SYDNEY/WELLINGTON, March 5 (Reuters) - Strong aftershocks rocked Papua New Guinea's remote and rugged highlands on Monday, a week after the largest quake to hit the region in almost a century killed at least 31 people.
Three aftershocks stronger than magnitude 5 shook the mountainous Southern Highlands, about 600 km (370 miles) northwest of the capital Port Moresby early on Monday, the U.S. Geological Survey said, including a shallow magnitude 6 quake.
Papua New Guinea's national disaster center could not immediately be reached by telephone.
The strong tremors hit a region already badly damaged by the magnitude 7.5 quake that struck on Feb. 26, triggering landslides, flattening buildings and closing oil and gas operations.
At least 13 people were killed when hamlets nearest the epicenter were buried, while most of the other casualties were in the provincial capital of Mendi and the township of Tari, officials told Reuters.
Aid agencies have said nearly 150,000 people remain in urgent need of emergency supplies following that quake as damaged roads and landslides hampered the delivery of aid to isolated communities.
RELATED: Natural Disasters of 2017
Natural Disasters of 2017
Natural Disasters of 2017
Residents wade through flood waters from Tropical Storm Harvey in Beaumont Place, Houston, Texas, U.S., August 28, 2017. Jonathan Bachman: "It was my first day covering Hurricane Harvey. I only made it 500 yards into Houston when I came across a staging area where ordinary people were conducting water rescues in the Beaumont Place neighbourhood of Houston, TX.ï¿½In addition to the rescues, residents were able to walk against the current down a long road which is seen in the image. At first I went out on a boat with a couple from Louisiana to help and document several rescues. When we got back, I looked down the road and saw an almost perfect line of residents making the long walk to the staging area. I intentionally moved to a position so I could photograph them in a way that would convey the magnitude of this storm. I wanted to communicate that it was a never-ending line of residents struggling to get to safety and it would go on for days. Harvey was a very difficult and emotionally taxing assignment. My first instinct was to put down the camera and help. It is always hard to come to the realisation that I am most helpful when I am taking pictures.ï¿½As an observer of suffering you have to believe that your images can make a difference." REUTERS/Jonathan Bachman/File photo SEARCH "POY STORY" FOR THIS STORY. SEARCH "REUTERS POY" FOR ALL BEST OF 2017 PACKAGES. TPX IMAGES OF THE DAY.
Firefighter tackle a wildfire close to the village of Pucarica in Abrantes on August 10, 2017.
Nearly 3,000 firefighters battled 80 wildfires raging across Portugal civil protection officials said, as the return of scorching heat put an end to the respite after a spate of blazes. Some 650 firefighters backed by nine water-dropping aircraft and over 200 vehicles were at the scene of the biggest blaze in a forest near the central town of Abrantes. / AFP PHOTO / PATRICIA DE MELO MOREIRA (Photo credit should read PATRICIA DE MELO MOREIRA/AFP/Getty Images)
TOPSHOT - People leave San Ramon in a car taking their horse by the reins after a forest fire devastated the nearby town of Santa Olga, 240 kilometres south of Santiago, on January 26, 2017.
Six people -- among them four firefighters and two police -- have now been killed battling vast forest fires in central Chile, officials said Wednesday. Multiple blazes have ravaged 238,000 hectares (588,000 acres) and are growing, the National Forestry Corporation said in a statement. / AFP / Pablo VERA (Photo credit should read PABLO VERA/AFP/Getty Images)
A man rides his bicycle through a damaged road in Toa Alta, west of San Juan, Puerto Rico, on September 24, 2017 following the passage of Hurricane Maria. / AFP PHOTO / Ricardo ARDUENGO (Photo credit should read RICARDO ARDUENGO/AFP/Getty Images)
KARO, INDONESIA, OCTOBER 14, 2017: Sinabung volcano spews molten lava with lightening storm during eruption in hight alert status from Karo, North Sumatra province, Indonesia on October 14, 2017.
