TOKYO, Jan. 4 (Xinhua) -- The death toll from the massive earthquake in Japan climbed to 84 in the central Japanese prefecture of Ishikawa while the number of people unaccounted for surged to 179 as of 18:00 local time on Thursday, as a critical 72-hour window for search and rescue operations has closed.

A series of earthquakes of up to 7.6 magnitude struck the prefecture and its vicinity on Monday. The powerful main tremor, followed by hundreds of aftershocks, injured a total of 305 people in the prefecture, local authorities said.

Many were still believed to be trapped under rubble in the hard-hit coastal city of Wajima, where 48 deaths were confirmed so far, Kyodo News said.

The first 72 hours after earthquakes are especially critical for rescues because the prospects for survival greatly diminish after that, experts say.

However, miracles did happen as Japanese rescue workers pulled out a woman in her 80s from a collapsed house in Wajima City at around 4:28 p.m. local time, just over 72 hours after the major tremor hit the Noto Peninsula, noting that the woman was conscious and responsive.

The extent of the damage from the earthquake and the tsunami it triggered remains unclear. Rubble and severed roads added to challenges in search and rescue operations, three days after the disaster struck on New Year's Day.

Some roads have become impassable, leaving some areas cut off and without any help. According to Ishikawa prefecture, at least 750 people were cut off in 29 districts as of Thursday morning, public broadcaster NHK said.

Prime Minister Fumio Kishida earlier called for an "all-out effort" to save as many lives as possible during the first 72 hours following the disaster at a meeting of the emergency disaster response headquarters.

Ishikawa Governor Hiroshi Hase told a disaster management meeting that as of 4:00 p.m. local time, 72 hours after the quake, "the survival rate of those in need of rescue is said to drop precipitously."

The government plans to allocate roughly 4 billion yen (28 million U.S. dollars) from reserve funds to beef up its response while doubling the number of Self-Defense Forces members engaging in rescue operations and other efforts to 4,600.

With many running out of food and water supplies in affected areas, the Ministry of Land, Infrastructure, Transport and Tourism announced on Thursday that a transport ship carrying food and essential supplies was set to arrive at either Wajima port or Nanao port in Ishikawa prefecture by Friday evening.

The Ministry of Agriculture, Forestry and Fisheries said it will continue to provide food supplies to the quake-hit areas, after having sent about 240,000 meals with bread, rice and instant noodles, as well as 500 packages of powdered milk by Wednesday, at the request of Ishikawa prefecture.

The ministry said the supplies have already reached the relay point in the prefecture and will be delivered to shelters and other destinations, adding that they shipped 190,000 bottles of drinking water on Thursday.

Meanwhile, a Maritime Self-Defense Force transport ship has arrived off the coast of Wajima and unloaded heavy machinery that will be used for disaster cleanup work.

As of Thursday, nearly 95,000 households, suffered water outages in several parts of Ishikawa due to water pipe damage, and some 34,000 people have stayed at evacuation centers in Ishikawa, according to media reports.

The land ministry said that areas of at least 100 hectares in Ishikawa were flooded by tsunami waves following the earthquakes, and the true extent of the flooding will likely be larger.