The federal government plans to increase the number of advanced earthquake monitors in the Hawaiian Islands within 18 months, the Pacific Tsunami Warning Center said yesterday.

The idea was not prompted by last week's earthquake off the Big Island, said Gerard Fryer, a geophysicist at the center, though the instruments would help keep track of such temblors.

Instead, pans to install 12 new "broadband seismometers" around the Islands were hatched after a 9.1-magnitude earthquake struck off the coast of Indonesia's Sumatra Island in December 2004, triggering a tsunami that killed more than 230,000 people.

Hawai'i has three broadband seismometers, Fryer said. One is on the Big Island and two are on O'ahu.

The National Oceanic and Atmospheric Administration, which operates the Tsunami Warning Center at 'Ewa Beach, is paying for them, but they will be operated in collaboration with the U.S. Geological Survey.

The new instruments will be located in fairly remote places, mostly on state or federal land, about a mile from the coastline.