What hazards will remain in Southern California after the wildfires subside?

Fires are continuing to burn in Southern California, with further weather-related threats expected to increase as another Santa Ana wind event picks up this week.

While the end to the fire danger is not yet in sight, the hazards that will remain in its wake will be severe, especially due to the urban nature of many of the burn zones, experts told ABC News.

The fires burning in Los Angeles and Ventura Counties are occurring on the urban-wildland interface -- areas where wildland landscapes meet with urban dwellings, Costas Synolakis, a professor of civil engineering at the University of Southern California who has studied how urban fires exacerbate post-fire related hazards, told ABC News. The further away from wildland, the less chance of ignition, which is why heavy winds were able to spark house-to-house spread quickly.

But these wildfires are so severe that they have penetrated into more urban areas, Scott Stephens, professor of fire science at the University of California, Berkeley, told ABC News.

The fires will have unprecedented environmental impacts, Synolakis said.

Landslides will be of great concern once the fires subside

Once the fires are out, landslides from burn scars will be a big concern when rain returns to Southern California and could be an issue for years to come. Post-fire debris flows are particularly hazardous because they can occur with little warning, according to the U.S. Geological Survey.

Post-wildfire landslides can exert great loads on objects in their paths, strip vegetation, block drainage ways, damage structures and endanger human life, according to the USGS. Additionally, wildfires could destabilize pre-existing, deep-seated landslides over long periods. Flows generated over longer periods could be accompanied by root decay and loss of soil strength, according to the USGS.

Landslides already historically occur in California. But conditions are currently extreme enough to warrant concern for increased threat, Edith de Guzman, a water equity and adaptation policy cooperative extension specialist at the University of California, Los Angeles, told ABC News

The wildfires are incinerating the shrub cover, so when a rain event does occur, the precipitation hits a ground surface that could be bare minerals and unable to soak it up, Stephens said.

"You're going to get flows of soil, rock and debris," Stephens said.

In Los Angeles, debris basins designed to catch some of the materials sliding down the mountain to lessen the threat of landslide hazards have been built in Mount Wilson and near Eaton Canyon.

The landslide danger will be especially dangerous in the Pacific Palisades, the neighborhood nestled in the lower hills of the Santa Monica mountain range on the Westside of Los Angeles that was decimated by the Palisades fire, because there is no debris basin there, Synolakis said.

"Palisades is going to be an area that people need to be on the watchout for landslides because the valley walls are steep," Synolakis said.

The houses that did survive the wildfire in the Palisades could also be in great danger of a severe rainstorm undercutting the foundation, Synolakis added.

Homes near creeks and steep hills could also contribute a lot of debris to landslides, Stephens said.

An average of 25 to 50 people are killed by landslides each year in the U.S., according to the USGS.

Long-term pollution could impact the region, experts say

An even bigger concern than potential landslides is the environmental impact of the fires, Synolakis said. In the near future, these burned-out communities will be filled with cleanup crews dressed in hazmat suits, Hugh Safford, a research fire ecologist at the University of California, Davis, told ABC News.

Since the fires are burning down manmade structures, the materials used to construct homes and cars are depositing toxins into the air and ground as they combust, the experts said.

"This is going into the local creek systems and in the local soils," Safford said, adding that many of the homes built before the 1980s likely are filled with asbestos.

Debris from the scorched homes near Malibu's Big Rock will end up in the ocean as well -- by wind and sea -- due to the proximity to the coastline, Synolakis said.

In Altadena, homes that were destroyed near the San Gabriel Valley Groundwater Basin could contribute pollutants to the water system, De Guzman said.

Researchers are already monitoring soil to see what kinds of heavy metals and other toxins have seeped in during the combustion process. It won't be long before the toxins end up in the ocean through the watershed, Synolakis said.

The environmental impact of a series of wildfires this big is yet to be seen, Synolakis said. And the cleanup process will be long and arduous, Safford said.

Fire danger expected to persist

On Monday afternoon, winds will begin to pick up in the mountains and higher elevations gusting 20 to 30 mph, locally 50 mph.

There is very little rain relief for the fires in sight for the Los Angeles area in the near future, forecasts show.

While there is a 20% chance for a sprinkle on Saturday, that precipitation is expected to occur closer to San Diego.

Dry conditions are expected in the long term as well. Last week, the National Oceanic and Atmospheric Administration declared that La Nina conditions are expected to persist through April 2025, with Southern Californian expected to be very close to drier than normal.

But even low rainfall amounts could trigger dangerous flash flooding that can unfold very quickly, as recent wildfire burn scar areas are especially prone to flooding, mudslides and landslides. In some instances, burned soil can be as water repellant as pavement, according to the National Weather Service. The susceptibility to flash flood within the burned area is greatest during the first two years following the fire.

The general rule of thumb is that half an inch of rainfall in less than an hour is sufficient to cause flash flooding in a burn area.

Ideally, several light to moderate rainfall events in the region would be best to significantly diminish the current wildfire danger and gradually soak the ground.

ABC News' Daniel Amarante and Daniel Peck contributed to this report.