PHOTOGRAPH BY Sutanta Aditya / Barcroft Images (Photo credit should read Sutanta Aditya / Barcroft Images / Barcroft Media via Getty Images)
A woman and a child get rescued after a massive landslide and flood in the Huachipa district of Lima, Peru March 17, 2017. REUTERS/Guadalupe Pardo
Wildfires burn along the Twelve Apostles area of Table Mountain in Cape Town, South Africa, October 13, 2017. REUTERS/Mike Hutchings
A firefighter views a collapsed coastal house after Hurricane Irma passed the area in Vilano Beach, Florida, U.S. September 11, 2017. St Johns County Fire Rescue/Handout via REUTERS. ATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY TPX IMAGES OF THE DAY
SANTA ROSA, CA - NOVEMBER 5: The aftermath of a firestorm that began in Napa Valley's Calistoga, destroying thousands of homes in the Coffey Park, Fountaingrove, Larkfield, and Mark West Estates neighborhoods, is viewed from this aerial photo taken over Fountaingrove on November 5, 2017, in Santa Rosa, California. Officials are calling it the most destructive wildfire in the State's history, the Tubbs Fire roared through forested hillsides before descending into densely populated neighborhoods, destroying more than 6,000 homes, out buildings, and businesses, resulting in an estimated $3 billion in damage, 24 deaths, and leaving thousands homeless. (Photo by George Rose/Getty Images)
TOPSHOT - The picture shows an aerial view of a flooded area in Asakura City, Fukuoka prefecture on July 6, 2017.
At least two people have been killed and 18 others are missing in huge floods that are surging through southern Japan, with authorities warning hundreds of thousands of people to flee. / AFP PHOTO / JIJI PRESS / STR / Japan OUT (Photo credit should read STR/AFP/Getty Images)
Firefighters work to put out a forest fire near Bouca, in central Portugal, June 18, 2017. REUTERS/Rafael Marchante TPX IMAGES OF THE DAY
TOPSHOT - A wave breaks against a pier and a lighthouse as storm Ana smashes into France in Cassis on December 11, 2017, southeastern France. / AFP PHOTO / BORIS HORVAT (Photo credit should read BORIS HORVAT/AFP/Getty Images)
TOPSHOT - View from the Comala community, Colima State, Mexico, on January 19, 2017 of the Volcano of Fire in eruption.
The colima volcano is one of the most active in Mexico and in the last days its activity has intensified. / AFP / SERGIO VELASCO GARCIA (Photo credit should read SERGIO VELASCO GARCIA/AFP/Getty Images)
TOPSHOT - Indonesian rescuers search for survivors after a wall of mud slammed onto houses from a hillside after heavy rainfall in Ponorogo district, East Java on April 2, 2017.
At least one person was killed and 28 are feared buried after a landslide struck Indonesia, the national disaster agency said on April 1. / AFP PHOTO / JUNI KRISWANTO (Photo credit should read JUNI KRISWANTO/AFP/Getty Images)
Soldiers stand guard a few metres away from the Sensacion hotel which collapsed with the powerful earthquake that struck Mexico overnight, in Matias Romero, Oaxaca State, on September 8, 2017.
Mexico's most powerful earthquake in a century killed at least 35 people, officials said Friday, after it struck the Pacific coast, wrecking homes and sending families fleeing into the streets. / AFP PHOTO / VICTORIA RAZO (Photo credit should read VICTORIA RAZO/AFP/Getty Images)
TOPSHOT - Picture released on March 12, 2017 by Aton Chile shows firefighters working to put out a forest fire in Valparaiso.
Chilean authorities decreed red alert in Valparaiso and Vina del Mar for several forest fires. / AFP PHOTO / ATON CHILE / Raul ZAMORA / Chile OUT / RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT 'AFP PHOTO / ATON CHILE / Raï¿½l ZAMORA /HO ' - NO MARKETING - NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS
(Photo credit should read RAUL ZAMORA/AFP/Getty Images)
TOPSHOT - A boy walks towards a stranded boat in San Juan del Sur beach, following the passage of Tropical Storm Nate, in Rivas some 140km from Managua, Nicaragua, on October 6, 2017
Tropical Storm Nate gained strength as it headed toward popular Mexican beach resorts and ultimately the US Gulf coast after dumping heavy rains in Central America that left at least 22 people dead. / AFP PHOTO / INTI OCON (Photo credit should read INTI OCON/AFP/Getty Images)
TOPSHOT - An inmate firefighter monitors flames as a house burns in the Napa wine region in California on October 9, 2017, as multiple wind-driven fires continue to whip through the region. / AFP PHOTO / JOSH EDELSON (Photo credit should read JOSH EDELSON/AFP/Getty Images)
TOPSHOT - A man runs as a big wave hits the pier of the port of A Guarda, northwestern Spain, during a storm on February 2, 2017. / AFP / MIGUEL RIOPA (Photo credit should read MIGUEL RIOPA/AFP/Getty Images)
TOPSHOT - The Oroville Dam spillway releases 100,000 cubic feet of water per second down the main spillway in Oroville, California on February 13, 2017.
