had half filled the 1200 ft wide, 700 ft deep crater.
On 8th December lava broke through the base of the cone and flowed into the sea, forming Delta Lavico. The eruption finished by March 1953.