# Multi Stage Retrieval for Web Search During Crisis
## 3 Materials and Methods
### Additional Queries  
The dataset is supplemented with the set of queries \(Q\) that defines the basic information needed for a disaster-response stakeholder and is extracted from the FEMA ICS 209 forms. However, the queries in \(Q\) are general and lack strong relations with the event under analysis. So, we reformulate the queries by adding more context (e.g., \"Have railways closed\" becomes \"Are railways disrupted or closed because of Hurricane?\"). This task was delegated to a language model using the following prompt:  
_I need to refactor some queries in order to better capture the information by adding more context to them <LIST OF QUERIES>._  
Another challenge related to the queries was their inability to cover all aspects of the crisis event. To address this, we generated multiple candidate questions using a language model. We split the set of queries into different groups based on the event type, and we ended up with general and event-specific queries. Afterwards, for each group, we generated additional queries using the following prompt:  
Figure 4: Representation of document embeddings using UMAP grouped by topic by BERTopic before and after the topic filtering. Each color represents a different topic.  
\begin{table}
\begin{tabular}{l c c} \hline \hline
**Topic** & **Score (\%)** & **Selected** \\ \hline beirut explosion, beirut blast, beirut, beirut lebanon & 75.00 & ✓ \\ tonnes ammonium nitrate, tons ammonium nitrate & 67.34 & ✓ \\ cause explosion unknown, cause explosion unclear & 62.43 & ✓ \\ news updates, page latest updates, latest updates & 42.72 & ✗ \\ hope stay safe, hope okay safe, hope safe okay & 43.71 & ✗ \\ really scary, damn scary, terrifying scary & 44.64 & ✗ \\ \hline \hline \end{tabular}
\end{table}
Table 3: Example of topic selection for event 009. Topic describes the cluster with keywords obtained from KeyBERT.  
Can you analyze this list of queries and add at least 30 more that are related to the event <EVENT TYPE/GENERAL QUERIES> but are not present in the following list? <LIST OF QUERIES>  
Subsequently, we manually selected the most fitting queries for each group, which expanded the semantic coverage for a catastrophic event.  
In total, we incorporated 20 general queries addressing broad concerns common to crisis situations and 10 event-specific queries related to the characteristics of each particular event. We limit the number of generated queries to avoid dealing with an overwhelming number of them. The following are some examples of general queries (<EVENT> is replaced dynamically based on the event):  
* Are there any security risks or criminal activities occurring due to the <EVENT>?
* What medical services are available for affected individuals?
* Are ATMs and banks functioning after the <EVENT>? The following are some examples of event-specific queries:
* Tornado: \"Are there any reports of multiple tornadoes forming during the tornado?\"
* Wildfire: \"What weather conditions are affecting the wildfire's spread?\"
* Hurricane: \"How far inland is flooding occurring due to the hurricane?\"
* Flood: \"Are any dams at risk of overflowing or failure due to the flood?\"
* Storm: \"How long is the storm expected to last?\"
* Accident: \"Has the air quality been affected by the accident?\"