Almost 200,000 people were under evacuation orders in northern California Monday after a threat of catastrophic failure at the United States' tallest dam. Officials said the threat had subsided for the moment as water levels at the Oroville Dam, 75 miles (120 kilometers) north of Sacramento, have eased. But people were still being told to stay out of the area.
/ AFP / Josh Edelson (Photo credit should read JOSH EDELSON/AFP/Getty Images)
TOPSHOT - Indian villagers travel by boat through floodwaters in Balimukh Ashigarh village in Morigoan district, in India's northeastern state of Assam, on July 4, 2017.
Floods have affected 350,000 people living across 13 districts in Assam as the annual monsoon rains continue to cross the Indian sub-continent. / AFP PHOTO / Biju BORO (Photo credit should read BIJU BORO/AFP/Getty Images)
TOPSHOT - Aerial view of the extensive damage caused by mudslides as a result of heavy rains, in Mocoa, Putumayo department, Colombia on April 3, 2017.
Rescuers clawed through mud and timber Monday searching for survivors of a mudslide in southern Colombia that killed 262 people, including 43 children, and left relatives desperately seeking loved ones. / AFP PHOTO / LUIS ROBAYO (Photo credit should read LUIS ROBAYO/AFP/Getty Images)
TOPSHOT - Bystanders look on as floodwaters rage past a damaged building in an area of Freetown on August 14, 2017, after landslides struck the capital of the west African state of Sierra Leone.
At least 312 people were killed and more than 2,000 left homeless when heavy flooding hit Sierra Leone's capital of Freetown, leaving morgues overflowing and residents desperately searching for loved ones. An AFP journalist at the scene saw bodies being carried away and houses submerged in two areas of the city, where roads turned into churning rivers of mud and corpses were washed up on the streets.
/ AFP PHOTO / SAIDU BAH (Photo credit should read SAIDU BAH/AFP/Getty Images)
TOPSHOT - Experts inspect the cut-off section of the A20 motorway at the site of an unexplained landslide near Tribsees, northern Germany, on October 10, 2017.
The road to the west slumped about half a meter at the end of September on a length of about 100 meters. Currently, the motorway is completely blocked in the direction of Rostock, in the direction of Stettin is still a trail passable. / AFP PHOTO / dpa / Bernd Wï¿½stneck / Germany OUT (Photo credit should read BERND WUSTNECK/AFP/Getty Images)
TOPSHOT - A man helps evacuate a woman from a flooded street in Mandra, northwest of Athens, on November 16, 2017.
Greek Prime Minister Alexis Tsipras on November 15 declared a state of mourning after a freak overnight downpour with the force of a 'waterfall' flooded three towns near Athens, killing at least 15 people. / AFP PHOTO / DIMITRIS LAMBROPOULOS (Photo credit should read DIMITRIS LAMBROPOULOS/AFP/Getty Images)
TOPSHOT - Vehicles pass beside a wall of flames on the 101 highway as it reaches the coast during the Thomas wildfire near Ventura, California on December 6, 2017.
California motorists commuted past a blazing inferno Wednesday as wind-whipped wildfires raged across the Los Angeles region, with flames triggering the closure of a major freeway and mandatory evacuations in an area dotted with mansions. / AFP PHOTO / MARK RALSTON (Photo credit should read MARK RALSTON/AFP/Getty Images)
Discover More Like This
BACK TO SLIDE
Australia, New Zealand and the Red Cross have all pledged aid, though reaching the remote area has proven challenging.
"The rugged terrain and loss of communications in the area impacted means it is taking time to build a complete picture of the damage but we know that tens of thousands of people are reported as requiring humanitarian assistance," New Zealand Foreign Affairs Minister Winston Peters said in a statement on Monday. (Reporting by Tom Westbrook in Sydney and Charlotte Greenfield in Wellington Editing by Robin Pomeroy)