The volume of mortgage applications filed in the past week jumped more than 10% as turmoil in the Middle East sent interest rates lower, spurring more lending activity, the Mortgage Bankers Association said in its Weekly Mortgage Applications Survey Wednesday. A survey of loans applications for the week ending Feb. 18 shows the market composite index — a measure of loan volume — growing 13.2% on a seasonally adjusted basis when compared to a week ago. On an unadjusted basis, the index increased 14.8%. The four-week moving average for the seasonally adjusted market index is up 1.9%, while the four-week moving averages for the purchase index and the refinance index are up 1.6% and 1.8%, respectively. Refinancing activity increased to 65.7% of total applications last week, compared to 64% a week earlier. The average interest rate for a 30-year, fixed-rate mortgage fell to 5%, compared to 5.12% a week earlier. In addition, the average rate for a 15-year, fixed-rate mortgage declined to 4.28%, down from 4.34%. Write to Kerri Panchuk.